Created attachment 341253 [details] console screenshot Safari cannot set remote/local offer/answer from/to Opera. Using Opentok SDK we cannot subscribe to Safari and Opera from respectively Opera and Safari. But also using vanilla app https://appr.tc we can not perform a connection either. Please see attachment. It also occurs in Safari Tech Preview.
With Opentok SDK, we can still subscribe audio.
<rdar://problem/40553660>
The error message is similar to https://bugs.chromium.org/p/webrtc/issues/detail?id=4957 Do you have the offer SDP from Opera in apprtc? chrome://webrtc-internals works there which makes debugging easier. It looks like Opera 53 does not have h264 support anymore.
https://bugs.chromium.org/p/webrtc/issues/detail?id=9096 was a similar issue where Chromium 65 was missing H264 all of a sudden -- disappeared in Chromium 66. The best workaround for this remains to munge the SDP in Safari before setLocalDescription if the video m= line does not contain H264.
the lack of H264 is fixed in Opera 55 at least -- I don't think there is more action here.
Closing then. Please reopen if it is found out that interoperability is still broken with Opera.