Communicating and Expanding Visual Culture from Analog to Digital

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“Home Video” For The 21st Century Communicating And Expanding Visual Culture From Analog To Digital

V ICTOR C OMPANY O F J APAN, LTD.

Introduction In the 21st century, not only will TV TV broadcasts, the D-VHS format itself can broadcasts go digital, but a wide variety of work with standards other than MPEG. So JVC (Victor Company of Japan, Ltd.) information will be transmitted as digital sig- even if some other broadcast scheme is invented VHS in 1976. The history of home nals, and a household appliance that can adopted in the future, D-VHS will be able to video started then. By the end of 2002, record and store such information will accommodate it while maintaining compati- close to 900 million VHS video units would become necessary. bility with VHS. have been shipped worldwide (JVC esti- Also, it should be noted that among the D-VHS is a new proposal for household mates), with the software recorded using various types of storage media, tape media digital recorders in the 21st century. these VCRs comprising a gargantuan offers important advantages by way of its amount. high-storage capacity and superior cost- Characteristics Of Over 25 years have passed since its performance. D-VHS introduction, and now the environment in D-VHS, which enables digital recorders which VHS exists is changing profoundly. to take advantage of the high-capacity Bit Stream Recording Representative of this is the digitization of characteristics of tape, was developed as a One of D-VHS’s characteristics is that it TV broadcasts. In Japan, terrestrial broad- format based on the VHS standard. D-VHS utilizes bit stream recording, which is a casts will begin in 2003. Digital terrestrial allows the continuation and advancement of method of recording inputted signals, such broadcasts have already started in the the legacy created by VHS, and will not as those of digital broadcasts, on a tape United States and the United Kingdom impose a burden on manufacturers nor con- directly as digital bit stream data. No special along with digital satellite broadcasts. sumers. This is because of the enormous VHS, which has continually evolved and cultural value of accumulated VHS images progressed along with changes in broad- was given high priority in the development casting, will be required to meet the needs of D-VHS. of digital broadcasts while securing the To that, D-VHS adds the potential of visual link to the past. Moreover, with digital meeting the needs of future digital broad- broadcasting, various types of digital data casts. Although originally developed to can be transmitted in addition to images accommodate the MPEG signals of digital and sound. A solution for recording all types of digitally broadcast information in their original digital form, with the ability to play back the enormous number of analog VHS recordings, is D-VHS®. D-VHS makes possible a smooth transition from analog to digi- Evolution And Growth Of VHS tal, and is the next-generation home video JVC introduced the VHS format in 1976. Since then, the VHS-C compact cassette developed for format that enables the household visual use in compact and lightweight camcorders was culture created in the 20th century to be introduced in 1982; Hi-Fi VHS, which provided passed on to the 21st century. high quality stereo sound, was introduced in 1983; and Super-VHS, which achieved a higher level of User-Friendliness And picture quality, was introduced in 1987. In the Flexibility 1990s, Digital Audio was introduced to accommodate the satellite broadcasts that began then, and MPEG (Moving Pictures Expert Group) in 1992 W-VHS was introduced to record Hi-Vision D-VHS was developed in order to meet An encoding method used in storage media such broadcasts. Then, in 1997, D-VHS was developed the recording requirements of digital broad- as optical discs and tapes, as well as communica- to meet the requirements of digital broadcasts. casts while ensuring that the existing VHS tion media including broadcasts and telecommuni- Although VHS has grown and evolved in many video images that have been accumulated cations. Data volume is reduced through compres- ways along with the TV broadcasts, which com- sion technology. Video CDs utilize MPEG-1 where- prise VHS’s recording source, compatibility has thus far will remain accessible and will not as DVD and digital broadcasts use MPEG-2 to always been maintained with the basic VHS for- become obsolete. attain higher picture quality. mat’s recording and playback.

