Re: [AVT] I-D ACTION:draft-ietf-avt-rtp-atrac-family-03.txt

[Colin Perkins <csp at csperkins.org>]

Matthew,

On 23 May 2005, at 11:27, Matthew Romaine wrote:
> Colin, thanks for your input; I've implemented the changes  
> suggested as well as inlined a response to the auxiliary data issue.

Thanks!

> On 2005/05/19, at 5:02, Colin Perkins wrote:
> > On 18 May 2005, at 06:42, Matthew Romaine wrote:
> > > An auxiliary data section has also been added.
> >
> > The auxiliary data section was introduced in the -02 revision. I  
> > think the presence of this section is a mistake: it's better to  
> > signal extensions in the signalling protocol, rather than allowing  
> > undocumented auxiliary data. We don't typically allow such  
> > undefined extension fields in RTP payload formats.
>
> There have been a few requests from internal groups in Sony for  
> this part of the payload, as a) it minimizes resources otherwise  
> used externally (i.e. if another separate payload would be used),  
> and b) some groups have not solidified the parameters they might be  
> using.  These groups are requesting a mechanism to send data with  
> the payload rather than at, say, the SDP level.  Since there will  
> be a level of generality somewhere in the pipeline, I modeled this  
> section after the mpeg4 payload (RFC 3640) since that was an  
> accepted method.
>
> Is that enough of a justification?

No, I don't think so. This is one of the (many) problematic features  
of the MPEG-4 payload format, which I do not recommend copying.   
There are several unused bits in your payload header which can be  
used in a standard way from a revised payload format in future,  
should they be needed.

Colin

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