audiomixer breaks the audio when trying to downmix

assigned to @vivia

Yeah, in the logs you can see gst_audio_converter_new warning about "unpositioned channels" and returning NULL.

Except then the audiomixer just continues with the unconverted data instead of failing.

Interesting, what would you expect to happen here? Should audiomixer make up a channel-mask or error out? Also audiotestsrc should probably output a channel-mask but that's a separate question :)

There are default channel masks we use if none is specified (for <= 8 channels), so that shouldn't be the problem, should it?

I have a patch (almost ready) that makes it return NOT-NEGOTIATED if the conversion is invalid (it's a FIXME in audioaggregator), but this is interesting, can you give me a pointer to said default channel masks?

https://gstreamer.freedesktop.org/documentation/audio/gstaudiochannels.html?gi-language=c#gst_audio_channel_get_fallback_mask

Yes, that's what I was thinking of, but I assumed audio_converter didn't call on that, or why would it complain about unpositioned channels in the first place?

If it doesn't... shouldn't it? :)

You tell me, I don't really have an opinion :)

Unless anyone else has an objection, I'll make it use the default channel mask :)

It's fine to use the default mask and still complain in the debug log imho. It usually means something upstream should've handled this in one way or another.

I agree, but if it can't figure out a channel layout (i.e. too many channels) then it should still fail negotiation instead of producing random noise.