BBC Research & Development exists to give competitive advantage to the BBC through technology

BBC R&D ANNUAL REVIEW 1 BBC R&D exists to give competitive advantage to the BBC through into the production office. Our work to improve the coverage of new digital Days at Kingswood Warren in May technology. This year, we have played a leading part in some of the BBC’s integrates the networks, hardware, services; but there is now a real (if long 1999, at which all our major projects most significant achievements: a team effort between R&D people and software, metadata and middleware term) prospect of a switch-off of were on show, and which generated colleagues from all parts of the BBC and our partners in industry. needed to allow media files to be analogue services. Our spectrum planning many useful contacts and ideas for the transferred and manipulated easily and experts have made a key contribution future. We have continued our cheaply through the production process. to UK thinking on how to achieve this: programme of staff attachments Among our achievements were world the systems and technology developed technologies of digital broadcasting, This year our work on speech in the coming years this contribution between R&D and the other divisions of firsts in digital broadcasting, including and delivered by BBC R&D. R&D is able to devote more resources recognition has come to fruition. It is will become even more critical. the BBC. And our publications effort the first enhanced TV service on DTT, This year, we have been able to to supporting the needs of programme already in regular use to index the We are particularly proud that our has been re-doubled, with a particular the first public audio description service transfer more of this technology to the makers. This is highly complementary News archive and to increase the work has received recognition from our emphasis on creating material accessible and the design for the first single chip operational areas of the BBC. Our team to the BBC’s ‘Imagineering’ initiative amount of subtitling that we can do; colleagues in the industry. The National through the BBC Intranet – like this DVB-T demodulator. Our work on of IT specialists who designed and built which explores new kinds of programme and further applications are in Academy of Television Arts and annual report! programme-making led to the first the infrastructure for the BBC’s Online content; and it reflects the increasing development. Elsewhere, technology Sciences in the USA awarded us our As always, the achievements of the prototype digital radio camera, the first services have now transferred to Online importance which the BBC is placing on developed as part of our work on third Engineering Emmy, recognising year are the result of the outstanding demonstration of media objects moving Operations. Responsibility for the the business of producing programmes. digital television has led to a new digital ‘Sound in Syncs’, our pioneering work commitment, energy and creativity of between standard PCs across standard Digital Radio infrastructure is being Virtual Production therefore wireless camera. This provides a in digital distribution technology. R&D’s the staff at BBC R&D. Our team is IT networks; and the first depth- taken over by Radio and Resources; and remains one of our major themes. Its versatile and flexible tool for studio use special expertise in High Definition TV stronger than it has ever been; and our mapping system for the Virtual Studio. we have less involvement in the day to benefits are partly in simple cost as well as news and sport. helped the BBC win awards for effectiveness will be enhanced further The nature of these achievements day running of digital television services. savings. But it also allows us to create Developments in digital technology A Midsummer Night’s Dream and Cecilia by our continuing participation in the reflects the changing priorities in Of course there is still much to do to programmes that would never have are leading to exciting possibilities in & Bryn at Glyndebourne. And R&D’s multi-function teams of the BBC. our work. complete the digital broadcasting been possible with traditional the home. As more programmes and contribution was prominent in the For a number of years we have picture and we continue to devote a lot techniques. The concepts are now interactive services become available, teams which won Production Solutions been strongly focused on the of energy to this field. In particular we expanding to virtual actors, as well as and as more content is available Awards at IBC ’99: BBC Digital Services development of digital platforms for are breaking important new ground in sets: the potential is enormous. through the web or stored on hard were recognised for the launch of the broadcasting and online services. The the delivery of effective multimedia, A major new area of work is to disc, we will see the consumer BBC’s new digital television services; BBC was the first broadcaster in the data and text services, especially the bring IT technology to support the experience evolve away from reliance and the SMART project received an world to establish a complete set of schedule information needed by digital production process. Much of today’s on the conventional broadcast schedule. award for their work on multi-camera, digital services, offering television and Electronic Programme Guides, and in broadcast equipment is specialised and Our work on Navigation will help our cable-free programme acquisition. radio on terrestrial, satellite, and cable ancillary services like signing and audio expensive; but IT has now reached the customers find their way around this One of our biggest challenges is networks, with a complementary description which are of tremendous point where many of the production new world of content. how to share with our colleagues in the Online presence for people with access value for our disabled audience. functions can be carried out on a normal Alongside these areas of attention, other divisions of the BBC the to the world wide web. These services But as the BBC becomes desk top computer, bringing faster, we have continued our leading-edge knowledge and insights we gain from Peter Bury would not have been possible without increasingly familiar with the cheaper and more effective processes work on spectrum planning. We continue our work. We held a series of Open Head of Research & Development

2 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 3 Foreword 2 Awards 6

Studio matters 9 Digital broadcasting 35 Spectrum planning 57 Delivery to the home 67

ORBIT project 10 Technical architecture 36 Digital television 58 Home storage 68 Watermarking 14 Audio description for digital television 42 Digital radio 62 Digital radio Mondiale 70 Virtual production 16 Capacity planning 46 Analogue spectrum planning 64 New services, new radio 72 Virtual production audio 20 Digital text, enhanced TV and 48 Mobile television 76 Speech recognition in broadcasting 22 interactive platforms Licence protection 78 Pro-MPEG forum 24 Schedule interface 52 New chip 79 Multichannel sound 26 Widescreen television 54 High definition television 28 Radio cameras 30 New display devices 33

BBC R&D ANNUAL REVIEW 5 Once again, the quality of our work has been recognised by our peers. This year we have received many awards, covering many of the areas of our work.

PRODUCTION SOLUTIONS AWARDS 1999, PRESENTED AT IBC In September 1999, the BBC and its collaborative partners received several awards and commendations. BBC R&D was a significant contributor to several of these. BBC Digital Services received the award for the Launch of the Year for the launch of the BBC’s new Digital Services. BBC R&D was the design authority, providing technical input in the provision of the technical architecture. BBC R&D and the BBC’s SMART project won the award for acquisition technology for their work on multi-camera, cable-free programme acquisition. SMART have been pioneering the use of new technology to create low cost, high quality programmes. BBC R&D’s part in the award winning work was to provide guidance on cable-free cameras. The award for Transmission Technology was given to the MOTIVATE collaborative project for its work on mobile digital terrestrial television, and in particular for the demonstration of TV on a Tram at IBC ’99. The award reflects the NATIONAL ACADEMY OF work of all the partners in the MOTIVATE project, including BBC R&D, and TELEVISION ARTS especially Nozema, Deutsche Telekom and NDS. AND SCIENCES EMMY FOR In addition, we were highly commended for the Plasma Display Panel interface SOUND IN SYNCS (now licensed to Delphi), and highly commended under ‘Achievement in Acquisition’ Nearly 30 years after its completion, together with Playback HD for the making of Cecilia & Bryn at Glyndebourne. The the BBC’s sound distribution same collaboration won the Best Television Presentation of a stage dance at ‘Dance technology, Sound in Syncs, has won an Screen 99’ June 1999. Emmy – BBC R&D’s third. Sound in Syncs (SiS) – the digital transmission ...AND SOME AWARDS WON system used to convey television sound BY OUR INDUSTRIAL PARTNERS between studios and transmitters – We are keen to see our ideas successfully taken up by industry. This year, three such was in BBC service for more than products have received major awards. 15 years from 1970 and was adopted At NAB ’99, Snell & Wilcox won the IBE editors award for Steadyshot, now by many other broadcasters. It enabled called Shake Out, and Radamec won the Television Broadcasters’ Pick of the Show the sound and picture signals to be award for free-d. combined and was the first example of At IBC ‘99 the Peter Wayne award was presented to Snell & Wilcox for broadcast equipment, in quantity Archangel, a system which improves the quality of archive material. Both production, to make extensive use of the Snell & Wilcox products are derivatives of work developed with our help in the digital techniques. Aurora project.

6 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 7 ORBIT project watermarking virtual production virtual production audio speech recognition in broadcasting ProMPEG forum multichannel sound high definition television radio cameras new display devices

BBC R&D ANNUAL REVIEW 9 browse

essence

metadata

acquisition

Mole-equipped real-time playout

live material

The ORBIT project is a pilot to show how inexpensive IT equipment can replace many of the facilities currently requiring relatively expensive specialised production apparatus. archives We can make significant savings if we system, many production tasks can decisions are executed using standard use mass-market IT hardware to be readily effected via personal desk-top PC terminals. The technology replace specialised broadcasting computers on the office desktop and can be implemented more rapidly if the equipment. Bit-rate reduction would be the BBC’s media assets can be managed video is compressed – to reduce the necessary to make a practical more efficiently. bandwidth required on the network implementation, with the consequent The ORBIT pilot will demonstrate, and the storage required on the need to decode signals to on a small scale, an IT-based system servers. The challenge for ORBIT is to uncompressed form and recode again at for programme production, playout recommend and demonstrate the best various places in the broadcasting chain. and archiving. practices for a high quality, flexible The former BBC-led ACTS ATLANTIC implementation at a low cost. project provided the means of doing THE CONCEPT this without the progressive Orbit starts from the premise that BACKGROUND deterioration in quality normally nearly all of the various processes in a ORBIT is being planned to experienced with repeated decoding broadcast centre can be linked using an incorporate the requirements of and recoding. IT network. Of course, this is only television operational areas. For The BBC makes extensive use of IT possible if the material is in digital form. playout, material can be either equipment for business applications and Programme material is acquired and recorded or live. Recorded material is has extensive IT networks linking its stored on file servers which are stored in file servers and played to air premises. If television programme- connected to the production, playout via the presentation desk in the playout handling and office-based systems can and archive areas by way of IT area. Programmes for ‘live’ be linked to each other in a common networks. Many of the editorial transmission, from local studios or

10 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 11 outside broadcasts, will be passed via on-line access, and suitable for fast, interconnected. Any implementation of areas, ORBIT-based systems will be The Portuguese technical institute capture, production, playout and directly to the presentation desk. The slow and reverse replay (i.e. shuttling). such a system needs to be both built around a number of linked INESC (Instituto de Engenharia de archive areas. Each area is connected to material stored on the servers In a production area, where many re-configurable and scalable. Different networks. Gateways will provide inter- Sistemas e Computadores) is providing the others through gateways, which can comprises both video and audio editors may be browsing material, a configurations are needed to fulfil connections between these networks, valuable specialist expertise in our work act as firewalls if required, giving the programme material (known as large number of programme segments different business needs, and the and in most cases will act as ‘firewalls’ on middleware. necessary security. In the pilot, the essence) and metadata. Some of (‘clips’) and even complete programmes system has to be capable of expansion to protect sensitive areas. In order to make a practical programme intake handles material the metadata might be broadcast – for may need to be handled. In contrast to to fulfil future needs and technology The use of both ATM and Ethernet IT-based system capable of handling and intended for storage and later example as teletext. However, much of the traffic in playout, much of this shifts. The system needs to be able to is planned in order to gain an storing digital television signals, it is transmission. Live material is routed it will relate to the business side of material does not require real-time contract, too, and adapt appropriately understanding of their strengths and necessary to use a substantial degree of directly to playout. broadcasting and be kept confidential. transfer, nor is it regarded as to accommodate partial failures weaknesses. Ethernet is relatively bit-rate reduction. A full-quality video The production area could be used The use of metadata is expected particularly urgent. Some of the files may (e.g. the loss of one or more of the inexpensive, and is already implemented signal needs typically about 270 Mbit/s. by any of the programme making or to grow rapidly once the facilities be delivered overnight and temporarily servers) when these occur. on a large scale throughout the BBC. It Using video compression, the bit rate continuity groups in the BBC. become available and formats are stored locally to the workstations, so The IT devices will often be would seem to be very suitable for can be reduced to 10 to 20 Mbit/s In playout, pre-recorded material (hopefully) standardised. that browsing occupies less network clustered together in areas providing applications which do not depend upon whilst still preserving very good image is played from the servers via the In the future, ‘production offices’ capacity. Even so, the convenience may capture, production, archiving or the real-time exchange of signals. It is quality, adequate for the majority of network and desk to the transmission will be created in which a number of encourage the browsing of more playout facilities, but there will also be conventional wisdom to use ATM studio and post-production operations. coders at the output. Quality is editors work together on the same material by programme makers. This the need for connections over greater where a guaranteed quality of service Repeated coding and decoding between maintained through the decode-recode programme or series of programmes will increase the re-use of archives but distances, such as between regional is needed to ensure real-time exchange. 270 Mbit/s and the compressed signal process by using the Mole. Live using desktop terminals. They will have in turn will place heavier demands on centres. ORBIT will study the options ORBIT will explore the use of ATM could severely reduce quality. We material is fed directly to the desk. networked access to servers which hold the networks and servers. for managing the network traffic. to test whether it is beneficial in propose to use Mole technology to Live material includes News all the material captured in the studio, The production area needs to be In order to manage the large amount real operations. maintain quality throughout the programmes, which would comprise or acquired by conventional means. The able to read, contribute, add to or of traffic within and between areas, There will be extensive use of distribution chain. Mole technology both live and recorded material sent suggestion is that preliminary selection, modify the existing metadata if the full and to provide security for sensitive CORBA middleware, to facilitate the was developed in the former from a local News presentation area editing and final assembly of the efficiencies are to be achieved. interconnection of the various IT EC-funded ACTS ATLANTIC project, configured similarly to playout. material will be done using IT The archive forms an important part devices with each other. The and was recently standardised by the The archive will contain suitable technology and infrastructure. Some of of the pilot. The ability to browse middleware is effectively a common SMPTE. ‘Mole’ is a registered trade PC-hosted coders and decoders to the final processes may be carried out archive material easily, with more rapid ORBIT is an acronym for standardised layer of software which mark of one of the partners of the facilitate transfer of material to and in a separate edit area, to provide and convenient access than by using ‘Object Reconfigurable Broadcast looks after the network ATLANTIC consortium. from tape in the DVTR-based archive. better listening and viewing conditions. distribution on VHS tape (which is Infrastructure Trial’ inter-connections and scalability, but ATLANTIC also provided the The main objective of the ORBIT Edit decision lists from the production currently the normal method of hides them from the users so that their technology for transcoding video signals pilot project is to provide advice on office will be exported to the edit area delivery), and supported by full ACTS is an acronym for perception of the system is simplified. at the best possible quality from studio best technical practices. We aim to gain for refinement and conforming of the edits. metadata facilities, will encourage ‘Advanced Communications All of the devices connected into the bit rates to the lower bit rates required experience of different network Many of the cost and efficiency producers to make better use of the Technologies and Services’ system are capable of communicating for distribution. implementations, and to develop savings are obtained because the initial material in the archives. with other workstations, file servers middleware to be able to realise a searching of material can be carried out ATLANTIC is an acronym for and processing equipment through this THE ORBIT PILOT reconfigurable system. using existing, inexpensive office IT THE PROPOSED ‘Advanced Television at Low middleware. Each manufacturer has to The ORBIT pilot will select suitable facilities. High compression will IMPLEMENTATION bit rates And Networked provide a single interface to the technology and implement it in a enhance this efficiency. A reduced- For the full benefit of an IT-based Transmission via Integrated network using middleware rather than a demonstrator. Another objective is to quality version of the programme will system to be realised in an operation Communication systems’ host of different interfaces to each of prove the viability of an open standard be produced specifically for browsing the size of the BBC’s, a very large the separate systems in turn. for middleware. The initial proposal is number of IT devices need to be to divide the broadcast chain into

