Splitting Mp3's

caseydk writes: "I'm working on a project that needs to take a single mp3 (a live recording) and play individual sections of it. Preferably, so that the user must only download a portion of the mp3, instead of the whole thing. Unfortunately, most (or all) mp3 splitters that I have found have a gui. I'm looking for something command-line, so that I can just have the server do it during low usage times or (worst case) on the fly. Any suggestions?"

Comments

headerless format

[Rebar]

Since MP3 is headerless, you should be able to just calculate where in the file you want to be based on the bitrate, and use 'dd' to cut out a snippet.

I've tried this and it sometimes works and sometimes doesn't depending on the player, since the start of your file snippet will have junk in it, but it seems to me that it would be an easy programming exercise to create a program that would lop off the leading junk until it finds the next valid MP3 frame.

I don't claim to know much about MP3 format, but it appears from a quick session with a hex editor that frames start with 0xfffb9200 - can anyone verify this? If so, you could hack out something in an hour that would be fast, scriptable and do exactly what you want.

For extra credit points, you could then use mp3info to add id3 tags so your file will look cool when playing in xmms or whatever.

I've done this...

[Brazilian Geek]

... using dd.

I know about the MP3 file header but before I knew about it I was chopping MP3s just for kicks. It works, it's easy and knowing the kbps of the file you can calculate the exact point to start and end. Example:

dd if=biggie_file.mp3 of=shortie_file.mp3 bs=1c seek=200k count=150k

It REALLY does work and it's command line - not to mention all the piping possibilites.