For software I'm working on, I need to store information in an mp4 file that is not available in the tag editors I have found so far, and so I assume that there is no registered atom available for this.
The only document that I have found so far that explains MP4 tagging is from Atomic Parsley (http://atomicparsley.sourceforge.net/mpeg-4files.html).
It looks like there might be 3 options to add the data I want to add:
1. Make up atom names myself
According to that document, this isn't allowed, and I can understand why it isn't really wanted
"A generic tool isn't allowed to create their own atoms"
2. Make use of an uuid atom
If I understand it correctly, this is very similar to making up an atom name yourself, but with 'uuid' added in front of it?
Or is it not just a name, but an actual unique identifier that you generate and then use for just your own application?
Since I just noticed Atomic Parley supports using it, I guess I could try how it works.
3. According to this document (http://www.mp4ra.org/specs.html#id3v2) it is possible to embed id3v2 tags inside an mp4 file
The advantage is that there are quite a lot of fields already defined for id3 tags, and it has support for adding custom fields if required as well.
My application also uses id3 tags for mp3 files already anyway, so that would also make it easier to use this method.
The problem is that I haven't found any software that does this already, and I don't completely understand the exact data structure required to add them, so I'd rather not implement this the wrong way risking making files corrupt or incompatible with other software.
So my question is if anyone here knows more about this, or maybe some software that already supports it.
The fields I'm currently trying to add are cue points and stored loops btw, but I might need other fields as well in the future.
It isn't easy to figure out...but I found I could fix almost any customized field I needed using MP3tag. I can also embed album art, customized atom fields, and embed everything into an .m4a file. Sometimes the embedded atoms were difficult to view in iTunes....same thing in Windows Media Player, Foobar2000. These are the only players I tried, and didn't spend a lot of time mapping fields to appear. If you are still interested in this, let me know, and I will try to help.