static int ivr_read_header(AVFormatContext *s)

{

    unsigned tag, type, len, tlen, value;

    int i, j, n, count, nb_streams, ret;

    uint8_t key[256], val[256];

    AVIOContext *pb = s->pb;

    AVStream *st;

    int64_t pos, offset, temp;



    pos = avio_tell(pb);

    tag = avio_rl32(pb);

    if (tag == MKTAG('.','R','1','M')) {

        if (avio_rb16(pb) != 1)

            return AVERROR_INVALIDDATA;

        if (avio_r8(pb) != 1)

            return AVERROR_INVALIDDATA;

        len = avio_rb32(pb);

        avio_skip(pb, len);

        avio_skip(pb, 5);

        temp = avio_rb64(pb);

        while (!avio_feof(pb) && temp) {

            offset = temp;

            temp = avio_rb64(pb);

        }

        avio_skip(pb, offset - avio_tell(pb));

        if (avio_r8(pb) != 1)

            return AVERROR_INVALIDDATA;

        len = avio_rb32(pb);

        avio_skip(pb, len);

        if (avio_r8(pb) != 2)

            return AVERROR_INVALIDDATA;

        avio_skip(pb, 16);

        pos = avio_tell(pb);

        tag = avio_rl32(pb);

    }



    if (tag != MKTAG('.','R','E','C'))

        return AVERROR_INVALIDDATA;



    if (avio_r8(pb) != 0)

        return AVERROR_INVALIDDATA;

    count = avio_rb32(pb);

    for (i = 0; i < count; i++) {

        if (avio_feof(pb))

            return AVERROR_INVALIDDATA;



        type = avio_r8(pb);

        tlen = avio_rb32(pb);

        avio_get_str(pb, tlen, key, sizeof(key));

        len = avio_rb32(pb);

        if (type == 5) {

            avio_get_str(pb, len, val, sizeof(val));

            av_log(s, AV_LOG_DEBUG, "%s = '%s'\n", key, val);

        } else if (type == 4) {

            av_log(s, AV_LOG_DEBUG, "%s = '0x", key);

            for (j = 0; j < len; j++)

                av_log(s, AV_LOG_DEBUG, "%X", avio_r8(pb));

            av_log(s, AV_LOG_DEBUG, "'\n");

        } else if (len == 4 && type == 3 && !strncmp(key, "StreamCount", tlen)) {

            nb_streams = value = avio_rb32(pb);

        } else if (len == 4 && type == 3) {

            value = avio_rb32(pb);

            av_log(s, AV_LOG_DEBUG, "%s = %d\n", key, value);

        } else {

            av_log(s, AV_LOG_DEBUG, "Skipping unsupported key: %s\n", key);

            avio_skip(pb, len);

        }

    }



    for (n = 0; n < nb_streams; n++) {

        st = avformat_new_stream(s, NULL);

        if (!st)

            return AVERROR(ENOMEM);

        st->priv_data = ff_rm_alloc_rmstream();

        if (!st->priv_data)

            return AVERROR(ENOMEM);



        if (avio_r8(pb) != 1)

            return AVERROR_INVALIDDATA;



        count = avio_rb32(pb);

        for (i = 0; i < count; i++) {

            if (avio_feof(pb))

                return AVERROR_INVALIDDATA;



            type = avio_r8(pb);

            tlen  = avio_rb32(pb);

            avio_get_str(pb, tlen, key, sizeof(key));

            len  = avio_rb32(pb);

            if (type == 5) {

                avio_get_str(pb, len, val, sizeof(val));

                av_log(s, AV_LOG_DEBUG, "%s = '%s'\n", key, val);

            } else if (type == 4 && !strncmp(key, "OpaqueData", tlen)) {

                ret = ffio_ensure_seekback(pb, 4);

                if (ret < 0)

                    return ret;

                if (avio_rb32(pb) == MKBETAG('M', 'L', 'T', 'I')) {

                    ret = rm_read_multi(s, pb, st, NULL);

                } else {

                    avio_seek(pb, -4, SEEK_CUR);

                    ret = ff_rm_read_mdpr_codecdata(s, pb, st, st->priv_data, len, NULL);

                }



                if (ret < 0)

                    return ret;

            } else if (type == 4) {

                int j;



                av_log(s, AV_LOG_DEBUG, "%s = '0x", key);

                for (j = 0; j < len; j++)

                    av_log(s, AV_LOG_DEBUG, "%X", avio_r8(pb));

                av_log(s, AV_LOG_DEBUG, "'\n");

            } else if (len == 4 && type == 3 && !strncmp(key, "Duration", tlen)) {

                st->duration = avio_rb32(pb);

            } else if (len == 4 && type == 3) {

                value = avio_rb32(pb);

                av_log(s, AV_LOG_DEBUG, "%s = %d\n", key, value);

            } else {

                av_log(s, AV_LOG_DEBUG, "Skipping unsupported key: %s\n", key);

                avio_skip(pb, len);

            }

        }

    }



    if (avio_r8(pb) != 6)

        return AVERROR_INVALIDDATA;

    avio_skip(pb, 12);

    avio_skip(pb, avio_rb64(pb) + pos - avio_tell(s->pb));

    if (avio_r8(pb) != 8)

        return AVERROR_INVALIDDATA;

    avio_skip(pb, 8);



    return 0;

}
