Limits for user defined metadata in AVI files

[Yandot]

Hi guys,

I must code an app to put user defined metadata in AVI files.
Those metadata are binary, not text, and quite big (the ultimate size is not well defined).
I spent some time googling about but at the end I haven't clear if it is actually allowed to add this kind of metadata without breaking the AVI standard.

Does anybody know if it is possible and if there is a limit in size to those metadata?

Thanks

[jagabo]

Data in AVI files appears in "chunks". A chunk starts with a fourcc code identifying what that chunk is. That is followed by a four byte size (the size of the chunk, up to 4 GB, though in practice you should stick with less than 2 GB because some software uses signed inters rather than unsigned integers), then the the actual data of that chunk. So you can define your own fourcc and put whatever you want in that chunk. That will work fine with your own software since you will know how to deal with it. Other software will will just skip over it and proceed to the next chunk. If you want your metadata to be usable by other programs you'll need to stick with defined standards.

[Cornucopia]

A good place to stick something like this might be the "Junk"chunk. Most other apps would ignore it and there is no clear defined format for its contents.Know, however, that some other apps may want to stick their own junk in there (probably overwriting yours).

Scott