[xiph-rtp] Theora RTP payload format

[Phil Kerr]

Hi Steve,

Thanks for the comments and feedback.

Steve Kann wrote:

> Ralph Giles wrote:
>
>> On Mon, Apr 18, 2005 at 01:50:13PM -0700, Ralph Giles wrote:
>>  
>>
>> Our concern with defining profiles, like the 'VP3' bit I suggested 
>> has always been encouraging inoperable implementations that only 
>> support that profile. "profiles are useless" has been a common lesson 
>> of many specification designs. They make committee decisions easier, 
>> but then end you either implement the de facto standard or you don't. 
>> Those are the main reasons I remain unconvinced.
>>  
>>
> Maybe my case is an outlier, and maybe I'm just lazy :), but for this 
> situation, a fixed codebook would make life a lot easier. Since the 
> application is videoconferencing, the fact that the encoding format 
> would be (at the moment) limited to a fixed codebook would not affect 
> future decoders, and I would be keeping the on-disk recordings in a 
> format which does include the codebooks (*).

It certainly would make live easier, and for Theora it makes more sense 
than Vorbis.  But as soon as the protocols are re-worked to make them 
fixed someone will come along with a compelling use scenario that 
requires dynamic codebooks.

Trying to cater for such a wide range of uses isn't easy.

>
> At some point in the future, when better codebooks are developed, we 
> can improve the conferencing engine and such to support them, without 
> changing anything about the decoders.

The only problem is if the protocols fix in one particular manner (fixed 
codebooks) this will hinder developments for dynamic codebooks later.

The best option is to have a mechanism which allows the use of one 
codebook to be made easy, and the scaling up to be possible.

Cheers

Phil