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processing or digital conversion (encoding) takes place, and the inputted digital signal is simply recorded onto tape in the D-VHS format. This is what is called bit stream recording. During playback, the same digital signal is routed through a set-top box (STB) or within the VCR which converts the signal into analog video and audio signals that can be reproduced on a TV, etc. Depending on the STB or unit, the signals may be output in digital form. Since bit stream recording itself does not include analog-to-digital conversion (encoding) or digital-to-analog conversion (decod- ing), the circuitry can be simplified to allow a reduction in cost. The maximum transfer/recording rate is 28.2 Mbps. Data recording capacity is 50 GB (using DF-480 cassette). This means that even if a 23 Mbps digital HD broadcast is sent along with 5 Mbps data in a sub car- rier, four hours of HD recording is possible. Or if the signal is 2 Mbps (level equivalent to Video CD), then 49 hours of recording will be possible per cassette. Achieving these capabilities will be dependent on the design Speed data rate) and LS (Low Speed data without retooling, large-scale distribution of the actual unit (product). rate) modes, which can be selected accord- can be done at reasonable cost. With the STD (Standard) mode at its ing to the quality or needs of a particular D-VHS tape is a high-performance ferric- base, the D-VHS format offers three record- broadcast. oxide tape developed on the basis of Super ing modes that also include HS (High Aside from manually selecting the VHS tape technology. On the cassette, there recording mode, in the future when picture is a D-VHS logo which signifies that quality quality information is included in the broad- level required for D-VHS guaranteed per- cast signal, auto selection will be possible. formance. A D-VHS cassette also has the ID Also, EPG-based programming and other holes on the bottom of the cassette. These benefits associated with digital broadcasts ID holes are used for the purpose of cas- will be incorporated. D-VHS adopts IEEE sette discrimination by D-VHS recorders. 1394 as the digital interface (also referred to as FireWire® or iLink® with DTCP being the D-VHS Mechanism terminology used for the interface incorpo- rating copy protection technology). So con- The D-VHS mechanism, which consti- nection to a TV or STB will be as easy as tutes the heart of a video deck, is essential- connecting an IEEE 1394 cable. ly the same as that of VHS video. A 62 mm diameter drum rotates at 1800 rpm. D-VHS Tape The difference is in the heads; for D- STB (Set-Top Box) VHS, heads with a narrower head gap for Equipment that receives digital TV broadcasts and The shape and dimensions of a D-VHS digital recording are used. And since the converts them to analog signals so that MPEG digital signals can be viewed on a TV. Also called cassette are identical to those of a VHS cas- recording track width is changed, the tape “digital TV adapter” or “digital tuner.” As digital sette. No special processes such as metal speed is also changed accordingly. broadcasts increase, they are likely to be incorpo- evaporation are used for this videotape, The recording track width is 29 microns, rated into TV sets and peripherals including VCRs. instead opting to utilize the ferric-oxide which is half the 58 microns used for VHS magnetic particles which have a proven Mbps (Megabits Per Second) track record and cost advantages. Ferric- M (Mega) denotes a value of one million. “bps” oxide magnetic particles have already stands for the number of “bits per second.” 1 Mbps means 1,000,000 bits per second. proven their reliability through VHS and Super VHS, and basically the same Super GB VHS manufacturing facilities can be used G (Giga) denotes a value of one billion. B stands for D-VHS. Since the mass-production facili- for Byte, which is equivalent to 8 bits. ties of tape manufacturers can be used

EPG (Electronic Program Guide) Ferric-Oxide Magnetic Particles A TV program guide that is transmitted along with Magnetic particles such as gamma ferric-oxide a TV broadcast. EPG programming will allow auto- which offer stable characteristics. In Super VHS matic recording of a program by selecting it on and D-VHS tapes, ferric-oxide with maximized per- the EPG. formance is used.

