MPEG-4......................................................
February 09, 1998, Issue: 992
Section: News
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MPEG-4 close to multimedia market debut
Junko Yoshida
San Jose, Calif. - MPEG-4, the algorithm-agnostic wavelet compression technology geared toward the next generation of interactive multimedia applications, is poised to move from concept to concrete specification, backed by working silicon.
The Moving Picture Experts Group's MPEG-4 committee met here last week to hammer out a set of "usage profiles" for key MPEG-4 applications and could post the results on the Web (at drogo.cselt.stet.it/mpeg/) as early as today. With the newly defined usage profiles in hand, system engineers and chip designers should be better able to envision target systems and the design challenges involved in realizing them.
The first complete proof-of-concept silicon implementation could be realized next month: The Interuniversities Microelectronics Center (Imec; Leuven, Belgium) has slated a March tape-out for a wavelet-based codec chip. Separately, Toshiba Corp. detailed an MPEG-4 processor in San Francisco last week at the International Solid-State Circuits Conference (ISSCC)
Formal acceptance of MPEG-4 as an ISO standard is expected by February 1999 (the draft, announced in November, supports the H.263 streaming-video format). Jan Bormans, section leader of the multimedia image-compression group at Imec, said he expects the first MPEG-4 implementations to appear in the first quarter of that year, citing "interactively distributed games on the Internet" as an early application that will drive acceptance of the standard. Target platforms for MPEG-4 span from PCs to set-tops and mobile devices.
The new usage profiles-expected to include an Internet Profile, Mobile Profile and Broadcast Profile, among others-could act as drivers to take the technology from the research lab to the market. Each usage profile will support an application-specific set of MPEG-4 objects. The goal is to provide user-transparent compatibility among the various products designed for a given application area.
Each usage profile will require support for composition profiles for 3-D multimedia scenes, which could comprise not only audio and video objects but also text,
2-D/3-D synthetic objects and face/body animation.
A broadcast profile, for example, would support the blending of video images, Imec's Bormans noted. A mobile profile, by contrast, would focus less on video and more on support for such objects as air resilience and face animation.
Interactivity framework
The need for usage profiles to define real-world applications for MPEG-4 stems, in part, from the wide scope of the technology as defined by researchers. MPEG-1 and MPEG-2 defined audio and video coding for CD-ROM/Video CD and digital TV/DVD, respectively. MPEG-4 has a far broader reach; Bormans called it "a framework for compressing and representing 3-D multimedia scenes." As in the other MPEG flavors, video coding in MPEG-4 will be based on discrete cosine transforms. But the new specs call for wavelet compression for still images and 3-D texturing.
MPEG-4 is unique in that it embeds the behavior of an object into data to enable interactivity. It also provides so-called meta information about the delivery mechanism and client capabilities specific to the implementation. The goal here is to allow seamless scalability of MPEG-4 content.
In implementation, the Virtual Reality Modeling Language is viewed as a subset of MPEG-4, and"MPEG-4 extends VRML by adding support of real-time and remote audiovisual objects," noted MPEG convener Leonardo Chiariglione.
Wavelet silicon
Several silicon and system vendors have shown partial MPEG-4 implementations, for audio and video coding, but none has a complete solution, Imec's Bormans said. Very little work has been done, for example, on development of a wavelet-based embedded zero tree coder, though Bormans noted that such vendors as Analog Devices Inc. offer off-the-shelf wavelet filters.
The codec that Imec will tape out next month comprises an embedded zero tree coder and an arithmetic coder, Bormans noted. Imec has no plans to sell the roughly 40,000-gate chip, Bormans said, but the company believes it will have achieved the first proof of concept of full-fledged MPEG-4.
In Europe, meanwhile, Philips' TriMedia will be the only MPEG-4 demonstration chip under the European Union's Emphasis research program (see July 7, page 1), focusing initially on DCT-based video coding. The European effort had also targeted SGS-Thomson's Chameleon as an MPEG-4 demonstration vehicle, but SGS-Thomson has since canceled its Chameleon program to focus on joint work with Hitachi on the Japanese company's SH-based 64-bit microprocessor.
The MPEG-4 processor that Toshiba detailed at ISSCC integrates all functions presumed to be included in MPEG-4 Version 1 and keeps power consumption to 60 mW. Toshiba intends to sample the processor as a chip-set core sometime before final publication of the MPEG-4 standard next February.
Imec, meanwhile, says it has signed a number of partners for a collaborative MPEG-4 development program launched earlier this year (see Dec. 1, page 16), though it wouldn't identify the companies. Bormans said Imec is in negotiations with other potential partners and hopes to amass around six in all.
"The door is still open," he said. - Additional reporting by Yoshiko Hara.
Copyright (c) 1998 CMP Media Inc.
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