Fix issue where ForwardingAudioOutputProvider wasn't forwarding audio capabilities

[nift4]

No description provided.

[tonihei]

This isn't as straight-forward as you make it look like I'm afraid. The AudioOutputProvider has methods to check the format support internally based on its knowledge of the output path. The AudioCapabilties class is tighly coupled to the default AudioTrack output path and can't be easily moved to the stable API surface. That's the reason it's only available on the AudioTrackAudioOutputProvider. In fact, the method was only added there as a slightly hacky workaround to retrieve the available spatialization channel masks to configure IAMF output in the codec, and it has no other purpose. Given that, we'd need to find a more generic solution for the IAMF config problem instead of simply publishing the AudioCapabilities via the interface.

[nift4]

Thanks for the explaination, I see. So it's only a short term solution, that makes sense.

[nift4]

Are you interested in a PR taking a shot at a more generic API to query suggested spatialization, or is the problem it not being spec'd out yet?

[tonihei]

We haven't thought this through yet to see what the best design would be exactly to be honest. If you have a suggestion for something that fits nicely into the interface, feel free to suggest it for discussion.