Are there other mp3 playback externals?
[else/play.file~] used to be an abstraction based on [readsf~] but since the last update (RC12) it is now a compiled object that supports MP3, FLAC, WAV, AIF, AAC, OGG & OPUS audio file extensions. A new [sfload] object can import these files into arrays (but still needs lots of more work). There are many other player objects in ELSE that can load and play samples but these don't yet support these new formats (hang in there for the next version update).
This is all thanks to Tim Schoen by the way, who is yet to port this and include it in PlugData itself.
cheers