12 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 13 WHERE DID THAT Similarly, broadcast watermarks are for example, which help keep track of will probably result in an unfavourable picture before we add it to a scene, wide-ranging surveys of material in the PROGRAMME additional signals that we add to the all the associated business knowledge. It public response. but these are the very actions which market to identify unauthorised COME FROM? programme material. Under normal is not necessary to embed the In practice, we want to recover the defeat some watermarks. Similarly, broadcasting or copying. Digital technology makes it easy for us conditions these are not visible or knowledge, just a key which links to the information in the watermark. If this is there are audio processing techniques The BBC is now considering how to record and re-use material. The audible, but with careful processing we appropriate business systems. hidden behind the programme, it may which can upset audio watermarks. best to proceed. Part of the problem is quality is good and does not degrade in can recover the embedded signal. Metadata will play a vital part in be very difficult to recover. The human For a watermark technology to have that there is not a single solution to all the same way that the old analogue Ideally we can use watermarks to this process. eye and ear are very sensitive a long life, we need to make it difficult our needs. How to cope with the formats did. As a consequence it is easy convey data – the rights owner, the instruments. It is difficult to create a to attack. myriad of partial solutions has not yet to lose track of the rights owner. This date and time of capture or broadcast, WHAT ARE THE watermark which the eye and ear do If we want to make a watermark been decided. may be an accidental process during and a range of other useful information. CHALLENGES AND not notice, but which can be detected more rugged, there is a compromise to This is not a problem unique to the production, or a deliberate act by a TECHNICAL by a machine. In practice this appears be made. Rugged watermarks are BBC. The EBU has also been car-boot salesman or an unscrupulous HOW COULD WE CONSTRAINTS? to limit the amount of information that usually more noticeable on the considering watermarking. In this arena, broadcaster. We need some help to USE WATERMARKS IN When we add a watermark, either to a we can embed in the signal. programme. No-one has yet produced there is an interesting ability for identify who owns the rights. OUR BUSINESS? picture or a sound track, it is really an Many of the early commercial an ideal solution of a watermark which manufacturers and suppliers to meet Now there are many people The most immediate interest we impairment to the original programme. watermark systems were designed to is both rugged and invisible/inaudible. and influence broadcasters. offering systems which will track images have is to protect our broadcasts from Some systems deliberately make the prevent still photographs being copied and sound. These products rely on the unscrupulous copiers. There is a large watermark noticeable. For example, without the owner’s permission. As THE WAY FORWARD SECRECY technology of watermarks, supported potential market for bootleg copies of this is often the case for still pictures with all forms of scrambling, There are several organisations offering Once the existence of a watermark has by business systems to follow their trail. our programmes, but by adding a which are advertised publicly using a encryption, etc., some people tried to proprietary watermarking systems, and been made public, the academic watermark, we can demonstrate the watermark, which is removed when overcome the protection for fun (often we have been experimenting with the community takes a delight in cracking WHAT ARE WATERMARKS? source and use the evidence in customers pay the appropriate fee. students of mathematics fall into this technology in the BBC. This has helped the system. One way of avoiding this is We all know how a watermark works in legal proceedings. For the BBC’s main broadcast material, category), whilst others tried to us to understand the strengths of the to keep quiet about the existence of paper. Normally the watermark is not The more subtle use is to track noticeable watermarks are not overcome the protection for illicit gain. different commercial systems – we are watermarks and their standards. visible, but if we look at the paper material as it progresses along the desirable. Anything which degrades Unfortunately, some of the most talking to all the major manufacturers There is no doubt that we will be under certain lighting conditions, we broadcast chain from capture, through the quality of our pictures and sound successful forms of attack are used in in the field. using watermarks in future, but the can see an outline embedded into the production and then to play out. We will make difficulties in production, bona-fide production offices as an The fundamental watermarking issues of who knows what will need paper itself. can consider methods of identification increase the bandwidth required artistic tool. We often resize, rotate, technology is often linked with business careful managing. of material, embedded into the picture when we broadcast the signals, and stretch or otherwise manipulate a management services. These may offer

14 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 15 Virtual production is a relatively new television technique in which all or part of the scenery is inserted into the image electronically, rather than being physically present. This can save time and money, by eliminating the need to build, transport, rig, break down and store physical sets. Virtual studios also provide new artistic freedom, since we can create backgrounds that are physically impossible to build in a real studio. However, virtual studio techniques must fit in well with current studio practices, and must not place significant limitations on what is possible. They must also be capable of producing a high degree of realism. We are promoting the use of the current virtual production technologies into real operation, and are investigating the use of virtual studios to originate content for new media such as 3D, interactive or immersive television and video games.

16 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 17 Free-d camera tracking system Truematte virtual production techniques. These improved by deriving a better law to This can be used to generate animated 3D scenes produced using In virtual production, it is vital that we Conventional chroma-key techniques programmes were produced with the relate the degree of defocus to the automatically the mask signals required virtual production techniques. know the precise position of the require the use of a brightly-lit aim of testing the limits of what was distance of virtual objects, giving a to allow actors to walk around a virtual Another application is the provision camera to ensure that the virtual background of a uniform colour, usually possible with the technology. Both more natural defocusing effect. object, as well as to allow the simple of additional multimedia material in background image is correctly inserted. blue. It can be a time-consuming task programmes were produced We expected that there might be representation of actors as animated association with a digital broadcast. We have developed a system that to light such a background, and difficult successfully, but were not problems combining Truematte with a 3D objects in a 3D world. The actor This is a key aspect of the SAMBITS measures the position and orientation or impossible to use subtle lighting without problems. standard teleprompt machine, but the tracking system is based on the project which is studying the use of of each camera using markers placed in effects on the actors. Our solution to One problem was achieving good Tomorrow’s World experience showed hardware developed for free-d, and MPEG-7 to allow users to select the the studio ceiling. A small auxiliary this is a method using a retro-reflective registration between real and virtual set that there were none. works by analysing the silhouettes of content they wish to view. Unlike camera mounted on the main camera cyclorama cloth and a ring of coloured elements. This was found to be due actors against a Truematte floor. MPEG-4, MPEG-7 is a standard being and a processing unit to analyse the lights around the camera lens. This largely to a combination of inexperience developed to describe content, rather image allows us to compute the camera ensures that the background always of the production staff in the use of THE NEXT GENERATION OF MPEG-4 and -7 than encode it, providing metadata position from the known marker appears brightly-lit to the camera, virtual set technology, and the effects of VIRTUAL PRODUCTION MPEG-4 is the next generation of digital that allows viewers to select content positions. The system is licenced to regardless of the setting of the studio lens distortion when the camera lens video (and audio) compression. It according to descriptions such as Radamec Broadcast Systems who lights, which can instead be set for the was set to a wide angle. A set of PROMETHEUS extends the coding capabilities of programme genres. One example of market it under the name free-dTM. desired dramatic effect. guidelines were prepared to help staff This year has seen the start of the MPEG-2 by allowing a scene to be the kind of service that SAMBITS achieve better alignment, and we have PROMETHEUS collaborative project, composed of several individually-coded could support is the provision of 2D Digital video effects Introduction of the now started on the development of a which will demonstrate an end-to-end objects, rather than coding the image as sign language. MPEG-4 may also If the camera is restricted to pan, tilt technology into studios unit to correct lens distortion. 3D programme chain, using virtual a single entity. The visual coding tools find application in the provision of and zoom, with no lateral movements, Virtual production techniques change Several improvements have been studio techniques and incorporating provided include tools designed low bit rate video, both for delivery then there is no need to use an both the technology and the business made to the items of virtual production high-quality virtual actors. The scene especially for moving video (similar to via the internet and as a ‘browse’ expensive graphics computer to render practices. We are promoting the equipment so far produced. The ‘2D will be encoded as a collection of 3D MPEG-2), still pictures, text, 2D and format for viewing video on PCs a new view of the 3D world every changes. There are technology gaps DVE’, which creates virtual models using the new MPEG-4 coding 3D graphics, as well as animated human over an intranet. frame. The virtual background can be which have so far prevented virtual backgrounds from video signals, has standard, and the decoded scene will be face and body models. MPEG-4 represented as a flat image which is studios from reaching their full been modified to give better displayed on a 3D display. The provides audio coding tools specially transformed to simulate the effects of potential. We have created solutions to registration between real and virtual set technology being developed will be of adapted for speech, music, text-to- camera panning, tilting and zooming. improve the performance and elements. This was achieved by use both in ‘conventional’ virtual speech, synthetic (or structured) audio We have developed a specialised DVE credibility of the technique. We have improving the law that relates variations production, as well as demonstrating and acoustic rendering. MPEG-4 is now for performing such transformations, on been working with real productions to in lens angle to the setting of the what might be possible for new kinds of an International Standard, with further either a still or a moving image. The help gain better understanding and to camera focus. The device for simulating media, including interactive TV and 3D TV. enhancements due to be added shortly. system is licenced to Radamec aid the transfer of the technology. For depth-of-field effects has been Within the project, we have already We are examining the potential for Broadcast Systems who market it under example, we worked with Tomorrow’s developed a system for tracking the using MPEG-4 in several applications. the name Virtual Scenario. World to make two programmes using positions of actors in a virtual studio. One application is the encoding of

18 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 19 main input dsp 1

surround left dsp 3 early sound processor left direct sound

panner centre 6 early reflections right dsp 2

2 object signals surround right

reverb. processor ambience/ effects input 4 reverberation signals

Arrangement of dsp modules.

In television production, the use of synthetically-generated visual self-evident. For the purposes of the REVERBERANT SOUND (due to interference patterns) but do so images is becoming well established. So far, most of the work has been experimental system, the space is The reverberation processor is based smoothly. In the case of the model, the carried out on the video picture generation, but it is also important to assumed to be a ‘rectangular’ room. on well-established principles employed basic control sampling interval of 20 ms create a credible audio illusion. It is well known, from common That gives six first-order surface by commercial artificial reverberation would give rise to step phase reflections and makes the calculation of generators. The overall properties of discontinuities, corresponding to every observation of almost any badly dubbed television programme or the discrete image locations trivial. No the space are calculated from basic 7 mm of movement. It is necessary to cinema film, that discrepancies between the audio and visual spatial second-order early reflections are acoustic principles. The reverberation is interpolate the sampling interval to give cues significantly degrade the illusion of reality. included. The ideal (3-D) model is assumed to be controlled by boundary a finer resolution. modified to fit the 2-D reproduction surface absorption, uniformly THE HUMAN HEARING reflected, absorbed or diffracted by THE EXPERIMENTAL paradigm by mapping the reflections distributed on all surfaces, together NETWORK INTERFACE SYSTEM AND SYNTHETIC the object. It is impractical to create AUDIO SYSTEM from the walls, floor and ceiling onto with air absorption. The required The audio virtual production system SOUND FIELDS even a reasonably accurate model of The experimental system consists of a the horizontal plane. The room reverberation time is an input control will eventually be controlled from the The human hearing system is well anything but the most primitive commercial digital signal processing geometry, source and listener locations parameter. The reverberation video system, by way of a source adapted to obtaining spatial cues from acoustic space. It may well be (dsp) development platform, and uses are input control parameters. All of processor also has a second input port tracking system. A TCP/IP network the acoustic environment. Evolution unnecessary anyway. For the creation three, 40 MHz DSP56000 processors in the seven discrete sound source for ambience and effects. interface and management system is has ensured that maximum use is made of a credible sound impression in a an industrial, IBM-PC® type computer. images are mapped onto the included in the audio virtual production of sound parameters and clues relating virtual production, a relatively simple The audio image processing is divided reproduction loudspeaker layout by INTERNAL OBJECTS processor, to form a communication to relatively close sources, up to a synthesis will result in a convincing between the processors. One amplitude panning. The basic acoustic model represents channel for control packets. time delay of about 30 ms. After audio illusion, partly because it is produces the direct and six delayed The direct sound and the early only the interior surfaces of the empty that time, the sound is blended and assisted by the visual information. early signals and the second produces reflections are potentially subject to room. One internal object is included in MANUAL heard as reverberation. At its simplest, the sound field the four reverberation signals. The several different kinds of frequency the model, either as an obstruction or CONTROL SYSTEM Sound, starting from a source, reaching a listener can be divided third combines these signals to filtering, for example the selective as a reflector. The two additional signals For the purposes of testing and travels outwards in all directions at into three main components, the produce the panned output signals effects of air absorption over larger required for this are generated by the demonstration, a manual interface is about 340 m/s. That uniform spreading direct sound, a small number of to drive the loudspeakers. distances or non-uniform source direct/early DSP processor. included to allow input of room, source proceeds for only a short time, until discrete early reflections and the directivity. Those filter functions are and receiver geometry and acoustic part of the sound wave strikes some overall reverberation. DIRECT AND EARLY SOUND approximated by simple filters. MOVEMENT room characteristics. A simple graphical object. What then happens is always Geometric modelling of the direct and When a source moves in a real room, interface allows the source and receiver complicated. The sound may be early sound is essentially trivial and large and rapid changes in level occur to be moved by the mouse cursor.

