MATROSKA_ID_VIDEOALPHAMODE  356 libavformat/matroskadec.c     { MATROSKA_ID_VIDEOALPHAMODE,      EBML_UINT,  0, offsetof(MatroskaTrackVideo, alpha_mode) },
MATROSKA_ID_VIDEOALPHAMODE  961 libavformat/matroskaenc.c             put_ebml_uint(pb, MATROSKA_ID_VIDEOALPHAMODE, 1);