Function jpeg_parse_packet

libavformat/rtpdec_jpeg.c:214–388

}

static int jpeg_parse_packet(AVFormatContext *ctx, PayloadContext *jpeg,
                             AVStream *st, AVPacket *pkt, uint32_t *timestamp,
                             const uint8_t *buf, int len, uint16_t seq,
                             int flags)
{
    uint8_t type, q, width, height;
    const uint8_t *qtables = NULL;
    uint16_t qtable_len;
    uint32_t off;
    int ret, dri = 0;

    if (len < 8) {
        av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
        return AVERROR_INVALIDDATA;
    }

    /* Parse the main JPEG header. */
    off    = AV_RB24(buf + 1);  /* fragment byte offset */
    type   = AV_RB8(buf + 4);   /* id of jpeg decoder params */
    q      = AV_RB8(buf + 5);   /* quantization factor (or table id) */
    width  = AV_RB8(buf + 6);   /* frame width in 8 pixel blocks */
    height = AV_RB8(buf + 7);   /* frame height in 8 pixel blocks */
    st->codecpar->width = width*8;
    st->codecpar->height = height*8;
    buf += 8;
    len -= 8;

    if (type & 0x40) {
        if (len < 4) {
            av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
            return AVERROR_INVALIDDATA;
        }
        dri = AV_RB16(buf);
        buf += 4;
        len -= 4;
        type &= ~0x40;
    }
    if (type > 1) {
        avpriv_report_missing_feature(ctx, "RTP/JPEG type %"PRIu8, type);
        return AVERROR_PATCHWELCOME;
    }

    /* Parse the quantization table header. */
    if (off == 0) {
        /* Start of JPEG data packet. */
        uint8_t new_qtables[128];
        uint8_t hdr[1024];

        if (q > 127) {
            uint8_t precision;
            if (len < 4) {
                av_log(ctx, AV_LOG_ERROR, "Too short RTP/JPEG packet.\n");
                return AVERROR_INVALIDDATA;
            }

            /* The first byte is reserved for future use. */
            precision  = AV_RB8(buf + 1);    /* size of coefficients */
            qtable_len = AV_RB16(buf + 2);   /* length in bytes */