Re: [AVT] Comments on the major open issue ofdraft-ietf-avt-rtp-svc-07.txt, cross layer decoding order dependency

[<Ye-Kui.Wang at nokia.com>]

>Another weakness of the CL-DON method is that it does not 
>support NAL unit fragmentation in mode 1.  
 
You are free to use FU-A in the CL-DON mode when you use the interleaved
packetization mode. 

BR, YK

>-----Original Message-----
>From: avt-bounces at ietf.org [mailto:avt-bounces at ietf.org] On 
>Behalf Of ext Jonathan Lennox
>Sent: Tuesday, February 12, 2008 12:59 AM
>To: avt at ietf.org
>Cc: mike.nilsson at bt.com
>Subject: Re: [AVT] Comments on the major open issue 
>ofdraft-ietf-avt-rtp-svc-07.txt, cross layer decoding order dependency
>
>mike.nilsson at bt.com writes:
>> The major weakness of the CL-DON method is that it is not backwards
>compatible with the single NAL unit mode of RFC 3984.
>
>Another weakness of the CL-DON method is that it does not 
>support NAL unit fragmentation in mode 1.  RFC 3984 FU-A 
>packets cannot include a CL-DON, since mixing aggregation and 
>fragmentation isn't allowed.
>
>Though it's better to avoid it if you can, there are scenarios 
>where fragmentation is needed, i.e. video being transmitted 
>over a network with an MTU lower than the video encoder 
>expected.  If retransmission or FEC is in use, RTP-layer 
>fragmentation is hugely preferable to IP-layer fragmentation 
>of the RTP packet.
>
>
>More architecturally, I wonder if cross-layer decoding is a 
>question that should be addressed in a generic manner rather 
>than per-media.
>Several drafts have been presented recently for audio codecs 
>which do session multiplexing in a very similar way to 
>H.264/SVC, and they also need to be able to indicate a global 
>decoding order.  Should this be addressed as a generic problem?
>
>--
>Jonathan Lennox
>Vidyo, Inc (formerly Layered Media)
>jonathan at vidyo.com
>
>_______________________________________________
>Audio/Video Transport Working Group
>avt at ietf.org
>http://www.ietf.org/mailman/listinfo/avt
>
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