MATROSKA_ID_BLOCKGROUP  487 libavformat/matroskadec.c     { MATROSKA_ID_BLOCKGROUP,     EBML_NEST, sizeof(MatroskaBlock), offsetof(MatroskaCluster,blocks), {.n=matroska_blockgroup} },
MATROSKA_ID_BLOCKGROUP  750 libavformat/matroskaenc.c         blockgroup = start_ebml_master(pb, MATROSKA_ID_BLOCKGROUP, mkv_blockgroup_size(size));
MATROSKA_ID_BLOCKGROUP  823 libavformat/matroskaenc.c         ebml_master blockgroup = start_ebml_master(pb, MATROSKA_ID_BLOCKGROUP, mkv_blockgroup_size(pkt->size));