Hi, It appears Monkey Audio demuxer sets codec_tag to 'APE ' while official fourcc (which is looked for in probe()) is 'MAC '. > st->codec->codec_type = CODEC_TYPE_AUDIO; > st->codec->codec_id = CODEC_ID_APE; > st->codec->codec_tag = MKTAG('A', 'P', 'E', ' '); Kostya, any reason you did this ? Ben