MP3 file header and footer information

Im doing some research into the file header and footer information that describes an MP3 file.

Unfortuanlty, from what I've found to date, there appears to be no MP3 header, but only an MP3 frame header which describes the music in the frame.

Anyone got any experience of disassembling MP3 files?

MP3 is a frame-based, rather than file-based format. It doesn't define a file header or footer. What you're probably looking for is documentation for the ID3 tags, which are the de facto standard for adding metadata to MP3 files.

More information is available at http://www.id3.org/

There are probably any number of projects on SourceForge for reading and writing ID3 tags.

The mp3tool program I wrote is available from the Hijack site (link at top of this page). It is a rather simple program that parses the various frames and ID3 footer, and optionally makes some (limited) changes. It also does not use/depend upon a mass of third party libraries, which may make it easier to understand than some others.

Cheers

Anyone got any experience of disassembling MP3 files?

Yes. The MP3 frame header specification is described nicely on this page.

The reason there is no single "unified" header on an MP3 file is that it was meant to be capable of working as a streaming protocol that didn't require you to see the beginning or end of the stream.

As well as ID3v1 and ID3v2 you might want to parse this stuff: http://gabriel.mp3-tech.org/mp3infotag.html -- which works around some of the misfeaturage in the MP3 format itself, and does let you identify truncated or corrupted files if they were encoded with Lame.

Peter

Many thanks for those reply's time to do some digging.

I'm studying for my Computer Forensics certification, and ironicaly the practical is on illegal distribution of MP3's

Mark,

That tool rocks, I think it very nearly exactly what I need - I might have to do some hacking about for file offsets so I can identify where in my image the file is in relation to the disk blocks, but many many thanks.

I'll give you a well deserved entry in the assignment.