static int sdp_parse_fmtp_config_h264(AVStream * stream,
                                      PayloadContext * h264_data,
                                      char *attr, char *value)
{
    AVCodecContext *codec = stream->codec;
    assert(codec->codec_id == CODEC_ID_H264);
    assert(h264_data != NULL);

    if (!strcmp(attr, "packetization-mode")) {
        av_log(codec, AV_LOG_DEBUG, "RTP Packetization Mode: %d\n", atoi(value));
        h264_data->packetization_mode = atoi(value);
        /*
           Packetization Mode:
           0 or not present: Single NAL mode (Only nals from 1-23 are allowed)
           1: Non-interleaved Mode: 1-23, 24 (STAP-A), 28 (FU-A) are allowed.
           2: Interleaved Mode: 25 (STAP-B), 26 (MTAP16), 27 (MTAP24), 28 (FU-A), and 29 (FU-B) are allowed.
         */
        if (h264_data->packetization_mode > 1)
            av_log(codec, AV_LOG_ERROR,
                   "Interleaved RTP mode is not supported yet.");
    } else if (!strcmp(attr, "profile-level-id")) {
        if (strlen(value) == 6) {
            char buffer[3];
            // 6 characters=3 bytes, in hex.
            uint8_t profile_idc;
            uint8_t profile_iop;
            uint8_t level_idc;

            buffer[0] = value[0]; buffer[1] = value[1]; buffer[2] = '\0';
            profile_idc = strtol(buffer, NULL, 16);
            buffer[0] = value[2]; buffer[1] = value[3];
            profile_iop = strtol(buffer, NULL, 16);
            buffer[0] = value[4]; buffer[1] = value[5];
            level_idc = strtol(buffer, NULL, 16);

            // set the parameters...
            av_log(codec, AV_LOG_DEBUG,
                   "RTP Profile IDC: %x Profile IOP: %x Level: %x\n",
                   profile_idc, profile_iop, level_idc);
            h264_data->profile_idc = profile_idc;
            h264_data->profile_iop = profile_iop;
            h264_data->level_idc = level_idc;
        }
    } else  if (!strcmp(attr, "sprop-parameter-sets")) {
        uint8_t start_sequence[]= { 0, 0, 1 };
        codec->extradata_size= 0;
        codec->extradata= NULL;

        while (*value) {
            char base64packet[1024];
            uint8_t decoded_packet[1024];
            uint32_t packet_size;
            char *dst = base64packet;

            while (*value && *value != ','
                   && (dst - base64packet) < sizeof(base64packet) - 1) {
                *dst++ = *value++;
            }
            *dst++ = '\0';

            if (*value == ',')
                value++;

            packet_size= av_base64_decode(decoded_packet, base64packet, sizeof(decoded_packet));
            if (packet_size) {
                uint8_t *dest = av_malloc(packet_size + sizeof(start_sequence) +
                                         codec->extradata_size +
                                         FF_INPUT_BUFFER_PADDING_SIZE);
                if(dest)
                {
                    if(codec->extradata_size)
                    {
                        // av_realloc?
                        memcpy(dest, codec->extradata, codec->extradata_size);
                        av_free(codec->extradata);
                    }

                    memcpy(dest+codec->extradata_size, start_sequence, sizeof(start_sequence));
                    memcpy(dest+codec->extradata_size+sizeof(start_sequence), decoded_packet, packet_size);
                    memset(dest+codec->extradata_size+sizeof(start_sequence)+
                           packet_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);

                    codec->extradata= dest;
                    codec->extradata_size+= sizeof(start_sequence)+packet_size;
                } else {
                    av_log(codec, AV_LOG_ERROR, "Unable to allocate memory for extradata!");
                    return AVERROR(ENOMEM);
                }
            }
        }
        av_log(codec, AV_LOG_DEBUG, "Extradata set to %p (size: %d)!", codec->extradata, codec->extradata_size);
    }
    return 0;
}