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SP mode. The tape speed differs depend- medium. D-VHS is ideal for use as a house- accordance with the desired resolution level ing on the recording mode. (See D-VHS hold data storage media. or processing speed, the norm for digital Specifications) broadcasts and DVD applications is Head azimuth is 30 degrees, which is the DVD And D-VHS MainProfile@MainLevel, which has a maxi- same as the Hi-Fi VHS audio head. For this mum transfer rate of 15 Mbps. The D-VHS reason, shared use with the analog Hi-Fi Gaining attention as a data storage STD (standard) mode, which has a 14 Mbps VHS audio recording head is made possi- medium is DVD-RAM and DVD-RW. The transfer rate, nearly matches this. ble. The standard STD mode uses two main characteristic of disks such as DVD- With the STD mode at its core, the D- heads, while four heads are required for HS RAM and HDD is their fast access speed. VHS format offers a number of other modes mode, and three heads for LS mode. On the other hand, tape offers an advan- to better accommodate a variety of situa- tage in the amount of data it can store. Even tions. Flexible recording is made possible Data Storage next-generation optical disks can only store because multiple channels can be recorded 20-30 GB of data on a single side, which is simultaneously, or the recording time can be Conventionally, home video was a medi- only about half that of D-VHS. extended, as long as the total remains with- um used to record images and sound. But In the future, it is believed that the media in the maximum 28.2 Mbps limit. in the age of digital broadcasts, the demands chosen will depend on the particular appli- Although the transfer rate for digital HD upon video will change. That is because in cation; those requiring fast access speed broadcasts is about 19 Mbps, there may addition to digitized images and sound, a will use disk, while those requiring large also be a possibility of 14 Mbps HD pro- wide variety of data will also be transmitted. capacity will use tape. Generally speaking, grams. It will be possible to record such Data-only broadcasts are also being planned. PCs will use disk while broadcasting will programs using the D-VHS STD mode instead In the case of images and sound only, use tape. Also, hybrid use of tape and disk of the HD mode. And with SD (Standard VHS will be able to record from digital is also a possibility. It may be important to Definition) broadcasts, programs transferred broadcasts, but the main advantage of D- note that virtually all hi-def professional at 6 Mbps can be recorded for 16 hours per VHS is not only its ability to record digital recordings are currently being made using cassette using the LS2 mode. images and sound with their original broad- the tape medium. Although the transfer rate differs by cast quality maintained, but also the ability It may also be important to note that not channel in digital broadcasts, on the aver- to record data along with it. all digital signals are equal. Just as there age it is said to be around 3.5 Mbps for SD Furthermore, in the future, there will arise are very noticeable differences between broadcasts. Since the STD mode has an a need to address information infrastructures high-definition and standard-definition input rate of 14.1 Mbps, theoretically it such as those using fiber-optical cables in broadcasts (which are both “digital” and would be possible to record three different addition to broadcasts. D-VHS will be able use MPEG-2), there is a major difference 4.7 Mbps channels simultaneously. to prove its power as a data storage device between the picture quality of D-VHS in the The ability to flexibly accommodate, that can record in their original state the var- HS mode (which is high-definition with a based on broadcast quality or priority of ious types of digital data that will be enter- maximum data transfer rate of 28.2 Mbps) programming, is a major merit of D-VHS. ing future households. That is because, and that of DVD Video (which has an aver- The 28 Mbps of the HS mode roughly corre- although with small amounts of data it will age data transfer rate of around 4.5 Mbps sponds to the data volume of one transpon- be possible to segment them while receiv- for a two-hour movie) although both use der of a broadcast satellite. For SD broad- ing them, by contrast with large amounts of MPEG-2. D-VHS in the HS mode has such a casts, it would be equivalent to six channels. data it is necessary to store the information large capacity that hi-def ATSC broadcasts first. at 19.3 Mbps can be recorded with no addi- D-VHS Recording There are many types of data storage tional compression. The DVD has a 720 x Method And Track media including HDD, MO, and DVD-RAM, 480 pixel (SD) picture versus a 1920 x 1080 Pattern and they are becoming increasingly large- pixel (HD) picture for high-definition D-VHS. capacity. However, only D-VHS is able to The difference in information density con- D-VHS provides three recording modes: offer the storage capacity and recording tained in a single picture is immense. STD, LS, and HS. Among them, the STD speed that lets it meet the demands of mode is the standard base, and the HS and recording future digital HDTV broadcasts Flexible Recording LS modes are optional standards. Since the with room to spare. And the tape medium ability to record and play back analog VHS used by D-VHS offers an extremely low cost The maximum data transfer rate for D- is mandatory, compatibility with current VHS per bit, so media cost is inexpensive. Also, VHS is 28.2 Mbps. Although MPEG-2 uti- is maintained. Track width has been set at it offers the benefits of being a removable lizes a number of different profiles/levels in 29 microns, which is half the width of analog VHS SP mode (58 microns). The tape speed DV And D-VHS will change in accordance with the record- Among the digital video technologies is DV, ing mode, but the track width remains fixed. which is used in camcorders. In order to record MPEG digital TV broadcasts on DV, it will be nec- D-VHS Recording Modes essary to first convert it to a baseband signal and D-VHS has three recording modes: STD then apply DV compression. Since DV and MPEG (Standard), HS (High Speed data rate) and LS use different compression methods, they have no (Low Speed data rate). The reason why they were electronic compatibility. not named HD (High Definition) or LD (Low DV, which offers the merits of high recording Definition) is because there is much variation density and compact size is the optimum media among the image quality (data volume) planned for camcorders. However the running costs of the for digital broadcasts, making it possible for some tape are high because of the use of (metal) evap- HD broadcasts to be recorded in the STD mode. orated tape. DV is a video camera format, where- The flexibility of D-VHS recording possibilities is as D-VHS is a bitstream recording format. expressed in the names of its modes.

