static int wc3_read_packet(AVFormatContext *s,
                           AVPacket *pkt)
{
    Wc3DemuxContext *wc3 = s->priv_data;
    ByteIOContext *pb = s->pb;
    unsigned int fourcc_tag;
    unsigned int size;
    int packet_read = 0;
    int ret = 0;
    unsigned char text[1024];
    unsigned int palette_number;
    int i;
    unsigned char r, g, b;
    int base_palette_index;

    while (!packet_read) {

        fourcc_tag = get_le32(pb);
        /* chunk sizes are 16-bit aligned */
        size = (get_be32(pb) + 1) & (~1);
        if (url_feof(pb))
            return AVERROR(EIO);

        switch (fourcc_tag) {

        case BRCH_TAG:
            /* no-op */
            break;

        case SHOT_TAG:
            /* load up new palette */
            palette_number = get_le32(pb);
            if (palette_number >= wc3->palette_count)
                return AVERROR_INVALIDDATA;
            base_palette_index = palette_number * PALETTE_COUNT * 3;
            for (i = 0; i < PALETTE_COUNT; i++) {
                r = wc3->palettes[base_palette_index + i * 3 + 0];
                g = wc3->palettes[base_palette_index + i * 3 + 1];
                b = wc3->palettes[base_palette_index + i * 3 + 2];
                wc3->palette_control.palette[i] = (r << 16) | (g << 8) | (b);
            }
            wc3->palette_control.palette_changed = 1;
            break;

        case VGA__TAG:
            /* send out video chunk */
            ret= av_get_packet(pb, pkt, size);
            pkt->stream_index = wc3->video_stream_index;
            pkt->pts = wc3->pts;
            packet_read = 1;
            break;

        case TEXT_TAG:
            /* subtitle chunk */
#if 0
            url_fseek(pb, size, SEEK_CUR);
#else
            if ((unsigned)size > sizeof(text) || (ret = get_buffer(pb, text, size)) != size)
                ret = AVERROR(EIO);
            else {
                int i = 0;
                av_log (s, AV_LOG_DEBUG, "Subtitle time!\n");
                av_log (s, AV_LOG_DEBUG, "  inglish: %s\n", &text[i + 1]);
                i += text[i] + 1;
                av_log (s, AV_LOG_DEBUG, "  doytsch: %s\n", &text[i + 1]);
                i += text[i] + 1;
                av_log (s, AV_LOG_DEBUG, "  fronsay: %s\n", &text[i + 1]);
            }
#endif
            break;

        case AUDI_TAG:
            /* send out audio chunk */
            ret= av_get_packet(pb, pkt, size);
            pkt->stream_index = wc3->audio_stream_index;
            pkt->pts = wc3->pts;

            /* time to advance pts */
            wc3->pts++;

            packet_read = 1;
            break;

        default:
            av_log (s, AV_LOG_ERROR, "  unrecognized WC3 chunk: %c%c%c%c (0x%02X%02X%02X%02X)\n",
                (uint8_t)fourcc_tag, (uint8_t)(fourcc_tag >> 8), (uint8_t)(fourcc_tag >> 16), (uint8_t)(fourcc_tag >> 24),
                (uint8_t)fourcc_tag, (uint8_t)(fourcc_tag >> 8), (uint8_t)(fourcc_tag >> 16), (uint8_t)(fourcc_tag >> 24));
            ret = AVERROR_INVALIDDATA;
            packet_read = 1;
            break;
        }
    }

    return ret;
}