Quoting http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=443772: A WAV file matches audio/x-wav but also video/x-msvideo (both are defined at priority 50 in /usr/share/mime/magic). If I use xdgmime (cvs version) to detect mimetypes *only* with magic numbers (without globs), I get no mimetype at all because the lookup function in xdgmimemagic.c detects multiple mime types with same priority and can't make a decision (the result is discarded: see xdgmimemagic.c:685) I suppose that tools based on xdgmime (gnome-vfs for example) suffer the same problem but I didn't checked. I solved the pb easily by adjusting video/x-msvideo magic priority to 49 in /usr/share/mime/packages/freedesktop.org.xml and running update-mime-database. Perhaps another way to workaround the pb is to make video/x-msvideo match "RIFF" *AND* "AVI" (instead of "RIFF" or "AVI" as stated in xml file line 15516) Finally, even if I found a workaround or two, I don't know if it's an upstream bug or not. Both the magic file and the source code to use it are involved. The specification doesn't give a detailed magic matching algorithm...
The problem is, that both wav and msvideo (aka avi) have "RIFF" at byte 0. They only differ afterwards, i.e. have "WAVE" at byte 8 for wav and "AVI" at byte 8 for msvideo. Same applies to audio/x-riff as it also has "RIFF" in the magic list.
I couldn't reproduce the bug before, but I made the changes to require both the RIFF and AVI bits for AVI files. * freedesktop.org.xml.in: Require AVI files to have both the RIFF and the "AVI " bits, not just one of them (Closes: #12541) * tests/list: * tests/test.avi: * tests/test.wav: Add WAVE and AVI test files
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