Rather low priority issue, since nobody seems to use dirac, but probably wouldn't hurt to support it. Googling suggests its one of the few free formats that have a lossless option, which perhaps might make it useful for something (Maybe? I don't really know). Basically I was bored today, tried to upload a test file to see if dirac would work, low and behold it didn't, so thought I'd file a bug.
Probably most of what has to be done is to update File_OGG to recognize dirac streams.
See also: https://commons.wikimedia.org/wiki/File:Minnehaha_Falls_on_June_22,_2013_-_Video_1_of_4.ogv
Version: unspecified
Severity: enhancement