It’s Time to Take Another Look at H.264 SVC


Scalable Video Coding has gained a great deal of market momentum in recent weeks.

Consider the following:

• Arkadin adding H.264 SVC video (licensed from Vidyo) to its web conferencing offerings

• Cisco leveraging SVC as the basis for its high-quality video offering within WebEx Meeting Center

• HP’s expanded line of video conferencing products based on Vidyo’s H.264 SVC technology

• KDDI’s announcement of SVC-based video services (also licensed from Vidyo) to deliver video conferencing as a service

• Polycom announcing support for SVC for mobile video to support tablets and video delivery across lossy networks such as mobile services and the Internet

Taken together, all of these announcements underscore the growing role of SVC as an alternative to H.264 Adaptive Video Coding (AVC) for delivering high definition video conferencing across any underlying network infrastructure. This is a development that offers the ability of video conferencing buyers to support high-quality video for remote or mobile workers without requiring huge investments in bandwidth.

Standards such as H.264 AVC and SVC define how video is captured, converted, sent among endpoints, and decoded (typically using SIP as the signaling protocol to establish one-to-one, one-to-many, or many-to-many sessions). Up until recently, most video conferencing vendors had standardizing on ITU H.264 AVC (Advanced Video Coding), commonly referred to simply as “H.264” (without the AVC designation). It’s worth noting that Microsoft and those who license its technology have taken a different approach using a proprietary codec, RTvideo, as a way of supporting reliable high-quality video over variably performing data networks. Meanwhile, Vidyo, along with Radvision, have delivered SVC-based products, touting the benefits of SVC in terms of its ability to support HD even when there is significant packet loss.

Ratified in 2007 as amendment G to H.264, H.264 SVC is based on the idea of slicing individual frames into layers, with each layer holding part of a single frame’s image. H.264 SVC sessions still provide high quality, even if end-points are only able to exchange a small percentage of layered frames.

But there’s a drawback among all the SVC momentum – lack of interoperability. The problem is that the current H.264 SVC amendment defines only standards for coding and decoding. There are no standards yet for areas such as transmission and error control, meaning that H.264 SVC solutions on the market today rely on proprietary approaches for these areas. The ITU Study Group 16 continues work on additional H.264 SVC standards, and more recently the Unified Communications Interoperability Forum (UCIF) announced a H.264 SVC interoperability committee, raising the hope that interoperable H.264 SVC solutions are on the horizon.

Meanwhile, most SVC vendors including Vidyo and Radvision offer gateways enabling AVC and SVC interoperability, enabling buyers to integrate their legacy AVC systems into newer SVC offerings, but AVC-based end-points still require guaranteed bandwidth and latency, and transcoding between AVC and SVC adds additional latency (and cost) to the equation.

The bottom line: evaluate emerging SVC offerings on cost and functionality, but also weigh the need to integrate SVC into legacy infrastructure.

Copyright © 2010 IDG Communications, Inc.

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