static int check(AVIOContext *pb, int64_t pos) { int64_t ret = avio_seek(pb, pos, SEEK_SET); unsigned header; MPADecodeHeader sd; if (ret < 0) return ret; header = avio_rb32(pb); if (ff_mpa_check_header(header) < 0) return -1; if (avpriv_mpegaudio_decode_header(&sd, header) == 1) return -1; return sd.frame_size; }