20 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 21 Speech recognition is advancing rapidly with several products for office dictation already available at relatively low cost. If we could apply speech recognition to the content of a programme then this would open many new ways of working with audio and video material. Unfortunately, the current speech recognition products are not suitable for this as they only work after training to an individual voice. However, by working with research groups who are developing more advanced, speaker independent systems we have been able to demonstrate some THISL PROJECT and a half years of BBC TV and radio each day, adding, on average, 35 hours applications in broadcasting. Indexing by using news output and allows this content to to the archive each week. speech recognition be searched in much the same way as a Applying speech recognition to dialogue It is not intended that this approach These two editing techniques could With a growing archive of recordings, it search engine can be used on the SUBTITLING editing can turn the task of audio should offer full facilities for editing be fully integrated into one editor to can be difficult to retrieve a particular internet. However, as well as viewing We are continuing to explore how editing into text editing for which a audio, as changes of intonation and allow working interchangeably either item unless it has been properly the text of the retrieved stories, THISL speech recognition can be used to help word processor can be used. With this other variations in delivery will, at with the audio (and video) or, instead, indexed, and this may not be practical allows the user to replay the produce subtitles. We have developed approach, the basic steps in editing are: times, mean that edits need to be with the text. The user could switch in many situations. Speech recognition corresponding audio clips to see if the an experimental system to evaluate our • Pass the dialogue recording auditioned and trimmed with more between these presentations at any time, could instead be used to produce text story is relevant to their enquiry. ideas and, with strong support from through a speech recogniser. sophisticated equipment. However, to use whichever was more convenient. from the dialogue in the programme Discussions and demonstrations of Subtitling Unit, are discussing the most • Edit the resulting text file with a simple audio editing features could be Editing dialogue in this way offers soundtrack and this could be used to the system have indicated that this appropriate way to make this available word processor, by highlighting included to allow edits to be trimmed these advantages: build an index based on the spoken approach offers much potential in as a commercial system. Following on text and using cut, paste and whilst auditioning. • Navigation around a recording content. Users could search this index providing an automatic indexing and from this work, we are looking at ways delete commands, etc., to When editing has been completed in can be quicker using the text. for words or phrases and then retrieve browse facility for broadcast output. of streamlining the process of change and audition the material. this way, the system can produce an • Word searching can be used on the corresponding recordings. Although manual indexing will provide a re-versioning imported subtitles for • Simultaneously edit the under- edit decision list (EDL) which can be the recorded dialogue. The THISL project, which ended in better quality of indexing data, as broadcast in the UK. There are several lying audio in the same way. used in a desktop editing system. This • Cut and paste can quickly discard January 2000, was a three-year THISL is entirely automatic it could steps in this process which we can This approach offers a quick way of permits the user to continue editing or re-order sections of material. EC-funded project which investigated capture a wider range of output than is automate although the more complex assembling material into the required from that stage but using more • A transcript of the evolving the use of speech recognition to index feasible at present. The results have stages will require speech recognition order as it is generally quicker to extensive editing facilities programme is available at any time. broadcast programmes. The been very encouraging, and we are to help convert the subtitles in an work with text rather than the audio where necessary. • Timings are produced demonstration system which we set up continuing to record more programmes optimum way. recording itself. throughout the programme. over the last year includes roughly two

22 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 23 THE PRO-MPEG FORUM high compression efficiency. It offers also involves a surrounding layer of MPEG-2 provides the compression flexible operating modes designed standards governing areas such as tools for digital television and sound, as specifically for the professional program-associated metadata, file and well as a framework for the reliable environment and enables a consistent data formats (‘wrappers’), network transmission of the resulting data. standard to be used throughout the interfaces, and system control. MPEG-2 is the universal choice for production and broadcast chain. Public interoperability trials and THE WORK OF THE FORUM This is an excellent educational audio and associated metadata files. A digital television distribution and The Professional MPEG Forum demonstrations at major trade shows The Forum aims to help educate opportunity for all participants. common file interchange format is an emission. It is also used widely for (Pro-MPEG Forum) was established in have helped to focus the work of the the industry in the use of MPEG-2 New technical work of the Forum essential building block necessary to contribution links, where bandwidth July 1988, under the leadership of Forum. Our first trial/demonstration and associated standards by the will include: realise the technical and economic is limited. Nick Wells of BBC R&D as the was at NAB in April 1999, with a following means: • Further specification of benefits of MPEG-based production Within the studio, MPEG offers chairman. It is an open association of second, smaller demonstration at the • Production of material operating ranges for MPEG in and distribution. Also, work is starting many advantages. For example, MPEG over 70 manufacturers and end users, 1999 Montreux TV Symposium. A third explaining the new the professional environment. on reaching consensus on the use helps us to use servers and working together to ensure demonstration took place at the digital standards. • File formats and wrappers for of standard network interfaces and inter-connecting networks to access multi-vendor interoperability of International Broadcasting Convention • Demonstration of MPEG file interchange. control protocols. original and archived material easily MPEG-2 broadcast equipment. This (IBC) in September 1999. The NAB interoperability. • Network interfaces and As operating ranges and interfaces and cost-effectively. Production and interoperability will ensure a free and interoperability trial involved over 150 • Organisation of tutorials protocols for file interchange. are agreed upon, it will be possible to editing becomes more efficient as we open market for broadcast products. pieces of equipment from 22 and seminars. • MPEG interoperability over define tests used to confirm use server-based architectures (which The Professional MPEG Forum is participating companies – a truly • Guest speakers at wide area ATM networks. interoperability at different parts of the are cheaper than specialised broadcast not a standards making organisation. significant and unique achievement. Forum meetings. • Specific focus on audio issues. system. The Specification and Test equipment) and playout becomes However, liaison with the formal The Pro-MPEG forum is an open For end users, participation in the Technical quality can be maintained in Group (with the help of test equipment more automated and cost-effective. standards organisations (MPEG, SMPTE, international association of MPEG Forum is educational in its own an optimum way by the consistent use manufacturers) will establish tests and Many manufacturers now offer EBU, etc.) is one of the key functions. equipment manufacturers, right. Not only will they be of MPEG-2 throughout the production encourage the development of suitable professional MPEG-2-based The Forum provides a bridge between component suppliers, and end users able to provide input to the debate and broadcast chain and through the test equipment. equipment for all stages of the new standards and practical, (broadcasters, program makers, facility on future requirements and intelligent use of transcoding between For a newly formed organisation of programme chain, including acquisition, interoperable product implementations. houses, etc.) dedicated to the architectures, but they will also have different MPEG-2 bit rates and diverse broadcast industry production, and distribution. Interoperability does not just involve a interoperability of MPEG-2 systems the opportunity to debate with structures. The File Interchange work professionals, the Pro-MPEG Forum has MPEG-2 is so popular because it is consistent approach being taken for the in professional broadcasting. manufacturers about their plans for will result in a common standard for the already made a big impact in improving an international, open standard, giving compressed video and audio signals. It future products and digital functionality. interchange of the compressed video, multi-vendor interoperability.

24 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 25 MEDUSA multichannel reproduction together ADAPTING THE FORMAT CONVERSION been gained into the ways in which channels that are desirable in the High Street retailers are selling an with less complex modes of SYSTEM TO THE ROOM Often material is created in one format experts structure their descriptions, five-channel mix should be considered increasing number of Home Cinema reproduction, such as stereo and mono. A system which works well in a test and needs to be converted to another. and these results are now being applied ‘extra’ elements and not mixed-down systems. As well as a large display, Medusa also considered the ways in chamber may not produce anything like The experience in Medusa is that to assessment of spatial sound fields, into a two-channel stereo version. these systems usually come with a which a mono or stereo signal, could be the same results in a normal home. this is no simple task. both on a macroscopic and a During the normal (stereo) multichannel surround sound system. made to simulate, or feed, a Medusa has been looking at different For upconversion to surround microscopic scale. production of two BBC programme These surround sound systems fit multichannel reproduction system. methods of equalisation to improve the sound from stereo, the majority of items, multitrack recordings were made well with content provided on DVD or These involved linked studies of perceived reproduction of multichannel expert subjects preferred unprocessed PROGRAMME PRODUCTION of the output of each microphone with similar recording material, where programme production and perceptual audio at home. This involved the study two channel material to the equivalent Medusa sought to clarify what needs to a view to attempting a later surround multitrack sound can be offered without elements, leading to a single optimised of means to compensate the non-ideal up-converted five-channel version, be done in order to create successful sound mix of parts of the programmes. compromise. However, conventional approach for domestic reproduction. configuration of a multichannel possibly because the algorithms multichannel recordings and how the It was found that whilst recording an broadcasters are at a disadvantage reproduction system in terms of reduced the quality of the front image techniques required could be opera, the normal practice of using a because the majority of our productions USE OF SUBWOOFERS TO frequency and phase response whilst increasing the impression of space. conveniently incorporated into existing spaced array of microphones placed at are created with a stereo sound track. MAKE SURROUND SOUND anomalies. The room acoustic For downconversion there was little recording methods, producing the front of the stage led to We have been seeking ways to record MORE PRACTICAL characteristics, asymmetry, and listener or no consistency across a range of consistently good results for both unacceptable variations in the sound material which may be required to be Any surround sound system requires a position, were also candidates for programme and recording types. multichannel and stereo reproduction. quality of a singer’s voice when it was reproduced in mono, stereo or a large number of loudspeakers. A correction. Part of the problem that we Some of the key findings were: panned between the front three multichannel environment. typical proposal might be for five had to face was that there is little SPATIAL ATTRIBUTES • Multiple microphone recordings loudspeakers of a multichannel When we are considering loudspeakers – the conventional two correlation between the perceived As well as good sound quality, we need are ideal for simultaneous or reproduction system. This effect was multichannel sound systems, there is for stereo, one in centre stage to give quality and the measured quality of a to ensure that the positioning of the subsequent multichannel rather more noticeable than when often a difference between an ideal better presence and two for the normal room. sound image is accurate and reliable. As surround mixdown. Extra normal two-channel stereo was used. In arrangement, and the typical ambient sounds in the rear. If these Loudspeakers do change this is a subjective effect (there is no microphones are required to the more sporting setting of a tennis arrangement that might be found at speakers have to cope with the full characteristics when they are placed way of objectively measuring the provide good perspective on match, panning proved rather more home. People tend to arrange the range of sound they can be quite big. close to walls or the floor (something perceived image of a sound source) we audience applause. successful, particularly since it was furniture to suit normal living, rather The ear cannot easily locate the which happens quite naturally when have to rely on human judgement to • Three-frontal microphone found that the normal microphone than to optimise the reproduced sound source of low frequency signals. So one they are used in practice). One of the quantify the differences in localisation. techniques that are appropriate placements and sound balances made field. We need to understand how our option is to use a single large loudspeaker partners in the project has developed a The project explored methodologies for accurate localisation tend to for two-channel stereo were quite material is really used when creating for all the low frequencies, and several system which could adjust the sound in from related fields such as psychometrics, be impractical in use because satisfactory for Dolby Pro-Logic programmes. What are the practical smaller ones for all the critical sounds such a way that the perceived timbre sensometrics, food and beverage they pick up too much decoding without any further constraints of listening in the normal which create the 2D image. This system was practically unaffected by the choice assessment and expert systems. This information from the back of processing or adjustments. domestic environment? is often called 5.1 surround sound. of room and/or position. It is a fully work is in a stage of relative infancy at the recording space. Medusa is a collaborative project Of course, there is potential for an automated system that adapts to the the present time, requiring many years Multichannel sound reproduction which was set up to examine domestic imbalance in sound quality if disparate actual choice of room and/or position. of study before conclusive results can accommodates a much greater level of multichannel systems, with and without loudspeakers are used, so Medusa has be shown (especially, we believe in the reverberation than two-channel stereo pictures, and to optimise them, developed specifications for a subwoofer case of beverage assessment). reproduction. Additional distant combining the requirements of to be used in a 5.1 reproduction system. Nevertheless, some valuable insight has microphones or digital reverberation

26 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 27 Twenty years after NHK defined ambitious targets, we are now seeing in front-of-lens as well as the costs Early in 1998 some drama tests shot in Paris and in the gardens around HDTV starting to take off. of technology. were recorded in the new American Hatchlands in Surrey. There is now, however, an HD standard. The settings of the More recently, programmes have Broadcasters in the USA have CBS, NBC and other US evolutionary approach to HD. A wide camera were devised between Sony, been produced and post-produced introduced digital services carrying broadcasters have arranged sponsorship range of lenses, image sensors, different BBC R&D and PMS of BBC Resources. using the new American standard HD HDTV although now, one year after the deals to cover the extra costs of degrees of digital compression and Two brief dramas were recorded; a equipment supported by facilities on launch, there is only a handful of broadcasting sport and films in the new different data rates allow appropriate specially written drama Family Man and loan from several of our suppliers. receivers. Australia has also announced formats. Discovery Channel, National capture and manipulation of images. In a brief Eastenders shot on the Within the BBC, the majority of the the decision to start digital services Geographic and other broadcasters this way the technical standards applied Eastenders set. Both dramas knowledge necessary for High delivering HDTV. Japan has announced have announced quotas for the within programme production can be demonstrated good results in a very Definition production resides with that digital HDTV services will numbers of high definition programmes selected to suit the technical and wide range of lighting conditions and engineers and managers at BBC R&D. commence within the next year. to be commissioned in 2000: in one commercial contexts of the backlighting effects. Recently the BBC’s SMART Venture A small, but significant, number of case a figure of 100 hours HD has been programme. Upconversion and the use The resolution and overall have become involved in the project productions are being commissioned in quoted. The price increment for HD of Super 16 film as well as the 720-line presentation of detail with the new HD about Concorde. They were able to high definition by American and programmes is being established as and 1080 line HD formats all have their equipment was found to be significantly observe details of the operation, Japanese broadcasters. 10–15%. place in the modern approach to better than with a conventional camera compare them to conventional Equipment to produce these improved picture quality. although it falls short of that achieved productions and identify the key programmes is becoming available in NEW THINKING ON HD with studio HD cameras. This is differences in effort and cost. significant quantities at realistic prices: Overall, the move toward high HD IN THE BBC through limited performance of the This will help the BBC to gain a for example, the new Sony HD definition production and post- Notable BBC collaborative productions CCDs and the use of a high level of coherent understanding of how the camcorder records a good standard production seems to be established using the old Japanese HD standard digital compression. market is developing and provide of HD and is not significantly different with financial support so as to attract included The Ginger Tree and a number Several recent HD productions enough data to judge our HD related in price or physical appearance from its use for higher value programmes. of concerts. Productions using the old using the obsolete European standard activities properly. the well-known Digibeta standard. Film But it is realised that the very European HD standard include Mahler’s have included segments shot using the post-production facilities in the US highest quality programmes can 8th symphony, the opera Ariadante, the new HD equipment. A Chopin have been equipping themselves for become unaffordable through high costs ballet A Midsummer Night’s Dream and programme included several sequences high definition. Cecilia & Bryn at Glyndebourne.

28 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 29 Cable-free cameras have been used for years in sports, news and outside broadcasts. Unfortunately, with analogue transmission the pictures often break up without warning. Now, with new digital technology, we can offer a reliable link. Producers and directors have the opportunity to use cable-free cameras in a wider variety of productions, indoors in studios as well as outdoors. The new digital technology gives freedom and flexibility – enabling the camera to go to places that were impossible before.

WORLD FIRST AT NAB movement for the camera operator to Our demonstrations at NAB 2000 in obtain interesting shots or to follow fast las Vegas were ‘world first’. We action. Radio cameras are commonly transmitted digital signals at about used at location broadcasts, particularly 20 mW in the 2.5 GHz band, using sports events. Now with the new digital an omni-directional antenna mounted technology, directors can use these on the camera. cameras for indoor productions too. The compact MPEG-2 video coder, mounted on the camera, provided a Production benefits high quality video signal sufficiently • Complete freedom compressed for reliable transmission. of movement. The ideal compromise between • Flexibility in use. compression and error correction is • Minimises need for still the subject of trials. extra cameras. • Improvement in safety – BENEFITS no trailing cables. Cable-free cameras, or radio cameras, • Eases set design. provide complete freedom of • Reduced set up time.

