go-mp3 codecs

[wsc1]

Incorporate go-mp3.

[wsc1]

based on a small C mp3 library. So we can't incorporate it directly, but perhaps we can make an example people can refer to in case of need while we wait for Go implementations.

[wsc1]

Now I'm not sure what made me think it was based on a C mp3 library. README says pure Go, whatever I saw before didn't.

go.mod indicates a dependency on oto.

Licensing is Apache; would be nice to see if it's possible to arrive at a single collective license.

[mewmew]

go.mod indicates a dependency on oto.

Would be interesting to see if this dependency can be split out from the rest of the project, to only handle encoding/decoding.

[wsc1]

go.mod indicates a dependency on oto.

Would be interesting to see if this dependency can be split out from the rest of the project, to only handle encoding/decoding.

Yes, after this discussion, looks like we're going to try to put it in /ext.