Re: [AVT] Comments on draft-ietf-avt-rtp-svc-07.txt

[Alex Eleftheriadis <alex at vidyo.com>]

Specifically regarding the S and E bits (your comment 13 below),  
their intended use is in conjunction with TL0PICIDX to allow for  
proper recovery of the lowest temporal level packets when errors are  
present. These bits, in conjunction with RTP seq numbers, enable a  
receiver to immediately detect if temporal level 0 data have been  
lost. The correct wording would thus be transmission order, not  
decoding order.

Note that as these three fields are used together, it does not make  
sense to separate them under two different flags (X and Y).

Although the decoding order issue is still being investigated, I  
would hope we have time before the next meeting to deal with this as  
well.

--Alex

On Feb 8, 2008, at 6:00 PM, <mike.nilsson at bt.com>  
<mike.nilsson at bt.com> wrote:

> I have read this draft up to the end of section 8, and have the  
> following comments. Mostly they are about clarifications and  
> editorial improvements to the text.
>
>
>
> I have not included any comments on the major open issue of cross  
> layer decoding order dependency, which I hope to be able to send  
> soon in a separate e-mail.
>

[snip]

>
> 13) S bit and E bit, page 23
>
> These definitions of start and end bits only seem to make sense if  
> NAL units of a layer representation have to transmitted in decoding  
> order. But this constraint does not seem to be specified anywhere.
>
>
>
> What is the intention?
>
>
>
> Should “decoding order” in the definition be replaced with  
> “transmission order”?
>
>
>
> These definitions could be much simplified using the term  
> “associated layer representation” as in comment 8.
>
>
>

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