Opera sometimes does not play WebRTC video encoded in H.264

techmsgs

techmsgs

I have a media server which translates some videos encoded in H.264 to browsers via WebRTC. I tested various browsers (Firefox, Chrome, Opera, Edge) in various operating systems (Windows, Linux) and everything works fine in most cases, except for the case when Opera is run on a Windows 7/10 virtual machine in VMware. Opera receives the video stream but can't decode it for some reason.

I turned on WebRTC debug logs in Opera and got the following:

[2184:2312:1211/141911.062:INFO:decoder_database.cc(144)] Initializing decoder with payload type '102'.
[2184:2312:1211/141911.062:ERROR:h264_decoder_impl.cc(210)] FFmpeg H.264 decoder not found.
[2184:2312:1211/141911.062:INFO:generic_decoder.cc(216)] Decoder implementation: FFmpeg
[2184:2312:1211/141911.062:ERROR:decoder_database.cc(178)] Failed to initialize decoder. Error code: -1

When I run Opera on Windows 10 outside of any virtual machines, video plays successfully and I see in logs:

[6132:16856:1211/151144.100:INFO:decoder_database.cc(144)] Initializing decoder with payload type '102'.
[6132:16856:1211/151144.100:INFO:generic_decoder.cc(216)] Decoder implementation: ExternalDecoder

So I have two questions:

How is that possible that FFmpeg is unable to initialize H.264 decoder?
Why does Opera use different decoder implementations in different cases - FFmpeg decoder in the first case and some ExternalDecoder in the second case? What does this choise depend on? What does "ExternalDecoder" exactly mean?

I tried to solve this issue with no luck so far. I tried to do the following:

Uninstalled Opera and installed it again from scratch.
Tweaked various command line options containing "webrtc" in their names.
Disabled hardware acceleration in Opera settings.
Compared the list of video codecs installed in the non-working system with the codec list in a working system: they are the same!
Installed K-Lite codec pack.
Tried to play the same WebRTC video stream in different browsers using the same web client in the same system. Chrome and Firefox play video fine! Only Opera doesn't.
Tried to use a third party software for testing purposes: Unreal Media Server and its WebRTC player for browsers. I got the same results. WebRTC player works fine in Chrome and Firefox but doesn't play video in Opera.

Is there anything else I could try? Is there a bug in Opera? Or maybe VMware is to blame?

Opera 73.0.3856.260 (x64 for Windows)
Windows x64 Pro (Install date 16.10.2020)

sgunhouse

sgunhouse Moderator Volunteer

Real Windows has its own decoder (usually) and Opera uses that when available. I say "usually" because early versions of 7 and Windows 10 N do not.