Major players in the sector threw at least partial support behind MPEG-4 this week at the industry's annual National Cable Television Association convention here. Interest has become so intense that Cable Television Laboratories Inc. (CableLabs), an R&D arm of major cable network operators in the United States, has scheduled an MPEG-4 workshop for its members next month, said Christopher Lammers, CableLabs executive vice president and chief operating officer.

At issue are many elements that differentiate the business of interactive video in the cable world from that in the PC world. Whereas the PC can handle as many downloadable, plug-in streaming media codecs as creators can throw at it, cable boxes can't, for economic and architectural reasons.

Standardization has implications not only for the cable operators' systems but for streaming video technology companies, content developers and cable set-top silicon vendors as well. The chip vendors will likely be asked to modify existing MPEG-4 decoders.

"The amazing thing about streaming media today is how bad it is," said Jim Wood, vice president of advanced technology at AT&T Broadband. Cable operators seeking to leverage streaming media technologies over their networks "need two things: standardization on streaming media codecs and digital rights management. We at AT&T feel it's absolutely necessary for the industry to standardize on MPEG-4 and leave the holy war among RealPlayer, Windows Media Player and Apple's QuickTime behind."

Many U.S. cable operators have recently converted their cable plants to two-way hybrid fiber/coax infrastructures capable of streaming audio and video using either MPEG-2 transport protocols or Internet Protocols. As their cable modem business expands and next-generation advanced digital set-tops-integrated with cable modems-merge the IP and broadcast worlds, U.S. cable operators have a vested interest in the outcome of the streaming media debate. Lack of a clear standard would muddle cable operators' plans for low-bit-rate streaming media applications, enhanced broadcast services and interactive television delivered over the cable network.

"If we don't drive the standard now, our set-top boxes, constrained by processing power and memory size, will be brain-dead," Wood said.

Having a nonproprietary standard for a streaming media codec can also help build an optimized network infrastructure. Any streaming media can be delivered via either IP or MPEG-2 transport, said Prashant Gandhi, solutions architect for cable products and solutions at Cisco Systems Inc., but "a layer above that codec needs to be open for us to ensure the quality of service."

The U.S. cable industry wants to repeat the same success it pulled off with MPEG-2 almost a decade ago. "We were very smart then," Wood said. "We actively participated in the standardization process, took charge of bringing MPEG-2 intellectual properties into a pool, and succeeded in standardizing the broadcasting industry on MPEG-2 transport and turning MPEG-2 into a commodity."

Many in the cable industry made it clear last week that they are not considering MPEG-4 as a replacement for MPEG-2, which is currently used for broadcasting digital programs. What MPEG-4 does is "add significant improvements," said Mukta Kar, senior member of the technical staff for digital network architecture at CableLabs. MPEG-4, like MPEG-1 and -2, is a discrete cosine transform codec, but unlike its predecessors it is object-based. MPEG-1 was a frame-based codec for delivering a single program on a CD-ROM; MPEG-2 was developed as a frame- or field-based codec that lets digital broadcasting applications deliver multiplexed programs efficiently. Neither MPEG-1 nor MPEG-2, however, tackles interactive TV, synthetic objects or low-bit-rate applications.

MPEG-4 allows the cutting and pasting of video or synthetic objects, enhancing interactivity. The MPEG-4 video stream also becomes scalable when the network is congested, since it treats the frame as an object and can drop frames as needed. The cable industry's initial interest in the MPEG-4 standard is as a low-bit-rate streaming media codec. Cable operators could broadcast low-bit rate MPEG-4 streams from a headend using MPEG-2 transport, or MPEG-4 could offer point-to-point delivery of streaming AV via Internet Protocols.

"The industry today is streaming limited-video-quality clips to PCs," said Peter Ausnit, equity analyst at Prudential Volpe Technology Group. "But over time, it's entirely possible for cable operators to deliver almost an unlimited amount of high-quality video streams to TVs, with channels 1 to 300 dedicated to broadcasting digital TV programs and channels 301 to 3 million reserved for streaming high-quality video on demand."

AT&T's Wood observed that the quality of MPEG-4-encoded video, streamed as low as 300 kbits/second, "already looks very, very good."

But the cable industry's interest in MPEG-4 doesn't stop at low-bit-rate streaming applications. AT&T, for example, wants MPEG-4 for its "object-based elements," said Wood. Object-based technology would let content providers create personalized video streams for consumers, he noted. Advertisers, for example, could change the billboards shown in the background during hockey games or could change the color of a car in a TV commercial according to their needs or a viewer's preference.

At NCTA, the Philips booth offered extensive MPEG-4 demonstrations, including e-commerce, movie trailers, enhanced electronic program guides and personalized visual advertising. "MPEG-4 lets users choose objects and assemble them on a client," said Ahmad Ouri, vice president and general manager of broadcast and Internet delivery solutions at Philips.

Profiles undecided
Although most of the components of MPEG-4 are already set, industry consensus is still lacking on the best profiles and levels for the MPEG-4 standard as they apply to such uses as streaming video. The problem with MPEG-4 is that "it is designed to address so many different markets," said Peter Kaars, business development manager at Philips Digital Networks.

An ad hoc group composed of such companies as AT&T, Motorola, Scientific-Atlanta and CableLabs has been working for almost a year to develop an MPEG-4 streaming video profile. But CableLabs' Kar said the group has no consensus yet on such issues as how many objects the profile should be able to handle and the level of complexity it should address. For cable, a standard streaming video profile would ensure that the set-top could detect incoming MPEG-4 objects, to assure it could download software and to establish that its CPU could decode a number of objects. The box could then render those objects in software and overlay them on MPEG-2.

Kar declined to speculate how soon the industry might agree on a profile. But AT&T's Wood predicted that "MPEG-4 will be up and running in cable set-tops 18 months from now."

Proponents of proprietary streaming media codecs also claim they are making sure their file formats can handle standards-based codecs. Apple's QuickTime can handle MPEG-1; RealNetworks can accommodate both MPEG-1 and MPEG-2. At Microsoft, Steve Sklepowich, Windows Media product manager, even claimed the company's Windows Media Player is compatible with MPEG-4.

Compatibility question
But Microsoft has done its own MPEG-4 implementation, which considers only certain points of MPEG-4 profiles and levels, said industry experts. Its proprietary MPEG-4 implementation thus may not be compatible with other MPEG-4 decoders developed for set-tops by chip or consumer electronics companies. Further, the Windows Media streaming video format employs Microsoft's own file container and rights management scheme.

Two media processor companies-Philips spin-off TriMedia and Equator Technologies Inc.-stand to gain from cable's interest in MPEG-4. Those companies' solutions and Intel Corp.'s Pentium microprocessor are the only processors available today that can decode MPEG-4.

Video compression technologies continue to increase in video quality and decrease in bit rate. "A software-based platform such as ours can keep up with industry innovation," said John O'Donnell, co-founder and president of Equator. "All the advanced codecs can fit very nicely on our platform." An object-based media codec as complex as MPEG-4 is "not easy to implement, especially on a classic ASIC," said Ted Niday, Equator vice president of sales.