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In analog video, one track records one Data, and Sub Data. Parity is the sector that the tape. This boosts the accessibility and field’s worth of visual information. With MPEG, carries error-correction codes, and in addi- operability of the format. however, compressed data is received via a tion to the Outer Parity there is also error- transport stream. So if, say, a single satellite correction information in the Sync Block, D-VHS Head transponder sends out six channels worth of which together provide robust error-correc- Configuration broadcasts, all six channels worth of data tion for accurate recording and playback. are received at one time. The Main Data sector contains audio and It is D-VHS’s simple and unique head With D-VHS, it is therefore necessary for video data as well as data received from configuration that enabled D-VHS’s flexibility the data within the transport stream to first data broadcasts. of recording, from HD broadcast recording be separated and reorganized into the indi- The Sub Data section carries the absolute to 56-hour extended-time recording. vidual channel streams. At this time, a time address as well as the chapter/index infor- A pair of heads placed diagonally on the stamp is recorded in order to ensure that mation necessary for search functions. These rotating drum is used for the basic STD the correct block is read during playback. are not sent from a broadcaster, but are mode recording. The LS mode includes the In this way, a sync block (SB) is created. generated internally and written onto the LS2, LS3, LS5, and LS7 sub modes. As Two sync blocks are equivalent to one data tape by the recorder during recording. does the STD mode, LS3, LS5, and LS7 all packet used in MPEG. Although 336 sync In order to allow these data to be read use just one pair of heads. blocks are positioned in the Main Data track even during fast-forwarding or rewinding, Though tape speed is slowed down in to be recorded on tape, more sophisticated Sub Code data is redundantly recorded on order to extend the recording time, the num- processing actually takes place. For instance, ber of times the drum rotates is the same as although search functions are optional to STD mode, and, per track, the recording the format, since the head will cross over rate of 14.1 Mbps is also the same. In the the track laterally, it is necessary to position LS mode, recording is done intermittently in the image data in a location where the heads accordance with the slower tape speed. will come into contact during search. The head is designed so that it does not The track pattern is, generally speaking, come into contact with the tape during the made up of three sectors: Outer Parity, Main drum rotation except only when actually recording onto the tape. Specifically, slow rate signals are accumulated in memory, and are recorded onto tape when they reach a level that allows recording of one track at 14.1 Mbps. The D-VHS format adopts the azimuth recording technique that enables accurate recording and playback of signals without any interference between neighboring tracks. Therefore, only with the LS2 mode was there a necessity to add one more head in order to prevent the head azimuth from being the same when recording tracks alternately using one pair (A, B) of heads. The same thinking is used with the HS mode as well. The D-VHS format is based around the 14.1 Mbps recording in the STD mode. In the HS mode, a two-track record- Tape speed and recording rate necessary for LS2 ing method is used. That is, the tape speed mode is half that of STD mode. It memorizes the 7 becomes doubled in order to record 28.2 Mbps data and records to tape at 14 Mbps, the Mbps, twice the data amount of the STD same as STD mode. mode. Though the amount of data per one track remains at 14.1 Mbps, recording of the doubled amount of data (28.2 Mbps) becomes possible by using two tracks. Therefore, a four-head configuration is used for the HS mode. The four-head configuration of the HS mode can also be applied to the three-head necessities of the LS2 mode.

