Saturday, October 10, 2009

Join MP3 files with a UNIX shell command

I have been listening to a lot of audio books lately, which I have typically imported from CDs onto my iPhone via iTunes. Most of the Icelandic audio CDs I have listened to are in MP3 format and described in the SMIL markup language, which iTunes has no concept of. The files are named 01.mp3, 02.mp3, ... and so on and are void of any ID3 information, with all the metadata in those .smil files. Anywho, to my frustration once imported into iTunes, neither iTunes nor my iPhone have the good sense of playing the files in the correct order. Why they play them in some arbitrary order other than by file name, I have no idea, and iTunes does not seem to have any way of changing the play order. So I figured I needed some way to join the files into a single MP3 file so iTunes/iPhone couldn't mess up the order. After googling around for products to join MP3 files and mainly finding shareware software that I wasn't willing to pay for, I stumbled up on the fact that since MP3 is a streaming format you can simply concatenate MP3 files using the good old Unix cat command! So I came up with the following one-liner to join the files together (in alphabetic order), which happily runs on my Mac:

find /Volumes/My\ Disc/*.mp3 -exec cat {} >> MyAudioBook.mp3 \;


Where "/Volumes/My\ Disc/" is the Mac CD drive, and MyAudioBook.mp3 is the final output file that can be imported into iTunes.
Anyways, I figured I'd share this one, as I have to admit I was surprised to learn that MP3 files could simply be "cat"ed together :-)

3 comments:

Dennis said...

Thanks for the tip. I have an iPod touch. I like Unix cat. Happy American Thanksgiving! - Dennis G at Affinion.

Paul Miller said...
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pleaseupdown said...

I just find a step by step guide for the Best MP3 Joiner at http://www.avdshare.com/join-mp3-files