gf_isom_set_alternate_group_id 667 applications/mp4box/fileimport.c gf_isom_set_alternate_group_id(import.dest, i+1, group); gf_isom_set_alternate_group_id 789 applications/mp4box/fileimport.c gf_isom_set_alternate_group_id(import.dest, track, group); gf_isom_set_alternate_group_id 1098 include/gpac/isomedia.h GF_Err gf_isom_set_alternate_group_id(GF_ISOFile *movie, u32 trackNumber, u32 groupId);