Creating looping audio files by godzfire at 12:50 PM EST on March 1, 2015
So, if what I read is correct, XA audio unfortunately isn't loopable, even though I swear in the past I was able to play MegaMan X5's music on loop in WinAmp somehow.
Does anyone know how to create loops in MP3s where it bypasses the intro of the song the second time around?
MP3 doesn't support loop points (though I'm sure you already know this), and it has yet to be found "in the wild". However, there are numerous implementations for looping OGG files, so I'd suggest that route. VGMstream supports all of the looping OGG (*.LOGG) variants I've seen, and even supports making your own (check the readme.txt, or simply run "test.exe" with no parameters in the command prompt). You will need to download the command-line ogg encoder (google search, I think I'm using the top result from RareWares, renamed to match VGMstream's expectations), and probably make a batch file, to do it though.
Technically, there are numerous looping MP3s out there, but none of them use a standard MP3 header. VGMTb has been used to create GENH files containing MP3 data, and using the GENeral Header, added loop points. I think MSF (found in some Atelier games? I think?) has also contained MP3 data inside a custom header with loop points. So you *can* create looping MP3s, but it's easier to create LOGG files. Not only do LOGGs support looping, but they hold to the standard OGG specifications, and can therefore be played by a regular music player (that supports OGG playback) albeit without loops (just remove the "L" from the extension).
Years ago, I converted the Tetrisphere USF set to both LOGG and ADX, using VGMstream (on second thought, I can't recall if I used VGMstream or not. Considering that USF is xSF/PSF format, I'm not sure how VGMstream would have been useful in that situation. I probably used Winamp's WAV writer to do the decoding), Audacity, adxencd and oggenc. So I know it's doable. Good luck! Hopefully this has been helpful. Mouser X over and out.