I think you're overreacting. Since one must use the Ogg library to play the files anyway, it is entirely reasonable to ask the Ogg library whether it is capable of playing the file, rather than shelling out to some external program that might or might not make the same decisions.
The suggestion to use file(1) instead was predicated on ov_open somehow cozying up to stdio and making it break, an accusation that has turned out to be false. In reality ov_open is perfectly well documented (http://www.xiph.org/vorbis/doc/vorbisfile/ov_open.html) and does exactly what is called for without any extra work. Just use that. Also, the MIME type should be application/x-ogg unless ogg has actually been registered with the MIME people. Russ
