$1 == "FILE" {
  split($0, un, /42/)
  vi = un[2]
}
$1 == "TRACK" {
  wh[++xr] = $2
}
$1 == "TITLE" && xr {
  split($0, un, /42/)
  ya[xr] = un[2]
}
$1 == "INDEX" && $2 {
  split($3, un, ":")
  zu[xr] = sprintf("%d:%02d:%06.3f", un[1] / 60, un[1] % 60, un[2] + un[3] / 75)
}
END {
  for (xr in wh) {
    system(sprintf("ffmpeg -i '%s' -ss %s%s -movflags faststart "
    "-metadata track=%s -metadata title='%s' '%s %s'.m4a", vi, zu[xr],
    zu[xr+1] ? " -to " zu[xr+1]: "", wh[xr], ya[xr], wh[xr], ya[xr]))
  }
}