static int mov_read_dvc1(MOVContext *c, AVIOContext *pb, MOVAtom atom)
{
    AVStream *st;
    uint8_t profile_level;

    if (c->fc->nb_streams < 1)
        return 0;
    st = c->fc->streams[c->fc->nb_streams-1];

    if (atom.size >= (1<<28) || atom.size < 7)
        return AVERROR_INVALIDDATA;

    profile_level = avio_r8(pb);
    if (profile_level & 0xf0 != 0xc0)
        return 0;

    av_free(st->codec->extradata);
    st->codec->extradata_size = 0;
    st->codec->extradata = av_mallocz(atom.size - 7 + FF_INPUT_BUFFER_PADDING_SIZE);
    if (!st->codec->extradata)
        return AVERROR(ENOMEM);
    st->codec->extradata_size = atom.size - 7;
    avio_seek(pb, 6, SEEK_CUR);
    avio_read(pb, st->codec->extradata, st->codec->extradata_size);
    return 0;
}
static int mov_read_dvc1(MOVContext *c, AVIOContext *pb, MOVAtom atom)
{
    AVStream *st;
    uint8_t profile_level;

    if (c->fc->nb_streams < 1)
        return 0;
    st = c->fc->streams[c->fc->nb_streams-1];

    if (atom.size >= (1<<28) || atom.size < 7)
        return AVERROR_INVALIDDATA;

    profile_level = avio_r8(pb);
    if (profile_level & 0xf0 != 0xc0)
        return 0;

    av_free(st->codec->extradata);
    st->codec->extradata_size = 0;
    st->codec->extradata = av_mallocz(atom.size - 7 + FF_INPUT_BUFFER_PADDING_SIZE);
    if (!st->codec->extradata)
        return AVERROR(ENOMEM);
    st->codec->extradata_size = atom.size - 7;
    avio_seek(pb, 6, SEEK_CUR);
    avio_read(pb, st->codec->extradata, st->codec->extradata_size);
    return 0;
}