static short[] decodeAudioFileToStereoSamples(File file) {
  if (file == null) null;
  if (isMP3File(file))
    ret decodeWAVToStereoSamples(mp3ToTempWAV(file));
  else if (isWAVFile(file))
    ret decodeWAVToStereoSamples(file);
  fail("Unknown audio type: " + file);
}