PSA: stricter checking of SSRCs in the SDP
Philipp Hancke
If you are just using WebRTC in the browser and do not generate SDP yourself you can probably stop reading.
Chrome has started checking the SSRCs in the SDP a bit more in M115 (beta) and M116 already.
The first step was to reject offers or answers the specify duplicate SSRCs in ssrc-groups, e.g.
a=ssrc-group:FID 1234 1234
which now throws an error (and note that RFC 4588 already mandates using separate SSRCs).
The consistency of the ssrc-group lines with the ssrc lines is checked more strictly, i.e
a=ssrc-group:FID 4321 4320
will now check that ssrc lines are present for both SSRcs 4321 and 4320
a=ssrc:4321 cname:something
a=ssrc:4320 cname:something
For FID (rtx) such a check already existed, for FEC-FR (flexfec) it has been added.
I don’t expect much breakage but If you have concerns or questions let me know.