[smalltorch]

Yes it's encoding in opus, and optionally you can configure encoding quality from 6kbs to 64kbs.

I was really surprised at the intelligability even at 6kbs.

The caviot is if your on termux we have to use the seperate termux API application to pipe audio to termux, and ffmpeg to convert MP4 to opus. Unfortunately termux cannot activate the mic on its own.

[encom]

By MP4 I assume you mean AAC in MP4. I'm a bit confused by this. What emits AAC that then needs transcoding to Opus? Not that transcoding losses really matter for this application, but the pipeline is not clear to me?

Very interesting project, by the way.

[smalltorch]

So this is only for termux compatibility. On a standard distro it skips this step entirely and goes straight from raw pcm to opus.

On termux 'termux-microphone-record' is a wrapper around androids 'mediarecorder'. It doesn't support raw pcm output. It records AAC in m4a wrapper and then the extra ffmpeg package converts this to rawpcm so it can follow the same pipeline.