static internal extern C_INT ov_test_callbacks(IntPtr datasource, [In, Out] ref OggVorbisFile vf, C_CHARPTR initial, C_LONG ibytes, OvCallbacks callbacks);
static internal extern C_INT ov_test_open([In, Out] ref OggVorbisFile vf);
static internal extern C_INT ov_test(C_FILEPTR f, [In, Out] ref OggVorbisFile vf, C_CHARPTR initial, C_LONG ibytes);