revid/audio_linux.go: addition of MTS meta shouldn't happen here

[Saxon Milton]

Prerequisite to issue #186

The addition of MTS meta to describe the audio characteristics should ideally be done by the MTS encoder when it knows stuff about the audio/video format, or (less ideally) by revid, but not by the implementation of the input device. It’s suggested that for the time being revid handle this.

[Alan Noble]

I think it is reasonable to obtain certain AV-specific metadata, such frame rate, resolution, etc., from the AVDevice implementation (although not other metadata such as location). The AVDevice interface could expose a Get method that enables callers to query an implementation for such properties (which the MTS encoder could use).

[Saxon Milton]

yeah, I think that’s a nice idea. I just didn’t like that fact that the current implementation of the audio device had a dependency on the mts package to directly add the metadata.

[Alan Noble]

Agreed. Revid is the only component that should depend on device and mts packages. Their should be no inter-dependencies between the latter.

[Saxon Milton]

Resolve in PR #275