music_sdl: left/right channels swapped when some .ogg files loop

[rversteegen]

When certain 2 channel .ogg files are played by music_sdl the left & right channels swap every time it loops, swapping back the right way after two plays. Seen on both Windows (SDL_mixer.dll v1.2.12) and Linux (SDL_mixer 1.2.12, libogg 1.3.4).

The swapping doesn't happen if the ogg is converted to wav (played in the file browser), but converting that back again to ogg makes it swap again. Trimming the wav short using dd stop the swapping either.

I don't suggest doing anything about it, just filing for reference.

The title music (song 0) to Prifurin's Moonday is one song affected, and I'm attaching another (Mmrnmhrm ditty by Jouni Airaksinen, The Ur-Quan Masters remix): mmrditty.zip

[rversteegen]

In case it's not obvious, it doesn't happen in SDL_mixer 2, however there's no mention of it in the changelog, hg log, SDL bugzilla or the web.