Re: [AVTCORE] BUNDLE and same payload type in different "bundled" m= lines

Bernard Aboba <bernard.aboba@gmail.com> Wed, 09 March 2016 22:34 UTC

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From: Bernard Aboba <bernard.aboba@gmail.com>
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To: =?utf-8?Q?I=C3=B1aki_Baz_Castillo?= <ibc@aliax.net>
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Subject: Re: [AVTCORE] BUNDLE and same payload type in different "bundled" m= lines
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On Mar 8, 2016, at 8:47 AM, Iñaki Baz Castillo <ibc@aliax.net> wrote:
> 
> So the problem I report is basically the following:
> 
> If 100 participants join the same SFU conference and all of them send VP8 codec with payload 100 and same parameters, then each participant
> will be provided with a SDP containing 100 (or 101) m=video sections with a=sendonly, and each m=video MUST have a different payload type (rewritten by the SFU) for the VP8 codec (as they belong to different video streams from different participants).

[BA] What specific text in BUNDLE mandates this? In particular, the VP8 decoder can decode anything that the encoder can send, so the streams from the different participants do not require unique decoder settings. So AFAICT the SFU could send N streams to a given participant, each using PT=100, but with N distinct SSRCs.