static int cdxl_read_packet(AVFormatContext *s, AVPacket *pkt)
{
    CDXLDemuxContext *cdxl = s->priv_data;
    AVIOContext *pb = s->pb;
    uint32_t current_size, video_size, image_size;
    uint16_t audio_size, palette_size, width, height;
    int64_t  pos;
    int      format, frames, ret;

    if (avio_feof(pb))
        return AVERROR_EOF;

    pos = avio_tell(pb);
    if (!cdxl->read_chunk &&
        avio_read(pb, cdxl->header, CDXL_HEADER_SIZE) != CDXL_HEADER_SIZE)
        return AVERROR_EOF;
    if (cdxl->header[0] != 1) {
        av_log(s, AV_LOG_ERROR, "non-standard cdxl file\n");
        return AVERROR_INVALIDDATA;
    }

    format       = cdxl->header[1] & 0xE0;
    current_size = AV_RB32(&cdxl->header[2]);
    width        = AV_RB16(&cdxl->header[14]);
    height       = AV_RB16(&cdxl->header[16]);
    palette_size = AV_RB16(&cdxl->header[20]);
    audio_size   = AV_RB16(&cdxl->header[22]);
    if (FFALIGN(width, 16) * (uint64_t)height * cdxl->header[19] > INT_MAX)
        return AVERROR_INVALIDDATA;
    if (format == 0x20)
        image_size = width * height * cdxl->header[19] / 8;
    else
        image_size = FFALIGN(width, 16) * height * cdxl->header[19] / 8;
    video_size   = palette_size + image_size;

    if (palette_size > 512)
        return AVERROR_INVALIDDATA;
    if (current_size < (uint64_t)audio_size + video_size + CDXL_HEADER_SIZE)
        return AVERROR_INVALIDDATA;

    if (cdxl->read_chunk && audio_size) {
        if (cdxl->audio_stream_index == -1) {
            AVStream *st = avformat_new_stream(s, NULL);
            if (!st)
                return AVERROR(ENOMEM);

            st->codecpar->codec_type    = AVMEDIA_TYPE_AUDIO;
            st->codecpar->codec_tag     = 0;
            st->codecpar->codec_id      = AV_CODEC_ID_PCM_S8;
            if (cdxl->header[1] & 0x10) {
                st->codecpar->channels       = 2;
                st->codecpar->channel_layout = AV_CH_LAYOUT_STEREO;
            } else {
                st->codecpar->channels       = 1;
                st->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
            }
            st->codecpar->sample_rate   = cdxl->sample_rate;
            st->start_time           = 0;
            cdxl->audio_stream_index = st->index;
            avpriv_set_pts_info(st, 64, 1, cdxl->sample_rate);
        }

        ret = av_get_packet(pb, pkt, audio_size);
        if (ret < 0)
            return ret;
        pkt->stream_index = cdxl->audio_stream_index;
        pkt->pos          = pos;
        pkt->duration     = audio_size;
        cdxl->read_chunk  = 0;
    } else {
        if (cdxl->video_stream_index == -1) {
            AVStream *st = avformat_new_stream(s, NULL);
            if (!st)
                return AVERROR(ENOMEM);

            st->codecpar->codec_type    = AVMEDIA_TYPE_VIDEO;
            st->codecpar->codec_tag     = 0;
            st->codecpar->codec_id      = AV_CODEC_ID_CDXL;
            st->codecpar->width         = width;
            st->codecpar->height        = height;

            if (audio_size + video_size && cdxl->filesize > 0) {
                frames = cdxl->filesize / (audio_size + video_size);

                if(cdxl->framerate)
                    st->duration = frames;
                else
                    st->duration = frames * (int64_t)audio_size;
            }
            st->start_time           = 0;
            cdxl->video_stream_index = st->index;
            if (cdxl->framerate)
                avpriv_set_pts_info(st, 64, cdxl->fps.den, cdxl->fps.num);
            else
                avpriv_set_pts_info(st, 64, 1, cdxl->sample_rate);
        }

        if (av_new_packet(pkt, video_size + CDXL_HEADER_SIZE) < 0)
            return AVERROR(ENOMEM);
        memcpy(pkt->data, cdxl->header, CDXL_HEADER_SIZE);
        ret = avio_read(pb, pkt->data + CDXL_HEADER_SIZE, video_size);
        if (ret < 0) {
            av_packet_unref(pkt);
            return ret;
        }
        av_shrink_packet(pkt, CDXL_HEADER_SIZE + ret);
        pkt->stream_index  = cdxl->video_stream_index;
        pkt->flags        |= AV_PKT_FLAG_KEY;
        pkt->pos           = pos;
        pkt->duration      = cdxl->framerate ? 1 : audio_size ? audio_size : 220;
        cdxl->read_chunk   = audio_size;
    }

    if (!cdxl->read_chunk)
        avio_skip(pb, current_size - audio_size - video_size - CDXL_HEADER_SIZE);
    return ret;
}