30 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 31 THE NEW TECHNOLOGY Compact COFDM modulator HISTORY The underlying technology for the • FPGA-based design. Of course, we already have digital cable-free camera is DVB-T. This • BBC/LSI Logic 64780 for analogue radio cameras – so why is uses COFDM – the proven system used FFT function. digital so important? for digital terrestrial TV in Europe. It is • DVB-T compliant 16 QAM Cable-free cameras, or radio cameras, rugged and provides special immunity 1/2-rate coding on whether analogue or digital, provide to echoes – the main problem for 2000 carriers. complete freedom of movement for the cable-free cameras. • DVB-ASI input from camera operator to obtain interesting Recent advances in Large Scale video coder. shots or to follow fast action. Integration have made a portable • MPEG, DV and other Analogue radio cameras are PLASMA PANELS demonstration of displays, ranging from package, but this is not the case yet in transmitter feasible. This is small coders supported. commonly used at outside broadcasts, In the digital revolution, the one thing the now ‘standard’ 42 inch, 480 line Europe. It may be that we see enough and light enough to be carried • 9 MHz/centred ‘low-IF’ particularly sports events, but there is that has remained relatively unchanged models, to a new experimental 60 inch competition from DVDs as the first high in a back pack on the camera. COFDM output. the problem that the picture sometimes in the home is the old cathode ray tube. HDTV model from Panasonic definition delivery mechanism. We use MPEG-2 video compression • Less than 6 W consumption. breaks up due to poor radio frequency It offers good quality pictures, and is (unfortunately there were only two Despite the intrinsic quality of to minimise the amount of data that transmission conditions. The problem is now very cheap considering the high in the world – which prevented most plasma panels, not all panels work to needs to be transmitted, and to Compact microwave transmitter that the signal bounces off walls, levels of technology that have been of the delegates from placing an their full capability. In the early days, maximise the ruggedness of the system. • 20 mW at 2.46 GHz. vehicles, trees and people, and distorts used to engineer it. order immediately). many systems used an analogue • Camera-back mounting. the received signal. This leads to break For many years we have seen These displays will make more connection for the video, often PAL • Simple omni-direction antenna. up of the signal and colour flutter, and other display devices competing for demands on the production and coded, using non-professional coders • Compact low-phase this has hindered the wider acceptance a place in the home market. Most of technical quality of the programmes built into digital set-top boxes. Our noise oscillator. of radio cameras in general programme them are not yet in a position to broadcasters make. As a consequence, direct digital interface is now licensed • 9 MHz ‘low-IF’ input. production, particularly in studios. displace the old CRT. we think that in future studio galleries to Electrograph Delphi, and shows that • Linear output. In addition to the camera operator, However, this year the plasma will need to include at least one plasma with a bit of care, the plasma pictures • Less than 13 W consumption. many broadcasters employ a second display panel seems to have gained a display to highlight the different can be very good. person to point a directional antenna. significant foothold. Everyone agrees presentation that these displays will It is interesting to note that plasma Compact video coder This is an expensive option, and often that the technology of plasma panels is offer. Our experience is that directors displays are often designed based on • MPEG-2 MP @ ML. leads to comic errors if the two people maturing quickly and that prices will tend to make different edit decisions computer standards of pixels, and not • Camera-back mounting. cannot co-ordinate their actions properly. continue tumbling. The quality of when offered a large display for broadcast standard formats. If this • Digital video input from camera. The problem of picture break up display, resolution, colour and contrast monitoring – there is a trend towards persists, then all displays are likely to • MPEG audio coding. was partly solved by better antennas, range is now very good. Many more of a ‘film look’. In addition, some include some form of standards • DVB-ASI output. and it is this route which has provided manufacturers are reporting an active technical imperfections are much more conversion. Our experience is that • Less than 10 W consumption. the BBC with competitive advantage in market in this area. Optimists believe obvious on a plasma panel – we have some standards conversion is better the past. We have used carefully crafted that plasma displays will be the natural noticed that digital compression and than others. antennas offering pure circular choice for large displays within three watermarking are both more noticeable polarisation – a known method of years, and even the pessimists only on a plasma display than a CRT. Our avoiding simple reflections. We have disagree on the timescale. technical standards will have to reflect also used intelligent directional antennas. At a major meeting of the European the growing number of domestic flat But this was only a partial solution – Broadcasting Union at BBC R&D, we screen displays. it is not possible to completely explored the impact that these new The displays now offer the eliminate the characteristic displays would have on programme consumer the opportunity of high imperfections of analogue transmission. makers and consumers. Manufacturers definition television at home. In the supported the event with a good USA, high definition is part of the digital

32 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 33 technical architecture audio description for digital television capacity planning digital text, enhanced tv and interactive platforms schedule interface widescreen television

BBC R&D ANNUAL REVIEW 35 Newcastle- GLASGOW upon-Tyne

BELFAST

Leeds MANCHESTER

Nottingham

BIRMINGHAM

The BBC is a large organisation. To fulfil our obligations, we have Cambridge many national, regional and local studios, broadcasting through a wide variety of analogue and digital outlets. How can we deliver this diversity in a manner which is flexible, efficient, and which offers a CARDIFF common brand image, whichever delivery mechanism is chosen? The Norwich Systems Architecture – the interconnection of all the playout facilities, multiplexers and delivery platforms – is a key technical component in this challenge.

TELEVISION CENTRE BRISTOL The BBC launched its digital television BBC Public Service Digital Television Key: services on digital satellite in October services in the UK. During 1999, the DTT/DSAT primary distribution 1998, closely followed on the digital BBC launched several new BBC terrestrial television (DTT) platform in digital services, such as Path 1 November 1998. SInce then we have BBC Knowledge, and added radio to Path 2 been working to provide additional its satellite television multiplex. As a services and enhancements, and to consequence, we have reviewed and, DSAT secondary distribution prepare for the rollout of services on where necessary, modified the technical Southampton Plymouth and regional sustaining feeds digital cable and the emerging architectures needed for coding, Path 1 Broadband/DSL platforms. multiplexing and distribution to support BBC R&D is responsible for the these new services. Path 2 design of the technical architecture for Multidrop connections

36 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 37 We have had to ensure that the • Each platform delivers Digital and the different picture STATISTICAL Radio on the services multiplex and a complete BBC uses its available capacity to Text in a different way. aspect ratio. MULTIPLEXING satellite transponder English multiplex. The latter includes maximum efficiency on all delivery • Subtitles are processed • Compression coders for ON DSAT The BBC’s second transponder carries specially commissioned news platforms, so as to accommodate these differently on the terrestial and regional contributions For digital satellite, the regional services a mix of the National versions of programmes containing items from all new services without jeopardising satellite systems. would be installed locally. are returned to London, where they BBC ONE and BBC CHOICE, all regions. Services in these feeds are picture quality. • At launch, common coding are combined with the London material currently with constant bit-rate video coded at the final emission rates, to THE TECHNICAL at constant bit rate was to form the two transponder feeds. coding. However, here too changes avoid further decode/recode operations THE CHALLENGES OF ARCHITECTURE chosen for both satellite and This combination is essentially an have been made to the multiplex during and to minimise the bit rate required PLATFORM NEUTRALITY The BBC is both a regional and a terrestrial delivery. add-drop transport-stream multiplex. the past year to accommodate eleven for distribution. The UK-wide services The BBC aims to make its digital national broadcaster. There are Now, separate coding for statistical There is no other processing of the BBC radio services (BBC Radios 1, 2, 3, 4 are those with no regional variations television services available to the substantial differences in programming multiplexing has now been introduced regional contributions except for the (FM and LW versions), Radio 5 Live, (for example BBC NEWS 24), and these licence fee payer on all of the between England and Scotland, Wales, on one of the satellite-delivered conditional access encryption applied BBC Radios Scotland Wales and Ulster, are combined in the studio centres in available delivery platforms, and Northern Ireland – the Nations. multiplexes to accommodate an extra to all the satellite services to ensure BBC World Service and BBC Radio Scotland, Wales and Northern Ireland, terrestrial, satellite, cable and the Within England there are also lesser service – BBC Knowledge – a good correct geographical access to Asian Network). These are now all with their respective national regional emerging broadband/DSL systems. variations between London and the ten example of how the system services in accordance with available across the UK. Indeed, since programming to provide a regional The challenge is to offer viewers other English regions. architecture has had to adapt to meet programme-rights restrictions. all but Radio 5 Live are broadcast multiplex for each Nation. the same service propositions, with the We have tried to maintain this evolving requirements. The BBC uses two whole unencrypted, they can now be received At the launch, it was not possible to same ‘look and feel’, whichever regional editorial structure as far as The distribution architecture is transponders on the Astra 2A satellite. throughout most of Europe on any provide regional programming when platform the individual viewer uses. possible in the digital world. To do so based on ATM point to multi-point The English Region versions of DVB-compliant satellite receiver. available in the English Regions – the There are large differences in the data has required a rather ambitious and point to point connections, BBC ONE, BBC TWO, BBC CHOICE Introduction of these radio services necessary equipment was not available capacities available to the BBC on each architecture for the connection of all carrying MPEG-2 single and and BBC News 24 originating in London required new contribution feeds to be from the manufacturers and there was of the platforms and the respective our sites. Whilst the network for multi-programme transport streams. are statistically multiplexed along with arranged from the national and regional simply too much else to do. Until ‘gateway keepers’ have chosen different distributing our analogue television has The UK-wide and London-based the new BBC Knowledge service and centres where they originate. Most of recently, the English multiplex has been technical standards on the different been developed gradually over many services are coded in London for broadcast on one transponder. the new audio compression coding passed straight through at the English platforms for various services and years, the rapid development of new emission using a video bit rate of just Statistical multiplexing was equipment is sited at Broadcasting House. regional studios – so that all terrestrial service components. For example: services for digital delivery by satellite, over 5 Mbit/s. Regional services are introduced on DSAT during the summer A circuit to Television Centre delivers viewers throughout England have • A terrestial multiplex can terrestrial and cable has required a created locally, using sustaining feeds of 1999. It has enabled six services to the encoded radio signals, where they received the same programming with support a data rate of just over fresh approach. from London as a basis. The sustaining be conveyed within the capacity are multiplexed with the digital TV no regional variations. 24 Mbit/s, whereas a satellite Given the short time scales for feeds are coded at a higher coding rate originally required for five services programme services for transmission. Nevertheless, we created the transponder, can carry implementation, the availability (or lack of 8.7 Mbit/s, which gives a margin for coded at constant bit-rate, allowing original architecture with the necessary approximately 33.8 Mbit/s. This of) commercial equipment at the time, the subsequent decode/recode BBC Knowledge to be broadcast on the Providing English regional interfaces to allow English Regionality difference in capacity on the and the need for economy, three operation. It offers an acceptable satellite platform without the need to programming on to be implemented in stages after the two platforms, along with the key decisions were taken for the compromise between quality and bit acquire additional expensive terrestrial transmissions initial launch. When English regional requirement to support national initial installations. rate. The National centres at Glasgow, transponder capacity. It required the Our aim has always been to offer in opt-outs are available, these are coded and regional variants of some • The digital services would be Cardiff and Belfast also have individual modifications to the architecture for the the digital world the same geographical locally and inserted in the incoming services, means that it is not distributed independently of connections from London over which new coding and multiplexing equipment availability of all National and English sustaining multiplex, replacing possible to broadcast exactly the the analogue programmes, ‘clean’ programme material – without to be evaluated, installed and tested at English regional television services that the corresponding services sourced same multiplex of services or to avoid PAL coding picture regional branding or interstitial material Television Centre in time for the launch BBC viewers have enjoyed in the from London. The sustaining feed of video coding rates on the artefacts and to take account – can be transferred to a local server of BBC Knowledge. analogue domain. the complete English multiplex is different platforms. The systems of presentational differences for delayed transmission. To facilitate this, two sustaining retained, as this allows a service architecture has to reflect this. feeds are provided, the UK-wide

38 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 39 The architecture – National region regional connections.

sustaining feeds DSAT contribution

London

sustaining feeds

to be maintained – albeit without local direct from coders at Television Centre, programming, coding and primary English programme inserts – in the case of a and have implemented a dedicated link multiplexing are not necessarily carried region failure in the regional equipment. between Television Centre and their out in the same place. This separation During 1999, the equipment head-end operation in Bromley for this of coding and multiplexing makes needed to code and insert the purpose. We are considering offering statistical multiplexing very difficult to regional programmes locally in the the companies a full sustaining implement for the BBC’s terrestrial

The architecture – to English Regions has become available. multiplex. This would minimise the multiplex. Without it there is London. regions As a result of trials in Bristol, dependence of cable on the other insufficient capacity to convey an implementation of the infrastructure delivery platforms, thus minimising additional service such as Knowledge for English Regionality in all our cross-platform change control issues, without severely degrading the picture regional centres is now complete and and making it easier for the cable quality of all the services within the regional terrestrial services are on-air. companies to take our services. multiplex. Therefore, for the launch of ATM thr adaptation ee N BBC Knowledge, it was necessary to s a d t e io conditional e n Rollout of digital cable THE LAUNCH OF arrange for the service to be broadcast f s access DSAT1 g D encryption n S The three main cable operators (Cable within another operator’s multiplex, i BBC KNOWLEDGE

n A i T a t & Wireless, ntl and Telewest) are now BBC Knowledge, the BBC’s latest namely that belonging to SDN. s

u

s DSAT2 starting to roll out digital cable services. new television channel was successfully BBC Knowledge is just one of a number Progress is slower than we originally launched simultaneously on satellite of services coded and multiplexed MPEG-2 routeing London playout coding and and region suites routeing anticipated. We are working with these and terrestrial platforms on 1st June together by SDN, including Channel 5 multiplex multiplex DTT companies, to ensure that BBC digital 1999. Each platform presented its and a number of other commercial TV TV services are available to licence fee own challenges, which were services. As SDN code all their services UK l -wide loca payers on cable, and that the range of successfully overcome. at a single location they are able to BBC services and functionality matches On the digital satellite platform, employ statistical multiplexing to that available on the competing satellite BBC Knowledge is carried along with optimise the use of their available data The architecture – and terrestrial platforms as closely as other BBC services within a BBC capacity. High-quality video links were Nations. possible. This includes offering viewers multiplex. There isn’t enough capacity installed between the BBC Knowledge the correct national or regional version within the multiplex to carry an playout facilities in Television Centre of services for their location. additional service using straightforward and SDN’s coders and multiplexers, DTT UK-wide local Initially, the cable operators are constant bit rate video coding. which are located at Langley in DTT MUX sources services taking the majority of BBC services Therefore we introduced statistical Berkshire. BBC R&D designed the off-air from our terrestrial broadcasts, multiplexing. This makes it possible network architecture for delivering the and inserting them into their cable to accommodate six programme BBC Knowledge service to SDN, and regionally ATM multiplexes. This ensures that the services within the same total overall for monitoring the signals. opted presentation adaptation code services suite correct regional programming is bit-rate capacity which prior to the available in different areas. Services launch of BBC Knowledge had not available in the terrestrial conveyed only five services. national contribution decode multiplex have to be obtained from It was not practical to use statistical for DSAT the satellite multiplex and the cable multiplexing on digital terrestrial at companies have adopted different the time BBC Knowledge was launched solutions for this. Cable & Wireless in 1999. We said earlier that to retain have chosen to obtain these services the facility for English Regional

40 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 41 BBC R&D ANNUAL REVIEW

There are around one million people in the UK who are sufficiently visually impaired to have difficulty getting the full benefit from the pictures on television. Nevertheless they still tune in: they like the programmes.

