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Is H.264 SVC the Video Conferencing/Chat Panacea? - Excellent Telepresence Industry Professionals Discussion
September 25, 2009 | Howard Lichtman
Here is an Interesting discussion on the Telepresence Industry Professionals Message Board. Join Telepresence Industry Professionals on Linked In to join the conversation.
"Is H.264 SVC the Video Conferencing/Chat Panacea?" -
1. Christopher Welch - Glowpoint
The recorded conversation is available now at the same link: http://tiny.cc/pnOHm ... until March 23, 2010 at 2 PM EDT. (One factoid from the event: More than 50 percent of the webinar participants had been on a video call within one week's time. The trend is good for us all.)
2. Sean Lessman - Senior Director Advanced Technologies at TANDBERG
First let me say, SVC offers some interesting things but it is very confusing the way it is being marketed.
This is an interesting topic that is certainly getting some buzz in the press lately. Unfortunatley there is a smear campaign being propagated against H.264 Baseline Profile, where the supporters of SVC are providing largely incorrect information about the H.264 standard to further their cause. To begin with, both H.264 Baseline Profile (what the 'traditional' VTC vendors currently use) and H.264 SVC are BOTH part of H.264 AVC -- H.264 SVC is Annex G to the H.264 AVC standard, you can download yourself and read at http://www.itu.int . They are both profiles. Neither are replacing the other, in fact last I checked there were 14 other profiles available under H.264 in addition to these two.
Many of the benefits being marketed right now by H.264 SVC supporters are also available within H.264 Baseline Profile. Multiple, additive streams and packet loss robustness are both quite possible within H.264 Baseline Profile and to say only H.264 SVC can support this is incorrect. Transcoding MCUs are not required under H.264 Baseline Profile. Lastly many of the demos you see from SVC products are proprietary, since the standards to allow for interoperability are still not available.
Much of the marketing seen today in favor of H.264 SVC vs. H.264 Baseline Profile (not H.264 AVC -- again this is the overall standard of which both are a part of) is actually highlighting the differentiators of one implementation vs. another (vendor vs vendor) but represented as one standard vs. another (H.264 AVC vs H.264 SVC -- even though SVC is part of AVC and they really mean Baseline Profile). The reality is both H.264 SVC and H.264 Baseline Profile are capable of similar performance but the H.264 SVC supporters have simply implemented feature sets that the traditional H.264 Baseline Profile products have not (even though the standard allows for it). Now that the boundaries of VTC calling are reaching outside of the organization through firewall traversal technologies and people are becoming more mobile in a VTC world, the demand for better performance on lossy networks is being heard. We expect you will see much work in this area within 'traditional' systems using H.264 Baseline Profile which has similar abilities, if not the same, to H.264 SVC with the additive benefit of being interoperable and more scalable with the installed base while not requiring gateways.
The discussion should really be "vendor A is better than vendor B" because of packet loss etc -- that is more realistic. Representing this debate as standard vs standard is incorrect and unfortunately misleading to customers that do not have responsibilities that include being video compression experts.
3. Adrian Hancock - Director of Technology at Videonations Ltd
The reality is that corporate deployments would typically benefit from high capacity networks and have no real need for this technology.
As such i would not expect Endpoint vendors to invest in the additional coding anytime soon.
After numerous tests with Vidyo & the Radvision Elite MCU with SVC one could conclude that SVC/H.264 Annexe G will be highly beneficial for desktop users on DSL technologies.
4. Howard Reingold - Director of Product Management at Glowpoint, Inc
These comments are consistent with the webcast I participated in on 9/22. I spoke about the tipping point for other technology advances. I highlighted some examples where these issues were overcome and the industry came together to reach the tipping point where everyone benefites. Only a few vendors have gone the route of H.264 SVC and it does increase the video quality over a non-QoS network such as the Internet and requires less bandwidth. I have come across corporate networks that could also benefit from the SVC improvements as well.
At the end of the day, having competing standards that do not interoperate will be detrimental to the overall growth in video technology.
One could also point to SIP and say it has similar issues. Although SIP seems to be progressing, there are a number specific extensions that have created these issues.
I always think about the VHS vs Betamax duel that went on for a number of years and hope the video industry does not go down that path more than it already has. Addressing interop and backward compatibility should be a key focus of everyone.
5. Sean Lessman -Senior Director Advanced Technologies at TANDBERG
It is very, very important for everyone to understand that SVC is an annex to H.264 AVC, it is not competitive to H.264 AVC, it is an additional profile to the H.264 AVC standard. There has been a large misrepresentation of this fact in industry marketing lately. Feel free to read the standard for yourself at http://www.itu.int .
When H.264 was first ratified in 2004 it had 3 profiles: main, baseline and extended. The VTC industry all adopted the baseline profile which was designed for real time communications (the others were designed for broadcast television, streaming etc.) Since then 12 more profiles including SVC were added to the H.264 AVC standard. H.264 SVC exists today as Annex G to the H.264 AVC standard.
H.264 baseline profile is also capable of multiple streams and the same performance in packet loss scenarios as SVC. However many of the vendors supporting baseline profile have not yet exploited these abilities of the standard. It is not factual or correct to say SVC offers better video quality than baseline profile. You can argue that one vendor's implementation of SVC works better than another vendor's implementation of SVC or baseline profile in packet loss situations. That would be a debatable point to make since most traditional VTC vendors can certainly do more with baseline profile to improve quality in lossy networks. But it is not correct to say one part of the standard is better than another in this aspect.
Let me say it again: H.264 baseline profile and H.264 SVC are NOT competing standards. I also think comparing this situation to SIP is a over simplification of the conversation and is apples and oranges. And it is certainly not the same at VHS vs Betamax -- since those were competing standards.
The reason there is no interoperability today is H.323 requires support for different video codecs within H.245. This is the 'capabilities' standard used to declare your product's abilities to decode different codecs. If there is no support within H.245 then there is no way to tell the far end how to handle the video encoding to send you the video. SIP has the same challenge with SDP. Second, many of the packet loss robustness benefits you see in these demos are actually proprietary packet loss techniques that are not in any way related to SVC. Since they are proprietary they will not work between vendors using different implementations. These techniques could be applied to any codec, even to baseline profile. But applying these proprietary techniques to baseline profile would diminish its ability to be interoperable as the far end wouldn't understand how to decode this information. The ITU/IETF (made up of many vendors to include the larger players in this market) are working to get SVC supported within the current handshaking/capabilities standards and when that happens you will start to see vendors moving in that direction in ADDITION to H.264 baseline profile, not replacing it. This will take a little time.
Until then, points to consider:
1. SVC is not new, the concept has been around for 20 years and goes back to the early MPEG days
2. Some vendors have chosen to focus on high video performance in lossy networks with little to no regard for interoperability
3. Some vendors have chosen to focus on the best video possible while maintaining interoperability
4. Any of the 'traditional' VTC vendors could also make a solution that was proprietary that only worked between like codecs and gave similiar or better performing video quality in lossy networks based on H.264 baseline profile (not SVC).
5. There is a lot of misrepresentation of the H.264 standard going on right now...unfortunately.
One thing is for sure, the need for better performance in lossy networks is being heard loud and clear and I expect you will see drastic improvements from all of the industry players.
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