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Re: [AVT] Re: General extensible RTP header extension mechanism

On 2 Mar 2006, at 15:51, lazzaro wrote:
Dave Singer <singer at apple.com>
It has been pointed out to me that we ought to discuss the question -- do we *want* to make it easy to use the header extension mechanism in RTP, in general, non-colliding and yet non- registering ways? This draft permits that; is it desirable? 

I would say "yes".  I think we need to be
more cognizant of the fact that in addition
to the mature RTP areas (content-streaming,
VoIP), RTP is constantly being considered
as the base protocol for new application areas.

When folks are evaluating RTP for these sorts
of uses, and RTP doesn't meet their needs, they're
quite happy to break RTP in whatever way needed
to get the job done -- in a new application area,
there's nothing pre-existing to be compatible with.

I think a header extension increases the odds that
these sorts of "first-movers" define a new header
extension, rather than start modifying RTP or
RTCP itself to meet their needs ...

My concern is that this draft will encourage people to use an RTP header extension when a new RTP payload format or profile would be preferred, due to lack of understanding of the extension mechanisms we provide. That we are on our first standard header extension after 15 years of RTP development, should perhaps be seen as a sign that other extensions might be preferred in the majority of cases (this is not arguing against the SMPTE time code extension: that does seem to be a good use of the mechanism, but it's the only one I've seen to date).

Colin

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