In radio, we pay special attention to original programme so that the two the script to make sure that the provide a complete experience. A well listener can create their image of the produced programme dramatically events being portrayed, but in improves the experience that blind or programme television we rely on the pictures. This partially-sighted people get from puts partially-sighted people and blind their televisions. people at a disadvantage. Try just listening to the television one day. You HOW DO WE DO THAT? can get a good idea what is happening The production team creates a clean description just from the sound track – but there audio description track, which are times when the picture is is broadcast on the DTT network. In important. Then, people with impaired the receiver, a special plug-in card vision lose something from the removes the audio description, fade broadcast. For people with impaired combines it with the normal sound vision, audio description is the answer. and delivers them to the Audio description provides a listener’s loudspeakers. commentary which describes the scene We transmit data within the to the visually impaired. We leave the description signal which provides a programme main programme sound unchanged, but means of fading the level of the and description provide an additional sound component programme sound during description or channel. This is in mono and ‘clean’ and which provides an optional (it has no effects added). means of panning the description time During production, the challenge is around the sound stage to combine the commentary with the (e.g. left/centre/right with stereo).

42 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 43 video and programme sound UHF

programme sound mixed with description

AUTHORING normally carries stereo information, but passage being under the control of the There are various editorial issues in we place the description in the left programme maker. audio description. channel and coded fade and pan data • Key events have to be on the right. THE LEGAL FRAMEWORK output (programme described if they are not clear The studio signal is rugged, easy to In 1996, a Broadcasting Act came into and description mix) from the story-line or use and to monitor, and it survives force, regulating digital terrestrial programme dialogue. many processes (e.g. synchronisers, television in the UK. The Act states that • It is important not to talk over D-A and A-D conversion, rate changing, programme service providers will have the dialogue. Not only does it editing, compression, gain changing etc.). to make at least 10% of their confuse the plot, but some The producer controls the mix of programmes available with audio partially-sighted people may also conventional audio and description. description, by the tenth year of their have hearing difficulties. digital licence. remote control • Early experience with audio Coding In addition, the Independent description has shown that We have to be economical with our Television Commission has stated that stereo programme listeners think it is important capacity on the DTT multiplex. The the independent programme companies sound from receiver to keep the same voice for audio description signal is coded as must carry audio description, and have a series. MPEG-1 layer II mono (the same as a quota which increases year on year. A cost-effective prototype authoring used for Digital Radio) at 64 kbit/s. The BBC has made a commitment station for audio description has been The fade and pan information is to at least match the ITC’s developed at BBC R&D. It provides embedded with the audio description requirements on its public service user control of facilities to create the audio description, as user-data (the MPEG-1 specification networks. Today our target is 2% of description volume and the support data for the broadcast. already provides special facilities for programmes rising to 4% in the fourth It generates a file of description and such data to be carried, making it a year of operation. decoded time-codes, plus the fade and pan relatively simple process to combine description information and, optionally, a DAT tape the signals). AND THE FUTURE... of the full description track. The gross transport stream bit-rate One of the key issues is how to ensure There may be opportunities to link cost is then 73 kbit/s per described that the special receiver cards are audio description’s authoring tools with service. This could be compared available to the target audience. We those used for assisted subtitling. This with the about 260 kbit/s which have developed emulators for the will make it easier to identify gaps in would be needed to transmit a second additional decoder module to help the narrative where there may be stereo mix. develop the market but the small size suitable opportunities for description. of the market, means that it is unlikely decoded main The receiver that a manufacturer will be prepared to programme sound THE TECHNOLOGY Audio description requires an additional develop the equipment without some Distribution within the studio decoder module which is plugged into a form of advance order. The studio signal uses existing ‘common-interface’ slot in the DTT Third-generation receivers may infrastructure where possible. receiver. The receiver produces a have audio description built in. Until broadcaster’s user’s control of The description signal and the fade separate mix of programme sound and then, audio description may have a control of mixed volume and pan information are conveyed in description, with the level of small audience. mixed volume the studio signal as a stereo signal using programme sound during a described the well-established AES-3 format. This

44 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 45 PRESSURE ON CAPACITY understanding of developments in statistical multiplexing (as it is called) from one moment to the next so the Getting the right balance is difficult and a ‘bursty’ nature. Their bit-rate There is increasing pressure to make contemporary coding technology, uses a reduction in demand on one statistical multiplexer must have a fast requires evaluation across a wide range requirements can vary substantially the most efficient use of available bit- allowing us to evaluate state-of-the-art channel to satisfy an increase in another response time. There will nevertheless of programme material within the from one second to the next, from rate on every platform to allow the commercial coders on behalf of BBC as (‘robbing Peter to pay Paul’). Statistical be times when many or all of the statistical multiplex bundle for programme to programme and from BBC to add new service components part of a tender evaluation for statistical multiplexing a group of video coders channels are showing demanding considerable periods of time in order to programme genre to programme genre. (e.g. Audio Description), to expand multiplexing equipment. thus offers the chance of increasing the material. Experience has shown that ‘explore the envelope’ of possible Sometimes they require high peak existing services (e.g. BBC Text) or to The bit-rate required to code a average quality of a decoded video one evening there may be no occasions combinations. As more of the bit-rates in order to deliver information add new programme services to its given sequence of video to a given signal for a given (average) bit-rate. for which picture quality is significantly population become accustomed to to the viewer in synchronism with the existing digital multiplexes. This quality depends on a wide range of Alternatively it may allow the user to challenged. On the next evening, digital television, viewers will become associated main video and audio question is so important that the BBC factors. These factors include the achieve a picture quality comparable however, the combination of more aware of digital coding artefacts, components for a given service; at has a cross-directorate group activity (detail and movement) within with constant bit-rate coding but at a programme material across the bundle and isolated occurrences of poor other times they are largely inactive, monitoring the use of capacity, and we that sequence. One scene may contain lower average bit-rate. With pressure means there is often insufficient total picture quality may become and their nominal data capacity could have been responsible for maintaining lots of diverse moving details and so be to liberate bit-rate for new services or bit-rate in the bundle to satisfy the conspicuous and disturbing to the be temporarily assigned to other an accurate bit-budget for both digital difficult to code and thus require more service components, the emphasis has demands of the individual channels. public. Hence, further experiments are services or service components. For satellite and terrestrial services, than average bit-rate. The next, been on using statistical multiplexing to When this happens picture quality can planned during 2000 to balance bit-rate, example, the momentarily ‘spare’ identifying and where possible however, may be easier to code and reduce the average bit-rate be impaired on all demanding channels. perceived quality and BBC programme capacity could be temporarily added to implementing opportunities for bit-rate require less. requirements per service. The BBC runs reactive independent propositions. We will also continue to the bit-rate pool for video coding or savings. We also model the Our goal is to determine the point channels for its public services. It is evaluate new commercial tools used to convey background data consequences of new programme STATISTICAL MULTIPLEXING of balance between average bit-rate in a impossible to guarantee schedules and designed to provide a mechanistic services that are not so time critical. propositions and their practicability Coding video to a constant bit-rate given statistical multiplex bundle and bit rates. There are also notable times measure of ‘quality’, and aim to cross The bit rates we are considering are within (and without) the existing tends to be rather inefficient, as the bit- ‘acceptable’ picture quality. This we when several channels can be showing correlate such measurements with much lower than those for video, so digital infrastructure. rate chosen has to provide the desired have been doing firstly using an offline similar challenging material subjective assessments of the quality. statistical multiplexing of these For a television service the video quality for the worst case (high activity) coding and multiplexing system installed (e.g. Wimbledon and Olympic sports This will help the BBC deliver a additional services will not free component takes the greatest share of scenes. For all less-demanding in Television Centre (on loan from a coverage). These two factors lead satisfactory balance of choice and sufficient bit-rate to accommodate an the service bit-rate so efficiency savings sequences the constant bit-rate is more major manufacturer) and secondly by to high demands on the capacity of quality programmes to our viewers. entire new channel. Nevertheless, there often focus on video coding. The basic than sufficient. Nevertheless, there may running an experiment live on one of the multiplex. will be many possibilities for using such coding quality that can be achieved at be practical reasons for using constant the BBC’s DSAT transponders. The BBC’s expert viewers have, on OTHER SERVICES opportunistic data multiplexing particular bit-rates is of key importance. bit-rates in a multiplex. In principle, the more channels that occasions, considered that the balance There are other services we provide techniques to make more efficient use The techniques and commercial Across a number of video channels are included in the bit-rate sharing of picture quality has been which may contribute to more efficient of our available bit-rate capacity. compromises applied to video coding the ebb and flow of demand is usually bundle the less likely that all the unacceptable. Public sensitivity to use of the available bit-rate. vary between manufacturers, and are uncorrelated. We can therefore vary channels will demand high bit-rate coding quality on any of the digital Many service components, such as improving with each generation of the allocation of bit-rate to each simultaneously. The demands of a single platforms is largely uncharted and it is DVB-Subtitles and audio description equipment. We maintain an channel rapidly to suit demand. This channel change quickly and dramatically not easy to measure their impressions. (when available for a programme), have

46 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 47 Data services as part of television are nothing new. For example, the Teletext standard, taken directly from content providers such as the BBC way to analogue Teletext – a range of BBC’s CEEFAX service started nearly 30 years ago and now regularly analogue TV, for its information wishing to have a presence on all data content is broadcast cyclically, with attracts 15 million viewers each week. services. However, the satellite delivery systems. the opportunity to update, add, or platform is now migrating to a new remove content as and when required However, this success has created a offers for the delivery of improved new digital system using OpenTV. In contrast THE DIGITAL to reflect changing editorial propositions. legacy problem. Most World System exciting services via DTV. terrestrially, Digital Text was launched TERRESTRIAL DATA MHEG-5 is one of the outputs of Teletext receivers are based an early using the MHEG standard as agreed BROADCAST the Multimedia and Hypermedia Expert version of this standard, where the THE REALITY OF with the other terrestrial multiplex SPECIFICATION Group. It provides a lightweight (small functionality and presentation provided THE MARKET operators and service providers. Digital The requirement for any new memory requirements) means of is relatively inflexible. Improving Whilst the launch of DTV has created Cable will use HTML, the internet specification to support an open handling multimedia content, specifying CEEFAX without making existing an opportunity, ‘expectation standard, because it has a direct return receiver market, much like that enjoyed mechanisms for both object receivers obsolete, has proved difficult. management’ is an important issue. channel which offers exciting interactive by analogue television equipment presentation and user interaction. Of course, digital television (DTV) Receiver processing power is still options. All of these new digital systems manufacturers today, prompted the As one of The Digital Network needs new receiving equipment. This limited compared to a typical provide better presentation formats decision to base it on two international (TDN) members, we took a very active has created a unique opportunity to multimedia-PC and whilst bandwidths than CEEFAX, with improved fonts, (ISO) standards. role in the creation of a UK profile for introduce new platforms for the available may seem large they are still graphics, stills and animations, etc., but The grandly named Digital Storage data services. support of data services. DTV is based constraining due to the unidirectional they are incompatible with each other. Media – Command and Control around the MPEG-2 standard, which nature of the transmission path. Hence, the challenge is to provide (DSM-CC) is Part 6 of the MPEG-2 BBC TEXT provides a flexible data delivery Also unlike the encoding of video content creation and playout systems specifications (with Parts 2 and 3, video BBC Text is the BBC’s digital text service mechanism. This, coupled with and audio, which are almost always that can support the same Digital Text and audio encoding, being the best that replaces CEEFAX in the world of relatively powerful receivers with based on the ubiquitous MPEG services on these three platforms, known). DSM-CC is an extensive digital television. Digital Text is just the graphics capability, means that powerful standards, commercial and political providing a consistent presentation to toolkit for handling the transfer of first step on the road to fully interactive interactive data services are now pressures have led to a diversity of the viewer, irrespective of their chosen multimedia content from which one TV services, where video, audio and possible. The BBC is keen to exploit implementations across the different delivery platform. part, the Object Carousel, has been data are combined as part of a the opportunities such technology digital delivery systems. Digital satellite This diversity is clearly going to selected to provide a broadcast filing multimedia service proposition, with was launched using the World System create a significant challenge for system. In principle it works in a similar the prospect in the future of a return

482 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 493 channel from the viewer to broadcaster • Handling the introduction of new development of production tools and testing their prototype receivers. As a the viewer to augment the main video consistent feel to the BBC services for true interactivity. content types, such as images. the functionality of available receivers. result, it is now possible to view and audio components. Like all DTT across the platforms. Due to the differing timetables for The resulting Content Production quarter-screen video of one of our Digital Text services it is based on Cable operators tend to favour the rollout on the various delivery System (CPS), developed by BBC R&D, PROGRESS TO DATE linear services (e.g. BBC ONE, MHEG-5. However, the digital text use of ‘out-of-band’ delivery of text, platforms, BBC Text was initially went operational in November 1998 in The terrestrial version of BBC Text now BBC TWO, etc.,) within the display of content is synchronised with the exploiting the natural return path of launched terrestrially, although work on time for the initial launch of digital offers (Spring 2000) the digital viewer the Digital Text service. The viewer can playout and transmission of the picture cable systems. This is in contrast to the services for satellite and cable is now terrestrial TV and the BBC’s Digital over 800 stories comprising more than now enter and leave the independent and sound of the linear service, allowing embedded data services within the well advanced. Text ‘barker’ service. 1000 pages, with thematic navigation BBC Text service directly from/to any additional information to be overlaid at transport streams conveying the Our main requirement was to use Now a new commercially and attractive presentation formats, of the linear services – this is known as the appropriate point in the terrestrial and satellite services. This the existing CEEFAX editorial content, developed CPS is being implemented including full colour graphics such as channel association – a feature that was programme, if the viewer so wishes. allows the cable user to request which needed to be extracted and with our assistance to support weather maps and still pictures. introduced in March 2000. Thus it is possible to add an extra content from remote servers for formatted for re-use with minimum BBC Text services across all delivery Different services can offer their own The first true Enhanced TV service ‘dimension’ to the delivery of delivery specifically to their set-top human intervention. platforms, whenever possible using the distinctive branding, it is ‘simply’ a was broadcast by the BBC in June 1999 BBC Knowledge programming. box, in a one-to-one transaction. This had to be accomplished with same core source material. matter of providing the appropriate – a special service to accompany the Additional information in the form of Amongst other characteristics, this the minimum of impact on our live Longer-term techniques for truly content, templates and applications. BBC’s coverage of the Wimbledon 1999 text and graphics will be available to provides access to a potentially CEEFAX service, in time for an original generic cross-platform content Unlike Teletext, the broadcasters are Lawn Tennis Championships. the viewer for simultaneous display unbounded set of content, in contrast launch date of November 1998, without production and handling are being no longer tied by the technology to Unfortunately, at that time, there were with the video and audio, providing a to the terrestrial and satellite systems, complete technical specifications or investigated as a priority. producing services all looking roughly no suitably equipped receivers in the richer experience. This type of service where the content is constrained by the suitable test receivers. similar – there is real opportunity to public domain capable of decoding the could be provided for other channels characteristics of the carousel. There have been some THE BBC STRATEGY promote brand image and for the BBC signals. However, it was still possible in the future. Data services are being introduced interesting issues that have had to The BBC has a generic aim to offer to achieve significant competitive using prototype receivers to give live We developed a new architecture by cable operators as a ‘TV-Internet’ be considered: where possible its content on all advantage in terms of the service demonstrations off-air to the organisers for this service, ranging from source service comprising content supplied by • Mapping CEEFAX pages, delivery systems. This desire applies as propositions, content and functionality and public at Wimbledon – to much playout to the delivery of both the selected providers. We have established accessed using a three-digit much to data services as to the main offered to the digital viewer acclaim. This innovative service linear and Digital Text service connection architectures for the number, into a menu-driven, programme services. We have been in A BBC Digital Text service has been provided a wide choice of additional components to SDN on whose provision of BBC content to the various navigable hierarchy. discussion with all the major players on available on-air since the launch of the information, such as player profiles, multiplex BBC Knowledge is broadcast. cable platforms, and we have also • Ensuring that text edited using each delivery system. DTT platform back in November 1998. latest scores, and a host of other The service went live in April 2000. helped to adapt existing content for the CEEFAX fixed-width font However, due to the diversity of However, it was only possible to launch information including an interactive quiz For technical and commercial presentation within the different still renders without ‘over-spill’ platforms, standards, and the different the BBC Text service publicly a full year (local interaction with the STB), to reasons, the terrestrial platform has led proprietary systems currently operated using the new proportionally implementation timetables, there is a later in November 1999, when suitably supplement the BBC’s linear coverage the development and introduction of by the three major cable operators. spaced Tiresias font. (Tiresias phased ‘rollout’ in progress across the equipped set-top boxes and integrated of the tournament. All of these were the BBC’s Digital Text services. BBC ‘TV-Internet’ services on these has been specifically developed different delivery systems in the order: digital TV receivers were first made accessible simultaneously whilst viewing Nevertheless, we also worked on the platforms are likely to begin during the in consultation with the RNIB to terrestrial, satellite then cable. At the available to the public. quarter-screen video of match coverage systems for satellite and cable services Spring and Summer of 2000. aid legibility, especially for the same time the increase in service During the interim period we from one of the BBC’s linear digital too. Our aim is to try to use common visually-impaired.) complexity is also being phased as worked closely with our colleagues in TV services. content and applications, but to • Suppressing inappropriate visual new service propositions and the BBC to refine and improve the We also developed a new re-author as appropriate for these references, such as ‘See applications are developed and performance of the content and synchronous Digital Text facility to platforms with their different text CEEFAX Page 123’. tested. This is supported by our applications, and gave valuable enhance the BBC Knowledge service. standards – thereby minimising growing experience in the assistance to the manufacturers by This provides additional information to production costs and effort and giving a

