Re: [AVT] Cross-layer decoding order

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

>> 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?
>
>That's an interesting idea. If there are sufficient 
>commonalities between the different payload formats, it makes 
>sense to use a common mechanism if such a thing is possible 
>(perhaps either an extension to the RTP header, or a common 
>building block used in different payload headers).
>

There are at least three existing drafts (the SVC payload draft, the MVC
payload draft, and the EVBR payload draft) that are common in this
regard. 

Having an extension to the RTP header is what Mike has proposed earlier.
If this is viable, it would be the cleanest solution in the long run,
and it will reduce a lot the document complexity for scalable codec's
RTP payload drafts. The only problem is when an RFC for this can be
available to enable SVC deployment. 

Having a common block used in different payload headers is not easy or
impossible to achieve, because the SVC and MVC draft are both based on
RFC 3984 and are required to be backward compatible to RFC 3984. If all
the scalable codecs are, like the EVBR codec, developped from scratch
and not based an existing codec, then a common buidling block in payload
headers is then easy to achieve. 

BR, YK

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