Inside DVD: First Generation DVD Players Incorporate a Slew of
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Inside DVD: First Generation DVD Players Incorporate a Slew of Components
Mark Hachman
Don't blink: Today's DVD designs contain a jumble of discrete components that promise to shrink, blur, and meld together when second-generation DVD arrives by next Christmas.
Despite the film industry's reluctance to publish "perfect" digital copies of its content, a multi-industry body opened the gate to DVD production when a compromise was reached last November. Although there has been only a trickle of titles, the DVD industry is "educating" the public by providing the first working designs and programs to persuade consumers to accept the technology.
DVD manufacturers - largely leading Asian and European consumer electronics companies - are frantically developing, buying, and otherwise acquiring all the technology needed to develop the requisite components in-house.
"The educational process could take one to two years, until unit volumes reach critical mass," said Marty Golden, media representative and consultant with Philips Electronics Inc., Atlanta. "Until then, we'd like to 'eat our own cooking' by developing our own technology. But in the early stages of a market, it's not unusual to OEM other manufacturers' components."
While DVD spins its wheels in the early going, forecasts generally put this year's shipments of consumer players, or DVD-Video (DVD-V), in the 750,000-unit to 900,000-unit range. If DVD can sway consumers to abandon their VCRs, the market may reach San Jose-based Dataquest Inc.'s prediction of 14.5 million units by 2000. If not, then the estimate of 7.9 million units in 2000 provided by InfoTech Inc., Woodstock, Vt., may be more realistic.
Disks made for DVD hold 4.7 Gbytes of data, about 133 minutes' worth of movie data. Some DVD manufacturers are already including a second laser diode, anticipating the production of advanced media, such as double-sided disks bonded back to back that would eliminate flipping the disk over for longer films.
MPEG-2 video can be output in a 4:3 "pan and scan" format, in wide-screen 16:9 format, or in "letterbox" 16:9 mode. Audio can be encoded in a 5.1-channel Dolby AC-3, 7.1 MPEG-2, or linear PCM format. DVDs, Karaoke CD 1.0, VideoCD 1.1 and 2.0, CD-DA, CD-I, and CD-G (Japan) formats will work on these players.
Functionally, the data stream through a DVD-V player is relatively simple. A visible laser diode (VLD) beams red light at a 650-nanometer wavelength onto a disk spun at about eight times the speed of a CD-ROM via a spindle motor. An optical pickup head, governed by a spindle-control chip, feeds data to an amplifier or DSP, which feeds it to audio/video decode logic.
From there, the MPEG-2 data is demultiplexed into audio and video streams. Audio data is fed through a Dolby AC-3 decoder (possibly integrated through a DAC) and output to the speaker. Video data is decoded from the MPEG-2 format and then re-encoded for whatever display format is being used, NTSC or PAL.
An 8-bit or 16-bit microcontroller performs general system-control functions, such as controlling software navigation and regulating the servo-motor control.
The DVD format transport stream can deliver a variable bit rate of up to 11.08 Mbits/s of user data containing up to 10.08 Mbits/s of content and navigation data. The average bit rate assumed for a movie with three sound streams is from 3.5 Mbits/s to 4.7 Mbits/s, industry watchers said.
Memory is typically allocated so that a 16-Mbit SDRAM is paired with the MPEG-2 decoder, 3 Mbits of SRAM are paired with the data decoder, and a 1-Mbit flash chip serves as the BIOS for the system microcontroller, according to Mark Gaare, director of digital consumer products at Semico Research Corp., Phoenix.
For copyright protection, chip vendors also add a Content Scrambling System chip, a small component that protects against illegal copying of the data. The recent decision to encode movies by region is not supported by the current generation of DVD-V players, but they can be upgraded using the flash BIOS, analysts said.
For the next six months, product development for both DVD-V and PC-based DVD playback will proceed in lockstep (see sidebar, page 58).
"DVD has excellent potential to reshape the market," said Dale Ford, senior industry analyst at Dataquest. "It's the best example of convergence in recent memory. It offers the real possibility of drawing the consumer and PC markets closer together."
Until then, manufacturers are marketing virtually identical chips and chip sets for both the DVD-V and PC markets. With Intel Corp. processors potentially cutting into a dedicated logic market, when will chip vendors begin differentiating their products for each market?
"It's an interesting question," said Isaac van Kempen, director of the DVD business unit at LSI Logic Corp., Milpitas, Calif. "We really have to pay attention to the demands of the PC. From a design standpoint, for us it's not that important. I think only when DVD begins entering the [notebook] space, with the corresponding packaging and power issues, does that necessitate differentiation."
The first to market with a DVD-specific, "complete" chip set was Toshiba Corp. The company sampled the device in September 1996 for about $300.
The 12-chip chip set consists of a 16-bit CPU and three basic elements - the pickup unit, the physical block, and the logical block. The 16-bit CPU controls the signal flow of the overall circuit system. The pick-up unit, which contains two chips, detects the optical signal reflected from the disk and converts it to an electrical signal.
The physical block, which consists of four chips, controls the driver unit and pickup head, as well as signal amplification and processing to remove errors and assure correct data reproduction. The logical block, which consists of five chips, breaks down the digital signal into component elements. The video image signal is separated and decoded by an MPEG-2 decoder.
Toshiba's strategy epitomizes the challenges DVD designers face today. "The driving goal was time to market," said Daniel Lee, DVD program manager for Toshiba America Electronic Components Inc., San Jose. "Discrete components were easier to manufacture and debug. Reliability was at stake. We will decide to integrate down the line, but only where it is most efficient."