50 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 51 new terrestrial platforms

satellite BBC internal

cable, PA listing

BBC Navigator

playout

broadcasting data service presentation planning strategic SID is the computer system that we have designed and developed to planning enable the BBC to create and deliver content to electronic programme guides (EPGs) on digital terrestrial, satellite and Online platforms.

Two principal services are supported: One of the main users of the system in schedules and triggers over various terrestrial and satellite services and to carry 11 radio services on the digital for the various platforms now delivering • The creation and delivery of the BBC is the unit which is responsible TCP/IP networks. Live web access is manage the successful delivery to these satellite platform, SID had the required BBC Digital services. schedules for electronic for the BBC’s EPG editorial output. also provided to the database. platforms. The database has been storage capacity to cope. But no single programme guides and They have to manage approximately Because there are so many different designed to accommodate a hierarchical BBC source could be found for the THE FUTURE associated metadata 30 live schedules for network and sources of information (the historical service structure, which will in future relevant basic schedules. We have SID is already a critical part of the e.g. genres, ancillary services, national television and radio. legacy of the analogue system), and allow the BBC’s complex series of defined and implemented a new broadcast chain. It is the key supplier of conditional access. The system is implemented as a there are several destinations, all of national and regional opt-outs to be interface between the SID database and suitable metadata to support home • Real-time delivery of ‘trigger’ traditional client – server model. Users which were set up using different modelled when the GUI is Broadcasting Data Services (BDS) to storage and virtual services. It will events to platform operators access the system through a custom- standards, SID is complex. Much of the further updated. enable the downloading over the ensure BBC programmes are promoted to support reactive ‘now/next’ written graphical user interface (GUI). complexity is bound up in the number BBC programme schedules tend internet of suitable schedules. in a way most advantageous to the BBC type services. Servers are used to run an Oracle of operational interfaces. to be very reactive to allow for In the multichannel environment it whilst retaining accuracy, a traditional database and support the delivery of SID has evolved considerably since programme overruns and schedule is essential to give viewers and listeners strength of the BBC. the initial system required to support changes when circumstances dictate. better ways of locating BBC content. SID will continue to evolve to the start of our satellite services. The A key requirement for the system is The BBC’s Navigator project is the handle changing requirements. The SID interfaces use launch of terrestrial television with its to manage schedule-timing variations response. SID has been chosen as the challenge is to ensure that these Inputs: PICS Import of ‘raw’ TV schedule associated regionality and new interface automatically by monitoring the playout source of data to support the initial developments are compatible across

Broadcasting data services Import of ‘raw’ radio schedules to ONdigital’s system resulted in the system and adjusting the sending of Online Navigator offering. Once again the range of platforms SID supports. need to redesign both the GUI and triggers to mark the start of SID has demonstrated its flexibility. We It has been suggested that since SID Compass Real-time monitoring of TV playout systems database. Terrestrial services were programmes accordingly. This facility have enhanced the GUI and database to now supports navigation generally, it Outputs : BSkyB Delivery of schedules and triggers for launched using a second database fed is particularly important now that carry the extra metadata needed to should be renamed Schedule Interface satellite services from content created for satellite. This new digital home storage systems are support the Navigator and we have for Navigation – SIN, now that sounds a ONdigital central collator Delivery of schedules for terrestrial services both for cross carriage and BBC multiplex interim solution was replaced in 1999 being introduced. We have now created a system to deliver the relevant lot more fun! Navigator Delivery of schedules to support when a single combined system with an implemented this functionality in SID information. It is expected that SID will BBC navigator CSM Insertion of service information directly into enhanced GUI and database were put for our network programmes. form the core of many of the BBC BBC digital TV broadcasts into service. This gave the users a single SID was initially conceived as a TV Navigator systems now being planned FTP Access to EPG schedules from applications application to create content for both only system. When the BBC decided to which are not broadcast critical

52 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 53 The BBC, in common with a number of other broadcasters, is generations of coders impose a half PUTTING IT INTO PRACTICE Descriptors transmitted by the transmitting an increasing proportion of its digital TV output in second uncertainty in the timing of The video decoders fitted in set-top broadcaster, is defined in the UK Digital widescreen, 16:9 format. Sales of widescreen TV sets are buoyant and the change of state of this flag. This boxes (or integrated TV sets) allow for Television Group’s D-Book. surveys have indicated that about a quarter of digital TV viewers are creates a disturbance whenever there the processing of widescreen pictures Whilst we still generate material in is a format change, e.g. between 16:9 so that they can be displayed on 4:3 all formats, and people have all types of watching on widescreen sets. However, most archive material and and 4:3, which is likely to be disturbing screens. The current options are either display, there is potential for things to many new commissions have to be transmitted in 4:3 format and, of to viewers. to display a centre cut-out (where go ‘not quite right’. Not only have we course, most digital viewers are still watching on 4:3 aspect ratio sets. information at the edge of the picture been directly involved in the Active Format Descriptors is discarded) or a deep letter-box formulation of the descriptors, we have Regardless of the shape of their TV format – the way in which the Active Format Descriptors provide which shows the full 16:9 frame but had to put a lot of effort into the screen, many viewers do not like to see producers and directors intended. supplementary signalling options. They with black bands at the top and bottom education of all involved. This has large areas of black and prefer to watch Thankfully help is at hand in the form of allow for the inclusion of information of the 4:3 raster. involved promotion of the standards, stretched or zoomed picture. Other additional signalling embedded within describing how the transmitted raster is Future decoders, available from late checking the conformance of set-top viewers prefer to see undistorted the digital TV data stream, to signal to filled. This includes an indication of the 2000, will have the option to process boxes, as well as providing explanatory pictures (whether full-frame or not) set-top boxes and integrated digital TV ‘active frame’ as well as whether this the picture to display a shallow (14:9) guidelines and test streams. regardless of what shape picture is receivers the various format/display includes a protected area. For example, letterbox which offers a good Nevertheless, the standards were being broadcast. options, so that taking into account drama is usually shot on a 16:9 raster compromise between the two options not always applied consistently, and this With a number of aspect ratio any viewer preferences, the but containing a protected 14:9 area currently available. has given rise to many of the problems options available to the broadcaster, a presentation is optimised. whereas sport is shot with a protected In addition to the processing experienced by viewers. number of picture processing options 4:3 area. Active Format Descriptors are available in the decoder, the TV display We are trying to work with the available in set-top boxes and similar SIGNALLING AVAILABLE used in conjunction with the aspect also allows manipulation of the picture industry and individual manufacturers to but separate facilities in TV displays TO THE BROADCASTER ratio flag to define appropriate shape by altering the scan in either the resolve problems where they exist. As a for manipulating the displayed picture, The MPEG aspect ratio flag behaviour for both the video decoder horizontal or vertical direction (or result of this work, all terrestrial set- it is little wonder that many viewers A flag is included in the MPEG within the Set-Top Box and the TV both). This would allow, for instance, a top boxes will be compliant following have expressed some frustration at broadcast signal which allows the display. This helps to present viewers 4:3 picture to be ‘zoomed’ so that the software downloads in early 2000 and the difficulty (or in some cases shape of the coded raster (16:9 or 4:3) with a sensible range of picture display viewer sees a full display (but of course satellite set-top boxes should become inability) of setting their preferred to be signalled. options. They also permit more the top and bottom of the transmitted compliant during 2000. picture display format. This does not give the receiver accurate timing of the processing, thus picture are cropped). Hopefully cable set-top boxes As broadcasters, we want to ensure enough information to be able to avoiding some of the ‘glitches’ that The intended behaviour of decoder should largely be compliant at launch. that our programmes are enjoyed by exercise sufficient control over the were common with systems using only and display, taking into account the the viewer in the optimum presentation display format. In addition, early the Aspect Ratio Flag. raster flag and any Active Format

54 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 55 digital television digital radio analogue spectrum planning

57 Chris Smith, the Minister responsible for broadcasting, recently • SFNs providing services to a new applications. This is one of the be very difficult and costly to implement. announced the Government’s plans for switching off analogue television region give better coverage if Government’s objectives. In practice, we would not be able to once digital television has gained a significant following. We are we adopt a modest guard We have examined the effect of match the analogue coverage using a investigating the ways in which we might make the transition from interval. MFNs which do not releasing either the lowest six ‘clean sheet’ plan. We would have to rely on significant guard intervals channels (in Band IV) or the upper make use of the existing analogue analogue to digital if this becomes policy. There is a legacy, which must do best. nine channels (in Band V). It is clear assignments, converting them to digital. be respected, of receivers in the UK market which can only receive a • MFNs need an absolute from our study that there is particular We have been in close contact with sub-set of the digital standards. minimum of four UHF channels value in retaining the channels in the Radiocommunications Agency, per multiplex, although this Band IV, not least because many of the who will be responsible for technical SPECTRUM PLANNING of options provided the greatest configuration has a fundamental high power analogue assignments use advice to ministers, and have carefully Switch over from benefit. As the starting point, 20 limit to the overall coverage. this band, and these can easily be explained the issues to ensure that well analogue to digital scenarios were identified for • MFNs need six channels per switched to provide digital services informed decisions can be taken. There are many options for an investigation in our study, including multiplex for expansion to near under internationally agreed rules. If the channels above 60 are all-digital plan. Many people assume options for national and regional complete coverage. They Following the Government released to the Government, there will that the most efficient way forward coverage for fixed, portable and provide coverage at least as announcement that it would consider be consequential changes required at is to operate all the transmitting mobile reception. The aim was to good and probably better than switching off all the analogue TV the 37 digital sites that use these stations on the same frequency refine a large number of possibilities the original analogue services. transmitters some time after the year frequencies. It should be possible to (the so-called Single Frequency and define a sub-set that will form the In general, our studies show that a 2006, we considered the options for provide adequate services using Network), but this does not fit basis of detailed planning scenarios minimum of six frequencies (8 MHz the BBC. The 80 digital stations now in frequencies released by switching off easily with the editorial desire to to be investigated. channels) per multiplex are needed to service cover fewer people than the analogue TV. This does create a offer different services in different Based on these scenarios, our provide universal digital coverage, entire analogue services. We need to ‘chicken and egg’ problem, which parts of the country. For this, studies to date have produced equivalent to today’s analogue find satisfactory ways of enhancing the means that switch over will have to be networks using different frequencies some interesting findings in which coverage. Based on this assumption, a digital service. a gradual process, rather than a ‘big for each transmitter (or Multiple elements of some scenarios appear total of 36 channels are required for an There are basically two approaches bang’. As frequencies are released, they Frequency Networks) are contenders. more beneficial than others. The key all-digital plan for six multiplexes – to an all-digital plan for the UK. The can be re-used for digital services in In addition, many of the parameters points are: significantly fewer than the 46 used first involves the conversion of existing nearby areas. In time it will then be of the transmitted signal can be • SFNs do not provide the in the current mixed analogue and analogue assignments into digital, as possible to switch off analogue varied, giving a different trade off universal coverage we first digital environment. internationally agreed, and the second is services there. between the ruggedness and anticipated, even with fairly long Therefore, it appears there may be to adopt a totally new plan. Whilst the capacity of the network. Our work guard intervals (for the type of potential for releasing a significant latter might seem attractive in terms of sought to identify which combination data rates required in UK). amount of spectrum (up to 80 MHz) for spectrum efficiency, it would, in practice,

