I’ve run into an issue with a little portable music player I have – it doesn’t make reasonable assumptions about the order in which to play the tracks of an audio book. Even when the files are named sequentially with numbers, when the timestamps are in the order they should be played back, when there are valid and correct track numbers in the ID3 tags, and regardless of the order in which they are copied to the device (corresponding to the order of their entries in the filesystem lookup table), they always play in what seems like random order (this doesn’t happen with music, which works as one would expect). I’ve found that the easiest solution to this is to just wrap them up into a single large MP3 that contains the whole book. There are many ways to accomplish this, and here I’ll show a tool called mp3wrap that worked simply and reliably for me.