At one point, Toshiba was able to claim a lofty $100 for its VLD, presenting both a tidy revenue source and a production obstacle for OEMs grappling with supply and cost limitations. "Today, they're still in short supply," Gaare said. "But recent announcements by Sony for [devices] sampling at $50 help out a bit."
Toshiba's VLD sells for less than $10, said Joey Maniquis, product marketing engineer for optoelectronic products at Toshiba, Irvine, Calif. "It's a commodity part," Maniquis said. "With announcements from Hitachi and others, that $100 figure is history. Currently, supply exceeds demand."
Future developments, besides the 230-milliwatt to 250-mW laser needed for DVD-RAM, will be limited to optimizing the process used in Toshiba's fab in Hanaoka, Japan, and increasing the diode's brightness to improve the laser's positioning on the disk medium.
While chip vendors are holding some cards close to the vest, most will say that future development involves integration at two points: the physical and logical blocks. Theoretically, a single-chip DVD-playback solution could appear on a PC as early as 1998 (aided by host-based signal processing, which could process all MPEG-2 decoding functions, for example, using the host CPU), and a single-chip DVD solution perhaps a year later, said Alain Bismuth, director of consumer products for LSI Logic's DVD group.
In October 1996, LSI Logic introduced its L64020, a single-chip DVD decoding engine combining MPEG-2 audio/video demultiplexing and decoding, AC-3 decoding, on-screen display control, subpicture display, and a letterbox filter. By integrating functional cores into a single application-specific device, cost-effective integration can be achieved, LSI Logic executives said.
The quoted sample price is $35, Bismuth said.
"Essentially, it's a three-step process made up of a source-decoding block and a servo-control block," LSI's van Kempen said. "We first start out with the 64020 as is, with the necessary bridge chips, like a PCI bridge [to a PC] or a DAC. Then we integrate the bridge chips, and maybe the CPU in step two. On the other side, we currently have a two-chip servo controller/ECC chip set that we merge into one in the second step. The third phase is combining the source decoder with the controller chip."
But the target of choice for leading chip vendors remains the audio/video decoder. Market contenders are quickly trying to establish themselves against industry giants, including SGS-Thomson Microelectronics, for example, which was the leader in unit sales of MPEG-2 decoders, according to Dataquest.
But analysts say third-party companies face an uphill battle against the vertically integrated Asian consumer powerhouses.
Most observers foresee quick extinction for the market for discrete AC-3 decoders, in which Zoran Corp. holds a prominent position. The Santa Clara, Calif.-based company's ZR38600 is the only third-party chip included in the Toshiba chip set. Zoran previously added Head-Related Transfer Function, or 3-D sound, modules to its AC-3 discrete line.
"We've already laid out our strategy going forward," said Toshiba's Lee. "The only comment I can make is that we will integrate where it makes sense."
In tomorrow's designs, the term "decoder" will assume the presence of both MPEG-2 and AC-3 decoding, according to analysts.
Zoran has proactively integrated its ZR38600 AC-3 decoder with 3-D sound functions into its new chip, the ZR36700, called Vaddis. The part provides a dedicated interface to a DVD-DSP/decryption chip, as well as interfaces to 8-bit and 16-bit logic, to Zoran's VMI port, and to a single 16-Mbit synchronous DRAM. The chip will be in volume production in the third quarter, and volume pricing is expected to be less than $30, said David Anisman, director of marketing for MPEG products at Zoran.
The integration path is fairly straightforward, and vendors must either hasten product introductions or find ways to innovate.
Even with copyright issues holding up DVD production, some semiconductor manufacturers are struggling to catch up with their competition. A prototype DVD player from Philips, for example, incorporates an LSI Logic chip performing decode functions.
Philips is developing an AC-3 audio decoder and optical pickup chip to complement its HD61 MPEG-2 video decoder. But the company plans to have a complete chip-set solution "later this year," said Sunil Nethisinghe, new-business development engineer for Philips Semiconductors, Sunnyvale, Calif.
Not only is competition brutal, but resiliency is paramount. After battling its archrival ESS Technology Inc. in the Asian MPEG-1 market, C-Cube Microsystems has entered the MPEG-2 market with its ZiVA brand of MPEG-2/AC-3 decoders. The ZiVA chip features MPEG-2/AC-3 decoding (downmixed to two speakers), MPEG and LPCM audio decoding, subpicture decoding, on-screen display, VideoCD 2.0 decoding, and audio/video synchronization, plus the option to add 5.1-channel Dolby Digital sound.
"Half of the DVD experience is in the audio portion," said Lit Lam, director of DVD consumer marketing for C-Cube, Milpitas. "So adding 3-D sound capabilities, among others, adds a whole new dimension." C-Cube is also considering integrating the NTSC converter front-end chip, he said.
What's coming? Rewritable DVD is inevitable in the consumer space, and potentially could arrive as early as this summer for the PC. Thus, the next major wave of innovation will be in transforming a DVD player into a video encoder, where C-Cube and others hope to leverage their established technology. In addition, Microsoft Corp. still covets the PC as the focal point of the living room.
"I believe in the integration of DVD into other consumer products, maybe a set-top box, or perhaps in conjunction with something else," said Toshiba's Lee. "From a design phase, I anticipate a PC/TV convergence. DVD is well suited to a digital entertainment PC." |