58 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 59 We are also considering methods to planning process. Recent developments When the original UK digital plans development of a ‘Common Prediction Coldfield and Waltham DTT within a short period of the stations optimise future digital networks to have included: were developed, a cautious approach Method’ which met with the agreement transmitters. These showed up a few being brought into service, and provide coverage to portable receivers. • Programs for simple MFN was adopted in the planning whereby of all the planning organisations. The areas of good coverage where the remedial action has been put into place This work has revealed that a network channel allocation studies to interference to the analogue network adoption of this method by each of the prediction models had indicated a prior to a large take up of the services. infrastructure using around 130 assist in the preparation of was minimised. This resulted in planning organisations has meant that marginal service, and a number of other transmitters would provide useful, all-digital plans. different coverage for the different consistent coverage predictions can areas where coverage was poorer than Long distance propagation though not complete coverage. This can • Extensions to PlanTX (one of multiplexes, varying from 81% for now be achieved. predicted. In addition to providing A key element in planning our digital be achieved using the current UK our main coverage and the BBC’s services down to around We supply ONdigital with periodic valuable information to help improve services is a detailed knowledge of the variant of the DVB system, so there interference assessment tools) 64% for the lowest coverage updates of the latest coverage the prediction models, this information behaviour of long distance radio wave would be no reduction in capacity of to perform percentage-of- ONdigital multiplex. information. In order to assist our also enables informed judgements to be propagation. The signal strength from a the multiplexes. coverage calculations and to This variability in coverage has coverage planning, and to assist with made on whether proposed coverage distant station may be low for much of allow population counting. limited the potential audience for the the validation of the data supplied to improvements to the network are likely the time, but may suddenly rise by as European aspects • A new program to display terrain complete package of ONdigital ONdigital, a new feature has been to be cost-effective. much as 60 dB in particular types of The CEPT (European Conference of profiles, incorporating a full set services. Experience with the roll out added to our internal coverage display These investigations help to guide weather. Many of our service areas Postal and Telecommunications of high-resolution terrain data- has shown that a more aggressive facilities. It is now possible for us to the planning for future coverage are defined by interference-limited Administrations) has agreed to prepare bases and the latest version of the approach in the planning is possible to generate maps with overlays showing enhancements. For instance, contours. Early measurements were for an all-digital planning meeting to be international propagation tools provide better matching of the all the the number of multiplexes or plans international co-ordination difficulties based only on narrow band signals, held in the time frame 2003–2005. (ITU-R Recommendation P.370). coverage areas, without causing exceeding a user-specified coverage have been encountered with the and ceased at midnight (when most of Currently, digital television frequency A revised version of our Windows- unacceptable difficulties, and this enables threshold at each geographical location. Belgians for the Sudbury transmitter, the transmitters stopped broadcasting). assignments are regulated by the based interface to the Oracle a significant amount of re-optimisation Although much of the UK 81-station and with the Dutch for the Tacolneston For this reason, we have been agreement reached in Stockholm in transmitter database is proving valuable of the network to take place. plan is acceptable to neighbouring transmitter, for which work is now undertaking long distance propagation 1961. A new plan is necessary because in maintaining an accurate basis on This work is being undertaken in countries, we have now entered a in hand to develop technical solutions. studies of digital signals for the last the parameters and methods used at which to undertake calculations. collaboration with the ITC, ntl and phase of protection for the UK services A good knowledge of the UK few years. These studies have now that time, and in subsequent years as Some fundamental research into Crown Castle International and is (both analogue and digital) as Ireland, coverage gives us an advantage in entered a new phase by looking at a the analogue television networks ways to improve terrain-based independent of any decisions about the France, Belgium, the Netherlands and international negotiations. wider range of receiving sites (instead throughout Europe developed, are not calculation methods is underway as part implementation of analogue switch off. Norway start to develop their own of only Daventry). optimised to make the best use of of the DigiPlan collaborative project One problem that arose during this plans. In this respect, a potentially DTT helicopter surveys As well as testing typical spectrum in an all-digital scenario. with Surrey University. We are process was that the coverage difficult situation has been resolved in We have developed a method for propagation over land, we are testing a Preparations for the proposed optimistic that this will ultimately lead predictions of the different planning recent discussions with Belgium. Our measuring the radiation patterns of mixed land/sea path from the Dutch planning conference are expected to to a significant improvement in the organisations varied significantly from submission of detailed calculations for transmitting antennas using a helicopter transmitter at Goes. We have also take a minimum of four years. The accuracy of our prediction models, each other. Our prediction method has Crystal Palace, including portions of as the measurement platform. established a receiving site at groundwork is being carried out jointly which in turn should assist in making always been accurate within defined measured radiation patterns, has This enables both rapid and Guilmécourt in northern France, to by the EBU and CEPT, although the more effective use of the spectrum. limits. Nevertheless, we are always demonstrated to the satisfaction of all accurate evaluation of antenna radiation monitor the potential level of official conference preparations are striving to improve the accuracy and parties that it is possible for the Belgian patterns. Hitherto we had to rely on interference from Crystal Palace DTT likely to be carried out under the DTT ROLL-OUT AND this is facilitated by increased computer broadcasts to operate co-channel with manufacturers’ works tests, and were to our French neighbours. It is auspices of the ITU. COVERAGE EXTENSIONS power and availability of new Crystal Palace on Channels 22 and 25. unable to verify whether or not an somewhat surprising to discover that In the period April 1999 to March 2000, terrain/clutter data bases. The installed antenna was working properly. we seem to be the only organisation in Planning tools 40 transmitting stations for digital differences between our tools and Vehicle-based survey work This year helicopter antenna Europe carrying out such studies, Our extensive set of software tools is terrestrial television were brought on those of the other planners caused Although most coverage is now surveys have been carried out at a particularly as the results are of vital being continuously developed to reflect air as a result of our planning work. difficulties when trying to reach predicted by computer, vehicle-based further 44 digital terrestrial transmitting importance to future planning. the needs of those of us engaged in the This brings the total to eighty stations, agreement on which changes to survey work continues to be valuable. stations. The value of these helicopter providing BBC services to 52 million implement. A significant amount of Targeted coverage surveys were measurements is evident in the fact that people (81% of the UK population). work was therefore put into the undertaken of the Winter Hill, Sutton faults were discovered at 17 of stations,

60 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 61 Digital Radio is now well established. With the addition of one new Digital Radio transmitting station at Zouches Farm (covering the Luton area) the total number of stations rose to 29, providing BBC Digital Radio to 33.6 million people (60% of the UK population).

IF Digital Radio increases in popularity respect, it is important for the BBC to terrestrial Digital Radio. We think these in line with expectations, we will want ensure that potential future sites are frequencies may be better suited to to expand the availability of the service known and properly co-ordinated. meet the growing demands for local around the country. We have therefore The helicopter measurement radio services. If agreement is reached prepared a consolidation plan for an system has been used for assessing on the need for additional spectrum, it additional 15 transmitters, designed to digital radio stations. To date, 14 is likely that a planning conference will reinforce the existing UK coverage, stations have been checked, revealing be convened within a year to allot a filling particular holes in coverage. An faults in some of the installations, and further seven frequency blocks additional plan for ten stations to remedial action has been initiated. (multiplexes), in addition to the extend coverage in Scotland has also In the UK, we are using spectrum in existing nine. been prepared. Two additional stations Band III for Digital Radio. There is also As part of this process we are at Craigkelly and Hemel Hempstead are a tranche of spectrum available in working with the EBU to define the being considered to take advantage of L-Band (between 1452 and 1492 MHz) technical criteria for the allotment of particular circumstances that will enable which is being used extensively in some the L-band spectrum, and with the them to be built at low cost. countries. This band was originally Radio-communications Agency to DigitalONE, the new commercial allocated for satellite transmissions, but develop an appropriate UK position. radio multiplex, have proposed a similar there is now pressure to assign the The existing rules, agreed at the network of transmitters in Scotland. If whole band for terrestrial broadcasting. Wiesbaden Conference, are not ideal the BBC wishes to expand services to In Europe, the CEPT (responsible for for the smaller areas that are anticipated match, our existing proposals could be co-ordinating European use of for local coverage requirements. used to provide coverage to 75% of spectrum) is considering a conference the population of Scotland. In this to allot a greater part of L-Band for

62 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 63 Although there is now a rapid take up of our new digital services, our have produced an up-to-date set of licence payers, and will seek to licensing body. With the recent traditional analogue services still provide the majority of our listeners maps for our national Medium and scrutinise all new plans for major introduction of digital television services, and viewers with their quality services. These services are still being Long Wave services. building developments. In the case of it has been necessary to recreate the improved and re-engineered to provide more editorial variety and one wind farm, our assessment maps to cover not only the updated TELEVISION revealed that up to 100 people could analogue situation but also the recently better quality of service. Analogue television coverage be affected. Fortunately, we were introduced digital services. continues to be important – not able to advise that by re-alignment of Another ancillary service that RADIO for supporting additional services. The surprisingly as it is still our main the viewers’ receiving antennas towards operates in the broadcasting bands is Radio Wales, the English language contract for the review was awarded to delivery mechanism. an alternative transmitter, it should be the Digital Reverse Audio Bearer service for Wales, is now on air as a Aegis, who have drawn on our Many of the most recent possible to restore the reception of (DRAB) radiated from Crystal Palace. result of our recent frequency planning considerable database information. questions have been trying to resolve those affected by the wind farm. This allows the BBC to provide a work. Although Wales is extremely Their initial report was published at the anomalies, ensuring that we broadcast reliable and continuous communication difficult to serve, given the extensive end of March. We will give the report appropriate editorial content in SERVICES ANCILLARY link to our Outside Broadcast use of spectrum for other services and careful examination to ensure that all specific regions. We have provided TO BROADCASTING operations around London. the difficult terrain, Radio Wales FM is existing BBC public services (especially coverage maps showing the recent A significant proportion of the BBC’s This link has been affected by the now on-air with seven transmitters, and our national networks) are not London and South East split, and programme making facilitates, introduction of digital television. Our the network is now stereo-capable, compromised unnecessarily. advice on analogue television coverage including radio microphones and first thought was that it may have to bringing the coverage to nearly half of There has been much discussion in North Norfolk as the matter of talkback, rely on the shared use of be shut down because of the the population in Wales. recently about Medium Wave/FM regional programme anomalies in this broadcast spectrum. Because these introduction of new digital services There is continuing pressure for simulcasting and as part of the BBC’s area was discussed in Parliament. services can only operate on a at Reigate. However, as a result of new broadcasters to be given the future response to the FM Spectrum We are still one of the main non-interference basis to our studies, we were able to show chance to offer new radio programmes, Review. The situation has been a little sources of assistance and advice when broadcasting, it is necessary to that this system could operate without despite a shortage of frequencies. The confused because of the lack of new buildings and wind farms are provide means by which potential causing interference. Government has decided to review the information about FM and Medium planned and erected. Whilst it is not users can quickly assess the options use of FM spectrum. We helped draw Wave coverage for our BBC Local intended that we should bid for future available for a given location. up the terms of reference for the Radio stations. This has been clarified consultancy work relating to the impact For a number of years, we have review, which aims to address the (probably for the first time!) with the of buildings on analogue television provided electronic map-overlay data spectrum efficiency of existing services production of a set of coverage maps reception, the BBC is continuing in its to facilitate such assessments in relevant in Band II, and whether there is room for all these services. Furthermore, we role as guardian of the interests of its BBC departments and in the relevant

64 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 65 home storage digital radio mondiale new services, new radio mobile television licence protection new chip

BBC R&D ANNUAL REVIEW 67 Hard disc storage technologies, driven by the computer industry, are features. This information can be allows consumers and automatic ‘agent’ CD or DVD. It would be possible, cascading in price and capacity by factors that are almost supplied via broadcast channels and via technologies to have a common when supported by the broadcaster, to unimaginable. In the last ten years there has been a one hundred-fold a range of internet sources, and will be selection mechanism for programmes look at the sports results before the increase in the capacity/cost ratio of hard disc drives. Currently the accessible to both resident and already stored and for forthcoming news headlines, or to watch the items proprietary navigators operating in the material on the full range of channels, in Tommorow’s World in a different ratio is doubling every ten months. Industry expects this trend to home system. These standards will all using the same user interface. order. This information could be used continue, even to accelerate, for at least the next ten years. make it easier for the BBC to provide Consumers will also be able to ‘click’ even when watching ‘live’ sports events, information to home storage devices on trailers, selecting the advertised to review key moments of the game or Consumer products which use hard so, cannot find the recording television in a digital form for storage, and will help the take-up of this exciting content for recording in one simple to perform easy action replays at home. disc technology to store and organise afterwards in the mountain of and offer many of the features new technology by consumers. operation, whether this be for a single A key conclusion of the STORit television material are now coming unlabelled tapes beside the VCR. Then outlined above. programme, a series, or any other approach is the need to have a common on to the market. A cheap domestic there is the problem of not being able Some of these products rely on STORit, myTV AND THE ‘branding’ that the broadcaster wishes navigator to handle both forthcoming hard disc can now provide sufficient to record and play at the same time. retrieving programme guide TV-Anytime FORUM to describe. programme schedules and to manage capacity for over ten hours of People would like a product which information from a dedicated server The STORit project played a major role the internal disc space, rather in the broadcast quality television. Within allows them to return home after the which it contacts via a telephone in building awareness of the possibility Programme fulfilment manner that we do with our personal five years we may expect to see easy start of a programme and watch from call using proprietary protocols and and impact of home digital storage Once a programme, or series, has been computers today. This navigator is to use products offering between 250 the beginning whilst the programme is data. Others use information within systems. DAVIC (the Digital Audio- selected for recording, programme controlled by the user, and by and 500 hours, once again using a still being recorded. Telephone calls the broadcast signal provided by Visual Council) and more recently the fulfilment data will control the appropriate automatic functions – cheap hard disc drive. and other interruptions could be broadcasters. The BBC are working TV-Anytime Forum and myTV have acquisition process. No matter what performed by ‘agent’ technologies. Such technologies will surely have handled in the same way, just press with both types of product to been instrumental in producing new time the transmission actually takes Future developments will allow us to profound and wide ranging implications pause whilst watching live TV, and make sure our programmes are open standards for the supply of place, or even if the programme has customise the navigator using ‘plug ins’, upon the way that people watch TV resume from where you left off when easily accessible to customers with information to such devices. changed channel, the recording will be allowing users or designated service and therefore on the way that the the interruption is over. these devices. Programme material and information properly made. providers to provide a new user BBC will wish to brand services and As the price of hard disc In the standards field, BBC R&D can be provided for both conventional interface and agents which function schedule programmes. technology improves and broadcasting are actively working in collaborative broadcasts and the internet. Programme segmentation across the full range of navigation becomes digital, so it is possible to projects to develop open standards Some programmes may be transmitted features – including access to all of the HOME STORAGE offer exciting alternatives to the VCR for the delivery of information to Programme selection with extra information which allows system’s internal content. Many people find that the VCR baffles for recording TV programmes. In the home storage systems, for programme and decomposition viewers to move through the material them. They often fail to record the USA, companies like TiVo and Replay guides, delivery control, programme Providing input to resident navigator easily, rather in the manner that we can programmes they want or, having done offer boxes which code analogue segmentation and a range of new systems within the home environment, with the track selection features of a

68 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 69 Digital Radio Mondiale (or DRM for short) is a worldwide consortium prices. That’s the only way we can a mixture of source coding, modulation transmitted the signals and received which aims to develop and bring to market a digital radio standard for be sure that we will have listeners and error correction, multiplexing and them in typical reception conditions use in LF/MF/HF bands (otherwise known as the ‘AM bands’ or ‘bands on a scale which is meaningful to transmitter RF issues. around the world. below 30MHz’). World Service. This is difficult and the With our experience in rolling out DRM Consortium’s work therefore digital television and radio recently, we WHAT IS THE TIMESCALE? needs careful nurturing to keep the are well placed to understand the key DRM presented a general description DRM’s vision is to bring affordable national services overseas transfer to and reaching target areas some variously-motivated players working issues in the system design. of its system to the ITU in January digital quality sound and other services FM services, and the audience follows. distance away. towards this goal. We hope that they We have been assessing and testing 2000. The ITU requires more details to the world radio market. The prime To some extent, this situation can be will all find something valuable in it the audio coding proposals and the fine and the results of further laboratory BBC interest in DRM comes from the (and is) redressed by World Service by DRM TO THE RESCUE for themselves. details of the modulation system. These and fields trials by Autumn 2000. This BBC’s World Service, although we using local FM rebroadcast DRM will use digital techniques to: The potential market is vast if the are vital in a system which offers much is an ambitious and challenging cannot rule out the possibility that we arrangements wherever possible, but • Deliver a service which receivers are cheap enough – lower data capacity than many of the timescale. Fine details of the DRM may wish to migrate some of our this can only ever be a partial solution competes with FM in audio ‘small margins, large numbers, equals competing digital systems. We believe specification are still being resolved national services such as Five Live and to the problem. quality and reliability. reasonable return’. people will only change to the new and will continue to be polished, partly Radio 4 Long Wave to this standard. There already is a Digital Radio • Provide user-friendly assisted We are therefore considering what standard if there is a sufficient boost to in response to field trial results as they Short Wave transmissions have system in operation in the UK, but this tuning, schedules and might be the best way to ensure that quality and reliability. become available, with a detailed never been perfect – there are too is only suitable for the VHF and UHF other information. integrated circuits get made which are To help make the system easy to draft being complete towards the end many jokes about the quality of bands of frequencies. The alternative • Provide easy access to large cheap and consume the little power use, we are proposing an approach to of 2000. reception overseas for us to be method of delivering digital radio by coverage areas. that is acceptable in many markets. improve the use made of Alternative The intention is to reach the market completely comfortable with the satellite may be an option in future, but Frequencies (many short wave circuits in 2001/2 – also ambitious and standard. Programmes presently its commercial acceptance is not yet THE COMMERCIAL ISSUES TECHNICAL ISSUES are duplicated, transmitting on two, challenging, but necessary if delivery by delivered by short or medium wave do certain. The traditional delivery means For DRM to be of benefit to the BBC it Getting good quality audio (and a three or even four different frequencies). radio in the bands below 30 MHz is to not compare well in audio quality with for World Service, the short and has to be a worldwide solution – used modicum of data to support user- One of the early experiences we keep its place in the market. competing services delivered by FM. medium wave bands, has the advantage by many broadcasters, both national friendliness) through the narrow gained was in testing how some existing Now we are starting to see a decline of of remaining under our control and international, with receivers from bandwidth, poor-quality channels World Service transmitters behave with World Service’s traditional audience, as many manufacturers at affordable available is a serious challenge involving a representative signal. We have

