MJ2 (also known as Motion JPEG2000) is a video format defined by Part 3 of the JPEG 2000 standard. Note that the final standards are not freely available, but the committee drafts are. MJ2 supports audio as well.
According to the specification MJ2 is one of several specifications with common formatting, including JPEG2000, MPEG-4, and Quicktime, sharing a common definition for the structure of a file (a sequence of objects, called boxes for JPEG2000 and atoms for MP4 and QuickTime), and a common definition of the general structure of an object. Codestreams in Motion JPEG2000 files are JP2 codestreams, as defined for JPEG2000.
See also Wikipedia:JPEG 2000.
- Motion JPEG 2000 (committee draft).