Examples sometimes don't load in Chromium

[mickel8]

Sometimes, when running echo and send_from_file examples, the video is not loaded (displayed). It looks like this problem doesn't occur in Firefox and Safari.

[mickel8]

It looks like there is a bug in Chromium - see https://issues.chromium.org/issues/351275970

TLDR; there probably is a RC in Chromium and something is not registered fast enough and the first frame is dropped. If we slow down sender rate, examples seem to work.

As a workaround, we might want to implement PLI forwarding in echo example and modify command for generating video file in send_from_file example to include more keyframes.

[mickel8]

Another workaround can be adding a=ssrc lines to the SDP offer/answer.

However, JSEP assumes that ssrc shouldn't be needed and instead we should relay on mid/rid. From the issue above:

JSEP pretends that one does not need a=ssrc lines and should not have them in favor of mid/rid header extensions. 
A lot of that is based on a myth about ssrc collisions which do not happen in practice.
If you decide to ignore JSEP please do not include label and mslabel as those are extremly old ways to do this. 
the ssrc-specific msid is a plan-b thing too and should no longer be necessary if you include a=msid:
You need a attribute name so a=ssrc:... cname 1234 is the most standard thing you may choose to include.

I would opt for relying on JSEP and not adding a=ssrc: cname until we find a real use-case