The currently stable sys-apps/file (libmagic) which returns audio/mgep; charset=binary for .mp3 files (at least the ones I tested) which sox 14.2 doesn't handle correctly. Upgrading sox to 14.3 resolves the issue. My recommendation would be to stabilize sox-14.3.0. I've personally been using it for some time now and have not experienced any problems with it. The alternative solution is to back-port some patch, or to downgrade sys-apps/file. Reproducible: Always Steps to Reproduce:
arches: please mark 14.3.0 stable as explained above, the current stable is broken by file-5 stabilization.
amd64/x86 stable
ppc stable
Stable for HPPA.
Stable on alpha.
ppc64 done
sparc stable, closing