What is the maximum size of JPEG metadata?

Question

Is there a theoretical maximum to the amount of metadata (EXIF, etc) that can be incorporated in a JPEG file? I\'d like to allocate a buffer that is assured to be sufficient

Answer 1

Each APPN data area has a length field that is 2 bytes, so 65536 would hold the biggest one. If you are just worried about the EXIF data, it would be a bit less.
http://www.fileformat.info/format/jpeg/egff.htm There are at most 16 different APPN markers in a single file. I don't think they can be repeated, so 16*65K should be the theoretical max.