Azimuth Recording Noise that is called crosstalk appears when the head reads signals of a neighboring track during HS mode divides a 28.2 Mbps data into two, and playback. Azimuth recording is a method to pre- records them in two STD tracks at 14.1 Mbps. vent crosstalk by angling the gaps of the two Recording time becomes 4 hours, half that of STD heads. The angles differ: ±6° for VHS video head, mode. ±30° for D-VHS.

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IEEE 1394 alone digital VCR, when it is combined with P.S. This technical white paper was prepared by DVD-RAM or HDD, it gains broader potential Victor Company of Japan, Ltd. and is published The D-VHS standard has adopted IEEE as a household digital recorder that can be herein with the company’s permission. 1394 as its digital interface technology. A used as a home server that offers both the IEEE 1394 terminal is beginning to be used huge-capacity characteristics of tape and as the DV terminal (iLink) of digital video the fast-access characteristics of disc. cameras and VCRs, and also gaining attention for use in home digital networks. COPYRIGHT © 1999 VICTOR COMPANY OF For its IEEE 1394 terminal, D-VHS uses JAPAN, LTD the same four-pin terminal as used in DV terminals. Just one simple cable enables transmission of all kinds of information including images, sounds, and data to an STB or television.

Digital Broadcasts And D-VHS

Digitization of broadcasts not only brings us high-quality images and sound, multi- channel and multi-functions, but also gives us a method to efficiently use the airwaves, which are a limited resource. This is not to imply that a digital video recorder is absolutely necessary to record digital TV programs. Since it is ultimately necessary to convert to analog in order to show images on a conventional TV screen, it is possible for analog VCRs, such as the VHS VCR, to record digital broadcasts after the signals are converted from digital to analog. However, the amount of information sent over-the-air will increase dramatically with the start of digital broadcasts. Though analog VCRs can record this information as a single TV program, the digital video recorder will be necessary to record all the information included in the data broadcasts, while maintaining the high-quality images and sound that are main characteristics of digital broadcasts. D-VHS is a way to record the data transmitted through broadcasts, making the most of its vast storage capacity. By taking advantage of the characteristics of tape media, only D-VHS is capable of recording HD broadcasts and also offering a maximum 56 hours of extended-time recording. Although D-VHS can be used as a stand- Visit WSR’s Newest Web Site HDD And Archiving Hard disk drives perhaps have unlimited potential www.DVHSMovieGuide.com to increase capacity and theoretically will enable recording of multiple HD broadcasts on a single hard disk space. This may become a trend in the future. However, hard disks being as they are, it will be difficult to remove them and use as archiving media due to manageability as well as running costs. In as much as you want to back up or archive data on your hard disk, the easiest, most For Everything You Want To Know cost effective and capable form of archiving ® ™ recorded HD content on a hard disk recorder in About The D-VHS D-Theater the future would be D-VHS. It is a perfect archiving solution even when HDD recording comes of Prerecorded HD Movie Platform age and a combination would be ideal.

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