Would it be possible to add support for WebM files that use the Opus codec? I’m working on a project which is obtaining the audio from the browser via WebRTC and it seems WebM with Opus is the most widely supported format.

None of the formats the API currently supports – WAV, MP3, M4a or Ogg – appear to be supported by browsers for WebRTC. Firefox supports Ogg but with the Opus codec whereas the API appears to support Ogg with the Vorbis codec.