Hello, I've been doing a lot of research into this, but I figured I'd post what I've discovered so far here to see if there's anybody who knows more.
I have a server that does not support rtcp pli (FreeSWITCH), that ends up between two browser endpoints. When this server sends its offer, the only rtcp-fb present is: a=rtcp-fb:99 ccm fir Firefox answers with: a=rtcp-fb:99 nack a=rtcp-fb:99 nack pli a=rtcp-fb:99 ccm fir When Firefox generates the offer, a similar situation occurs, except VP8 is listed under 120, instead of 99. In the case detailed above, I'm not sure if the server is supposed to reply with an updated offer to settle the disagreement, but even so, Firefox moves on as if the other side did agree to those 3 parameters. I have not taken traces to identify if this occurs in the other direction as well (since the sdp is inconclusive about it), but it's possible. Once the call is established between browsers, video deteriorates until the keyframe refresh. This was not happening in Firefox 37, so it appears a change may have occurred to make Firefox more reliant upon the rtcp pli in version 38. In the same situation, Chrome only responds with 'ccm fir' and video keeps good quality throughout. There is (untested) code in FreeSWITCH for rtcp plis, but it was commented out later when it caused other video issues (fast source switches, as seen in conferences, would not work well). That was also a Firefox only issue, because Firefox always sent rtcp pli requests, where as Chrome could negotiate without it. The plis were, and still are, just not responded to by FreeSWITCH, but I believe it is now causing the deterioration. I'm not sure if rtcp pli is a necessity for all WebRTC endpoints at this point, and if so, I'll have to look into getting that working in FreeSWITCH. In terms of Firefox, shouldn't it take the rtcp-fb params of the offer into account when generating its answer? Thanks, James _______________________________________________ dev-media mailing list [email protected] https://lists.mozilla.org/listinfo/dev-media
