static int mov_check_bitstream(struct AVFormatContext *s, const AVPacket *pkt)
{
    int ret = 1;
    AVStream *st = s->streams[pkt->stream_index];

    if (st->codecpar->codec_id == AV_CODEC_ID_AAC) {
        if (pkt->size > 2 && (AV_RB16(pkt->data) & 0xfff0) == 0xfff0)
            ret = ff_stream_add_bitstream_filter(st, "aac_adtstoasc", NULL);
    }

    return ret;
}
Unknown