70 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 71 Digital Radio is now a mature and established technology for delivering It can easily be carried on most digital Because TPEG is an open broadcast. These RTMs are encoded high quality audio services to all types of radio receiver, from car radios bearers and is particularly suited to specification, it is a key development and multiplexed into a TPEG byte through to hi-fi tuners. Thanks to continuing research in this area, Digital Radio as it is important to be that will create a truly open market for stream, which is cyclically spooled into able to deliver Traffic and Travel Traffic and Travel Information. This a data channel in the BBC Digital Radio however, Digital Radio now offers much more than simply ‘better Information to in-car systems. For road competitive market will ensure that the multiplex. An internet service is also radio’. New types of service are being developed that make use of traffic information, the Road Traffic public will always have access to the provided which makes the TPEG Digital Radio as a pure ‘data’ channel which will take Radio into the Messages (RTM) application has been highest quality information. stream available directly from an multimedia age. defined. A single RTM contains various internet ‘socket’. fixed data fields, such as event severity BBC TPEG PILOT SERVICE TPEG TRAFFIC AND to answer the important question: and message generation time, together A pilot service was set up by the BBC Receiver TRAVEL INFORMATION ‘How do I get from where I am to where with a number of RTM Components. at the beginning of 1999 to transmit a The BBC has developed a ON DIGITAL RADIO I want to be, avoiding any problems RTM Components describe the features TPEG service on Digital Radio. demonstration TPEG receiver as a With the recent advances in navigation en route?’ of an event – such as accidents, Java ‘applet’ which allows it to be systems, the provision of reliable Traffic locations (i.e. longitude and latitude) Playout used to decode data from both and Travel Information has become an THE TRANSPORT and road works – and have a Traffic and travel content is provided by Digital Radio and the internet. The important component in the PROTOCOL EXPERTS hierarchical structure that makes it easy the BBC Travel Unit from a custom TPEG receiver decodes the RTMs development of Intelligent GROUP (TPEG) to describe events to an appropriate Windows application that creates a file from the TPEG stream and stores Transportation Systems. TPEG is an The TPEG protocol, developed by the level of detail. The protocol is designed of current Road Traffic Messages. This them in a local database. The RTMs openly specified, bearer independent Transport Protocol Experts Group, is a to be ‘machine readable’, and so it is file is then sent to the TPEG playout are then filtered (using criteria such protocol for carrying such traffic and simple byte-stream protocol that can easy for the receiver to present the computer over the BBC Intranet and, as location or severity) and displayed travel data and can be combined with carry a range of data to support information to the user in a range of the playout software uses the file to to the user as text messages or navigation aids and positioning systems Intelligent Transportation Systems (ITS) different ways, and in any language. create a database of RTMs to be indications on a map.

72 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 73 MULTIMEDIA web page that contain URL links to information to radio receivers. COFDM DIGITAL RADIO other web pages. When a web browser allows mobile receivers, such as car Digital radio already provides requests a web page from a web server, radios, to pick up the signal reliably, and interference-free, ‘digital quality’ audio the server looks in the set of HTML also means that the same frequency to your home hi-fi, portable and car files for the web site in order to find the can be used for all transmitters in a radios, but now it offers even more. By HTML file for the requested web page. network without causing interference. using techniques developed from the As web sites are usually just a set of Using one frequency for a network internet, Digital Radio can now deliver a HTML files that reside on a web server, covering the entire country means wide range of multimedia services. The it is now easy to see how we can use that there will be no need to ‘Broadcast Web Site’ application for the data carousel to create a service re-tune car radios as they move DAB Digital Radio gives service with HTML. We call it a ‘Broadcast from one transmitter’s coverage area providers the opportunity to create Web Site’ because, rather than having a to another’s. new and exciting services using the browser request specific information But the benefits of Digital Radio popular HTML format, but with all the from a remote web server, the files for are not confined to car radios. The benefits of a broadcast system. the whole web site are broadcast in the amount of digital information carousel. On a PC based Digital Radio delivered by a Digital Radio signal is How it works receiver, a special web server is used to sufficient to support a number of audio The key to broadcasting HTML content create a web site from the carousel services (about seven), known as a is being able to deliver a set of files rather than from a set of files – a multiplex. This, in combination with the using the broadcast signal – this can standard web browser (e.g. Netscape) Single Frequency Network (SFN), easily be achieved by using the concept can then be used to view the service. makes Digital Radio much more of a ‘data carousel’. In a data carousel, On an integrated receiver, native spectrum efficient (more services/kHz) the information for a set of files is software can be written to allow the than conventional analogue broadcast cyclically – hence the name – data carousel to be browsed directly. broadcasting. Because Digital Radio which means that a receiver can always uses a digital representation of sound get the data for a given file by waiting DIGITAL RADIO there is no interference and it is for the next time the data is broadcast Digital Radio, also known as Digital possible to deliver audio of the highest in the cycle. In order to manage the Audio Broadcasting (DAB), has now quality. Also, it is possible dynamically files carried in the carousel, a special been with us for some years. The BBC to change the number of services in the ‘directory’ file is also broadcast which network has been on air since 1995 and multiplex, which means that new allows receivers easily to detect any a new Independent National multiplex channels can be created to cover changes to the carousel. was launched on 1st October 1999. special events, such as football matches. Having established a mechanism for Local multiplexes are currently being Another important feature is the ability delivering a set of files using Digital licensed to carry both Independent to deliver simple text messages along Radio, the next step is to do something Local Radio stations as well as BBC with the audio, allowing both with them. Because HTML is a content local services. An important step in the presentation information and other format that was developed for use on evolution of Digital Radio has been the useful information (such as news, the internet, it is worth having a quick development of chip sets – which are sports, results etc.) to be provided. look at how the World Wide Web now ready for volume production. This Digital Radio can clearly offer works. On the internet, web browsers has enabled receiver manufacturers to more services with better quality – are used to access web sites that are launch products at competitive prices. but that is only half the story. The created using web servers. Web Digital Radio will offer many new flexible multiplexing and the ability to browsers identify content by using a and exciting types of service – but what deliver new types of service ranging Uniform Resource Locator (URL) that are the basic principles that make from simple (yet highly effective) identifies both the web server that is Digital Radio the best way to secure the text messages through to full blown ‘hosting’ the site, and which particular future of Radio? multimedia and Traffic and Travel content from within the site is required. Digital Radio uses a ‘spread Information services make Digital The content for each web site is spectrum’ technique known as COFDM Radio a new medium for the future basically a set of HTML files for each to deliver large amounts of digital of Radio.

74 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 75 Digital Television as we know it was designed to deliver a useful service and required extra demonstrations sufficient quality for news inserts – for different levels of ruggedness and to conventional receivers – sets at home, fed with signals from an to be organised. instance to interview a busy politician different bit rates. antenna on the chimney, or, for people nearer the transmitter, perhaps Combined, the MOTIVATE on the way to the airport. This service The close relationship between the portable receivers would also pick up a useful signal. Now Chris Smith, demonstrations have shown the world could be implemented now, subject to different modes means that it is easy to that it is technically possible to deliver availability of spectrum in any particular make one receiver that can receive all the Minister responsible for broadcasting, has indicated that he would digital services to mobile and portable area of the country. As part of the the modes of the specification without like to switch off the old analogue transmissions in the future and receivers reliably. Now we have to Open Days at BBC R&D, we much added complexity. Any receiver re-use the vacated spectrum. One of the questions is what should be consider what is the best use of spectrum demonstrated such a mobile chips on the market can be programed done with that spectrum. There are several broadcasting options, as – for TV to mobiles, more conventional contribution link. to receive a wide range of different well as re-allocation to other services. TV, or new high definition services. One of the important successes modes of the DVB-T specification. from the MOTIVATE project was the Broadcasters can choose to trade We have been looking carefully at As part of our work within DVB-T FOR CONTRIBUTION finding that diversity reception brings ruggedness against bit rate. The more extending the reach of existing MOTIVATE, we helped to stage a The MOTIVATE work highlighted significant improvements in reception of rugged, lower bit-rate modes will be services, especially to mobile and demonstration of mobile reception of the use of the digital terrestrial system the digital signals. We can make early suitable for mobile or portable portable receivers. This is a major IBC ’98 and carried out planning and for production purposes as well use of this finding, as we are building a reception, whereas the less rugged, topic, and we have therefore field trials for the demonstration of a as broadcasting. prototype diversity receiver for use higher bit-rate modes will be suitable collaborated with a group of digital television service on the trams of A vehicle equipped with an with radio cameras. The current for transmission of HDTV or a broadcasters and industry in Europe in Amsterdam at IBC in September 1999. interview position, camera and DVB-T proposals for digital radio camera multiplex of many programmes (as an ACTS project called MOTIVATE. The field trials were highly successful, equipment could be used as a mobile systems make use of the same currently used in the UK), to receivers showing that technically it works very studio. With the vehicle stationary and a transmission system (DVB-T) as is used using rooftop aerials. MOBILE RECEPTION well. The demonstration itself was put directional transmitting aerial on a for DTT broadcasting, and so could When the DVB-T specification MOTIVATE investigated mobile on by our partners in the MOTIVATE pneumatic mast it would function in benefit to the same extent from was being prepared in 1995, mobile reception of digital terrestrial TV which project, and it was seen as a very a similar way to the existing radio car. It diversity reception. applications were not seen as very could also offer broadband interactive successful demonstration, winning the could also be used as a base station for important. But since then in Germany, multimedia services. There is always a Production Solutions award for one or more of the digital radio BACKGROUND where there already is a high trade off between capacity of a service transmission technology for the cameras now being developed. In this The specification for digital terrestrial penetration of cable and satellite and its ruggedness. For mobile MOTIVATE project. configuration a DVB-T mode with high television used in Europe was prepared television, mobile TV has been seen reception, it is not possible to offer the We also showed mobile reception enough bit rate to allow post- by the DVB project. It is known as the as a unique selling proposition same capacity as the existing terrestrial of television in a minibus at the processing (say around 9 MBit/s) could DVB-T specification (T for terrestrial). for DVB-T. transmissions. Typically data rates up to 1999 BBC R&D Open Days – this be used. With the mast down and the To meet the different needs about 15 Mbit/s per channel (about was so popular that the visitors were vehicle in motion, a more rugged, lower foreseen by the many European 60% the capacity of the current almost fighting to get on the minibus, bit rate mode of the DVB-T countries, the DVB-T specification has terrestrial services) is available. specification could be used to give many sets of closely related modes with

76 APRIL 1999 – MARCH 2000 BBC R&D ANNUAL REVIEW 77 PROTECTING Meanwhile, we have significantly different technologies. For obvious THE BBC’S INCOME: improved the implementation of our reasons, it is unwise to go into details at DETECTION OF van-based detection system This uses a the moment, but these will allow much LICENCE EVADERS principle first used by the Post Office in more detailed information to be We believe that the BBC lost 1952, which also uses the magnetic field gathered about the TV set in question – £190 million during 1997-8 through to locate a TV set. Now the van has including whether it is receiving licence fee evasion. Last year this fell to onboard navigation equipment which analogue or digital! These new systems £160 million following a publicity can position the detected TV on a plan will be introduced into the van and campaign backed by nation-wide use of of the owner’s premises provided by an controlled by an integrated operator detection equipment. electronic Ordnance Survey map. A interface which makes it easy for the BBC R&D has collaborated with LSI Logic to produce the L64780 chip Evaders are tracked down with the laser range finder also measures the operator to choose the detection set for digital terrestrial television. help of handheld detectors, a fleet of distance of the van from the building. method that gives the best results at detector vans, and a national database Under favourable circumstances the any particular site. In many cases it will The chip set is now being used in DTT set top boxes by several major of licence holders. detection and location process can be be possible to name the channel that the manufacturers. BBC R&D has continued its collaboration with LSI Logic to produce A key element in improving our completed in 30 seconds. evader is watching, and to identify the a second generation chip, the L64781. position is the use of a wide range of The detection results are recorded make and model of his or her TV. This chip replaces the two chips that were required previously, which brings new technology together with existing automatically and include (even at night) All of the equipment is contained significant cost benefits. Additionally, the new chip removes the need for an detection equipment. From one a photograph of the premises, with within the van without exterior aerials. expensive external component (the voltage controlled oscillator) which was needed detection site to another, many factors automatic aiming of the camera in the This offers the choice of covert with the previous chip set. The market price for the chip is expected to be about vary greatly (e.g. vehicular accessibility; direction of the detected TV. The van’s operation, or of high-profile operation $12 in volume. the close proximity of several TVs, own database of local information can simply by emblazoning the van with the This chip has several new features including techniques for dealing with impulsive etc.). This means that no single be updated with information directly TV Licensing logo. interference caused by fridges, light switches, car ignitions, etc. detection method will be successful in from the central database, TRACE. The chip has been thoroughly tested at Kingswood and we and LSI Logic were all cases, and suggests that combining Switching the scale of the ‘live’ delighted when it worked perfectly first time. The performance of the chip has also several completely different Ordnance Survey map can enable the been measured and is so good that we estimate that if manufacturers used this new technologies could offer the best operator to navigate easily from one chip instead of its predecessor, then about one-and-a-half million more people would detection rate. potential evader’s premises to the next. be able to receive a good quality digital TV signal. Our first product was a handheld The equipment is controlled by a detector which locates a TV by looking PC, and is designed to be user-friendly for the magnetic field that results from so that minimal technical training is its picture scanning. This was followed needed in order to operate it. by a pocket-sized version working on Already in development are new the same principle. detection methods based on completely

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