High-definition, multichannel digital broadcasts targeted -- JVC revamps D-VHS specs
Junko Yoshida and Yoshiko Hara
07/20/98
Electronic Engineering Times
Page 18
Copyright 1998 CMP Publications Inc.
Paris - At an event here that brought 800 of its worldwide dealers and distributors to the final match of the World Cup, Victor Co. of Japan Ltd. (JVC) announced completion of the full technical specifications for Digital VHS, adding further speed modes, with recording bit rates ranging from 2 to 28.2 Mbits/second.
With the revamping of the two-year-old D-VHS format, which allows up to six channels of digitally broadcast programs to be recorded simultaneously, the Japanese company hopes to overcome tape's image as a technological throwback and to sell the industry on D-VHS as the de facto digital bit-stream storage format for home recording of high-definition and multichannel digital TV broadcasts.
That strategy got a boost when JVC revealed a nonexclusive agreement with Canal Plus and Dassault Corp. of France to develop a D-VHS set-top and its applications. The deal is JVC's second major design win among service providers for its format; earlier, EchoStar Communications Corp. signed on to codevelop a D-VHS-based digital satellite recorder that launched in the United States late last fall.
D-VHS stores bit streams-incoming compressed broadcast signals-with the service provider's conditional access signals intact in MPEG-2 streams. That means a movie recorded on a D-VHS tape cannot be viewed on a screen unless first decrypted and decoded in a set-top box, thus making it difficult to copy movies outright.
That marries the solution to the chosen provider's descrambler and thus will require manufacturers to customize their D-VHS VCRs, at least until further standards are adopted by broadcasters and service providers. But the extra measure of copy protection makes D-VHS an attractive alternative as the consumer-electronics industry struggles to find a digital-to-digital home recording solution that will satisfy Hollywood studios' concerns over pirating of copyrighted digital content, said Hiroki Shimizu, senior managing director of JVC.
Further, even as satellite, cable and terrestrial broadcasters ready for high-definition and multichannel digital broadcasting, no alternative device yet exists for home recording of such programming. Not even the various optical rewritable record-ing media, including DVD , currently enable such recording. But in D-VHS, JVC has "designed an architecture that allows recording of up to six channels of digital broadcast programs simultaneously," Shimizu said.
He further noted that D-VHS supports analog VHS recording and playback and claimed that D-VHS therefore allows a smooth migration from the analog to the digital era by protecting "an important infrastructure: an enormous VHS tape library, a huge installed base of hardware and widely available blank tapes."
The industry estimates that "650 million units of VHS VCRs are in use in the world," Shimizu said. "D-VHS is the format that will digitize" that huge market.
That brash prediction is somewhat of a reversal for JVC. The company developed the basic D-VHS technical standard more than two years ago but has been relatively quiet about its invention to date, ostensibly because of concern that yet another tape format might seem irrelevant in an era of recordable disk media. Indeed, some in the industry dismissed the format as a mere tactical move by JVC to prolong the life of VHS.
But Masahito Fujimoto, managing director of JVC, said the company is confident that the revamped format is "both technically and commercially the most viable and most cost-effective gigabyte home-recording device." D-VHS provides a storage capacity of 44.4 Gbytes per cassette.
At the World Cup event, JVC president Takeo Shuzui positioned D-VHS as an ideal gateway and home media server in a digital universe in which broadcast and telecommunication services are converging.
Shimizu, however, acknowledged that he does not expect the arrival of D-VHS to forestall the market strides being made by other formats. "Disks and tapes have different features, and they can coexist," he said. "Both will be important package media in the coming century."
JVC completed the final D-VHS technical specifications with technological contributions from Matsushita, Hitachi and Philips, though JVC will serve as a single, one-stop licensing entity for the format.
Shimizu said the manufacturers that have agreed to support D-VHS thus far are Funai, Hitachi, Matsushita, Mitsubishi, Orion, Sanyo, Sharp, Sony and Toshiba in Japan; Daewoo, LG Electronics and Samsung in South Korea; and Philips and Thomson in Europe.
JVC America has been selling a D-VHS standard-mode (14.1-Mbit/s data-rate) VCR since December in concert with EchoStar, and Hitachi Home Electronics (America) has been selling a standard-mode VCR with a DSS decoder. JVC's own high-speed-mode VCR "may not be ready for the U.S. launch of terrestrial digital TV broadcasting in October," Shimizu said, but will likely be ready by next spring.
Multiple modes
The newly established high-speed (HS) mode of D-VHS, designed for recording high-definition digital images and multi-channel broadcasts, achieves a 28.2-Mbit/s data rate and enables recording of 3.5 hours of high-definition digital broadcasts. The low speed (LS) mode offers 49 hours' maximum recording for images and sound, but to assure compatibility with a broad range of future applications, the data rates and record times are selectable among four options: LS7, moving data at 2 Mbits/s and offering the full 49 hours of recording; LS5 (2.8 Mbits/s, 35 hours); LS3 (4.7 Mbits, 21 hours); and LS2 (7 Mbits,14 hours).
The previously defined, standard (STD) mode provides a fixed bit rate of 14.1 Mbits/s, offering ample headroom in relation to the bit rate of digital broadcasts.
HS mode video would employ the newly developed DF-420 tape to achieve 3.5 hours of recording. The LS mode could expand D-VHS application. The lowest data-rate mode, with its long running time, suits the VCR for use in surveillance applications. Most standard-definition TV programs have data rates of less than 7 Mbits/s and thus can be recorded in LS2 or LS3 mode, which respectively enable 14 or 21 hours of recording.
JVC realized the multiple-data-rate input by varying the number of recording heads.
D-VHS offers horizontal resolution of 1,000 lines, according to JVC. Conventional VHS, by contrast, provides about 240 lines of horizontal resolution; S-VHS offers 400 lines.
The low cost of the medium, its huge storage capacity and higher transfer rate offers advantages to consumers over those of competing rewritable media, Shimizu asserted. While the speed for random access remains a disadvantage of D-VHS, he said that the new version has an improved address function-capable of showing the exact position of recorded material on a tape.
The D-VHS VCR, combined with the set-top box of a service provider, requires a 32-bit microprocessor for housekeeping and running of a real-time operating system. Other chips are needed for the RF portion of the set top, D/A and A/D conversion, conditional access decryption and MPEG-2 decoding.
JVC has not yet launched a standalone D-VHS VCR without a set top.
July 20, 1998
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