More on Vweb's encoder chip...............................
eet.com
Startups refine Net-based video
By Junko Yoshida
EE Times
(11/13/00, 1:26 p.m. EST)
SAN MATEO, Calif. — Two-year-old Vweb Corp. will show an MPEG-2 encoder at Comdex this week that can adjust video bit rates on the fly to the available network bandwidth, addressing a central concern of OEMs and service providers pursuing the video-over-Internet Protocol market. The move puts Vweb among a small camp of system and chip companies that could soon include fellow startup Tiernan Communications, which claims to be just a few months away from rolling hardware that will handle MPEG-4 as well as MPEG-2 dynamic transcoding.
The quality of streaming Web video is limited today by the bandwidth available in the backbone, the connection speed, latencies caused by multiple hops between video origination sites and end-user terminals, and packet losses due to Internet congestion. Gerry Kaufhold, principal analyst at Cahners In-Stat Group, said solutions are needed that can adjust the streaming-video bit rate dynamically to fit the available range of delivery pipes at the best available quality-of-service. "Compress it once and play it back anywhere is the goal," Kaufhold said.
Some companies are attacking the problems at the network architectural level. Akamai, Digital Island and iBeam are focusing on edge servers; Inktomi and others are pursuing caching models; and Kasenna Inc., a Silicon Graphics Inc. spin-off, has devised a hybrid system of "push and pull" models represented in edge-server and caching implementations.
Others are focusing on a new generation of hardware that can handle dynamic transcoding and bit rate adjustment either on the network edge or in the backbone.
Vweb is aiming its first chip, the VW2000, at consumer systems, including personal video recorders, camcorders and Internet appliances. But the startup has also announced a development road map for a line card that will serve network routers, switches, caches and video services by combining the Vweb encoder with a network processor and other blocks.
That line card will compress video, create the appropriate network headers and dynamically adjust the video bit rate according to network type and network traffic congestion during video streaming, said Sho Long Chen, president and chief executive officer of Vweb. The chip integrates the intelligence to receive feedback from the network and then apply Vweb's motion-estimation and rate-control algorithms to adjust the video stream bit rate without dropping frames, Chen said. The line card will create tags for quality-of-service (QoS) to ensure distribution of the signal at the highest possible quality.
"Adapting to network congestion by reducing the number of frames is easy. That's what everyone else does," said Bill Reckwerdt, director of marketing at Vweb. "But our chip can provide a very fast rate of control, adjusting the bit rate [from one frame to the next] by allocating bits intelligently."
Chen said the video distribution scheme provides QoS across a broad range of networks. "It can adapt to everything from QCIF resolution at 128 kbits/second for ISDN and ADSL users to CIF resolution at 500 kbits/s and T1 resolution at 2 to 15 Mbits for ATM and optical-network applications." The technology is also extensible to MPEG-4 low-bit-rate compression, she said, for wireless-network applications at 64 kbits/s.
Meanwhile, Tiernan (San Diego), which pioneered a technology to transport MPEG-2 streams over asynchronous transfer mode, is working on "a hardware solution aimed at mitigating the storage costs and bandwidth requirements of delivering streaming media through the Internet," said chief executive Steven Bonica. "We are applying talent accumulated in the broadcasting industry to the Internet."
Tiernan's system, "designed to sit just before the last mile, will handle not only MPEG-2 but also MPEG-4, offering transcoding and rate changing," Bonica said. "This can be a standalone product or can be incorporated into a Web caching service." He said the hardware will arrive in a few months.
Satish Menon, vice president of Kasenna, said, "Dynamic transcoding has been talked about, but I have never seen it deployed commercially."
In-Stat's Kaufhold noted that streaming-media technologies developed by such companies as Real Network and Microsoft Corp. can require users to compress the video stream "in several different versions. That's because they want the encoded stream to be matched to different available bandwidths, depending on the delivery mechanism — T1, DSL, cable modem, dial-up or wireless — the user is using."
While nobody has commercial products yet, Kaufhold said he is beginning to hear about attempts similar to Vweb's. "And many of those efforts are made not by some garage operations but by companies that have had their knees deep into compression technologies. They know what the problems are."
Vweb is no exception to that rule. The VW2000 is Chen's third-generation MPEG-2 codec technology. Chen, who once worked at FutureTel, four years ago founded Stream Machine, an MPEG-2 encoder chip company for consumer systems. She launched Vweb after leaving Stream Machine.
Wu-Fu Chen, former vice president of technology at Cisco Systems, is a member of Vweb's board. The involvement of Wu-Fu Chen — who has launched a total of 18 networking startups, including Cascade Communications, Shasta Networks, Ardent Communications and Geyser Networks — is a strong endorsement of Vweb's technology, the company's president said.
The VW2000 uses 4 Mbytes of external SDRAM, features a 32-bit SDRAM interface and has less then 500,000 gates. CEO Chen claimed the offering is "by far the smallest MPEG-2 video encoder chip on the market."
The chip integrates a motion estimation unit; a motion vector refinement unit; a sequence-control unit, running on a 20-bit RISC core at 108 MHz; and a rate-control unit, based on a 24-bit RISC core at 108 MHz. Both RISC units are based on a homegrown processing core.
Patents are pending for the company's proprietary algorithms. The rate-control algorithm is said to track more than 60 parameters to deliver a more consistent group-of-pictures size, adapt to scene changes quickly and perform well at low bit rates.
The chip, designed for consumer systems, is priced at "under $30 in volume," said Chen. It is in volume production now at Taiwan Semiconductor Manufacturing Co.
When used to relieve traffic congestion in networks, the chip will require such additional blocks as a traffic classifier, FIFO bank and IP forwarding engine with Multi-Protocol Label Switching (MPLS).
Processor requirements
It will also need two separate CPUs: one based on a MIPS core running at 150 MHz, used for internal status and control for MPEG video services; and a network processor for the IP control plane. Reckwerdt said the company hasn't yet chosen a network processor for this implementation.
Chen said the VW2000-based line card is in the proof-of-concept phase and is slated to roll in the first half. Vweb's video distribution solution will provide "scalability and extensibility to new network protocols, like MPLS, and to lower-bit-rate compression techniques, like MPEG-4," she said. Although the initial product targets the MPEG-2 world, it will also handle the simple-profile level at low-bit-rate MPEG-4.
Kassena's Menon called Vweb's line card approach "interesting," but had reservations about its practicality, since each chip can compress only one stream.
Vweb's Reckwerdt countered that there will be four encoders per line card and that "our solution is scalable; users can just add more line cards. Usually, under an ordinary video-on-demand scenario, service providers will wait a few minutes before starting streaming video so that they can round out a group of people asking for the same movie."
Vweb's Comdex announcements will include a partnership with Geyser, a supplier of advanced multiservice optical networks. Geyser will integrate Vweb technology for cost-effective transport of video-over-IP, enabling service operators to offer value-added services such as streaming video with multicasting technology, video-on-demand and videoconferencing.
Vweb has also lined up nStreams Technologies Inc., a supplier of advanced digital media solutions, in a deal involving interactive video delivery over cable networks. Vweb will create solutions that compress video, create appropriate network headers and inject data into the cable network.
The VW2000 chip will be demonstrated at Comdex in a set-top box by connectME, a service of Independent Living Solutions. The connectME platform will offer video-messaging applications and Internet access for subscribers without requiring a computer. |
