RID/RRID for RTX

[Brian Baldino]

It seems that the focus around the implementation for RIDs has been for simulcast, but they're also the tool for RRID-based RTX.  I've been playing with creating a single RID on the client, such that it could use RRID for RTX, but the browsers don't seem to support this.

I think I've traced this back to a line in the WebRTC 1.0 draft here, which says:

"If the length of the [[SendEncodings]] slot of the RTCRtpSender is larger than 1, then for each encoding given in [[SendEncodings]] of the RTCRtpSender, add an a=rid send line to the corresponding media section, and add an a=simulcast:send line giving the RIDs in the same order as given in the encodings field. No RID restrictions are set."

I also found the place in the chromium code which enforces this here.

I happened to run into this when I was trying to test out RTX without simulcast with an SFU--eventually I'll have simulcast there so hopefully this won't be a problem.  But, if this is the case, how would one configure RRID-based RTX, for example, in a p2p call where simulcast wasn't supported?  

-brian

[Henrik Boström]

This sounds related: https://crbug.com/webrtc/10297

[walte...@gmail.com]

the bug https://bugs.chromium.org/p/webrtc/issues/detail?id=10297 is still open, so far we can only enable RTX by ssrc-group on the web browser side?