#59 Master pgs 22-55v2 2/27/02 1:18 PM Page 31 “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 possi- ble 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 accommo- date 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. Page 1/5 WIDESCREEN REVIEW • ISSUE 59 51 #59 Master pgs 22-55v2 2/27/02 1:18 PM Page 32 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 (encod- ing) 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. 52 WIDESCREEN REVIEW • ISSUE 59 Page 2/5 #59 Master pgs 22-55v2 2/27/02 1:19 PM Page 33 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.