Skip to main content ↑ ↓

Notice

Please note that most of the software linked on this forum is likely to be safe to use. If you are unsure, feel free to ask in the relevant topics, or send a private message to an administrator or moderator. To help curb the problems of false positives, or in the event that you do find actual malware, you can contribute through the article linked here.
Topic: MP4/M4A Metadata Specification (Read 9662 times) previous topic - next topic
0 Members and 1 Guest are viewing this topic.

MP4/M4A Metadata Specification

I'm currently writing an application (Delphi) which is able to produce an iPod compatible audiobook (one AAC/M4B file) from a M3U playlist of MP3 files. I use "neroAacEnc.exe" as a command line converter tool.
After using "neroAacTag.exe" for some time now to apply the metadata/cover art I'd like to write my own MP4 tagging library but I really cannot find some specs about the structure of tag format uses in those files.

Any help/link/tip is highly appreciated...

MP4/M4A Metadata Specification

Reply #2 –
I threw together some M4A notes in my audio formats reference (page 67) which you might find useful.  Important things to remember are that if you adjust the size of the 'moov' atom and force 'mdat' to move (almost certain if adding cover art), you must adjust the offsets in the 'stco' atom or the file may be unplayable.  And, try not to muck around with the '----' atoms inside of 'meta' if you can avoid it.

MP4/M4A Metadata Specification

Reply #3 –
tuffy & 2E7AH,

thanks a lot for your valuable input - lots of interessting stuff to read.
Although iTunes/iPod is in the wild for quite a while now, information about internal details are sometimes hard to find (e.g. ITUNSMPB fields and SoundCheck).

.sundance.