avformat/libopenmpt: Probe file format from file data if possible
When building with libopenmpt 0.3, use the libopenmpt file header probing functions for probing. libopenmpt probing functions are allocation-free and designed to be as fast as possible. For libopenmpt 0.2, or when libopenmpt 0.3 file header probing cannot probe successfully due to too small probe buffer, test the filename against the file extensions supported by the libopenmpt library that is actually linked, instead of relying on a hard-coded file extension list. File extension testing is also allocation-free and designed to be fast in libopenmpt. Avoiding a hard-coded file extension list is useful because later libopenmpt versions will likely add support for more module file formats. libopenmpt file header probing is tested regularly against the FATE suite and other diverse file collections by libopenmpt upstream in order to avoid false positives. FATE passes with './configure --enable-libopenmpt' as well as with './configure --enable-libopenmpt --enable-libmodplug'. libopenmpt probing adds about 5%..10% cpu time (depending on precise usage pattern and host CPU and compiler version used for libopenmpt) compared to all current internal FFmpeg probing functions combined in tools/probetest for all of its module formats combined (currently 41 modules formats in libopenmpt 0.3.4 and 234 file formats in FFmpeg). Signed-off-by:Jörn Heusipp <osmanx@problemloesungsmaschine.de> Reviewed-by:
Josh de Kock <josh@itanimul.li> Signed-off-by:
Michael Niedermayer <michael@niedermayer.cc>
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