Function parse_packed_headers

libavformat/rtpdec_xiph.c:224–284

* Based off parse_packed_headers in Vorbis RTP */

 * Based off parse_packed_headers in Vorbis RTP
 */
static int
parse_packed_headers(AVFormatContext *s,
                     const uint8_t * packed_headers,
                     const uint8_t * packed_headers_end,
                     AVCodecParameters *par, PayloadContext * xiph_data)
{

    unsigned num_packed, num_headers, length, length1, length2, extradata_alloc;
    int ret;
    uint8_t *ptr;

    if (packed_headers_end - packed_headers < 9) {
        av_log(s, AV_LOG_ERROR,
               "Invalid %td byte packed header.",
               packed_headers_end - packed_headers);
        return AVERROR_INVALIDDATA;
    }

    num_packed         = bytestream_get_be32(&packed_headers);
    xiph_data->ident   = bytestream_get_be24(&packed_headers);
    length             = bytestream_get_be16(&packed_headers);
    num_headers        = get_base128(&packed_headers, packed_headers_end);
    length1            = get_base128(&packed_headers, packed_headers_end);
    length2            = get_base128(&packed_headers, packed_headers_end);

    if (num_packed != 1 || num_headers > 3) {
        avpriv_report_missing_feature(s, "%u packed headers, %u headers",
                                      num_packed, num_headers);
        return AVERROR_PATCHWELCOME;
    }

    if (packed_headers_end - packed_headers != length ||
        length1 > length || length2 > length - length1) {
        av_log(s, AV_LOG_ERROR,
               "Bad packed header lengths (%d,%d,%td,%u)\n", length1,
               length2, packed_headers_end - packed_headers, length);
        return AVERROR_INVALIDDATA;
    }

    /* allocate extra space:
     * -- length/255 +2 for xiphlacing
     * -- one for the '2' marker
     * -- AV_INPUT_BUFFER_PADDING_SIZE required */
    extradata_alloc = length + length/255 + 3 + AV_INPUT_BUFFER_PADDING_SIZE;

    if ((ret = ff_alloc_extradata(par, extradata_alloc)) < 0) {
        av_log(s, AV_LOG_ERROR, "Out of memory\n");
        return ret;
    }
    ptr = par->extradata;
    *ptr++ = 2;
    ptr += av_xiphlacing(ptr, length1);
    ptr += av_xiphlacing(ptr, length2);
    memcpy(ptr, packed_headers, length);
    ptr += length;
    par->extradata_size = ptr - par->extradata;
    // clear out remaining parts of the buffer
    memset(ptr, 0, extradata_alloc - par->extradata_size);