av_register_all();
    avformat_network_init();
    AVDictionary *option = NULL;
    const char* url = "rtsp://local_watcher/live.sdp";
    av_dict_set(&option, "rtsp_transport", "tcp", 0);
    // Open RTSP
    int err = avformat_open_input(&ctx, url, NULL, &option);

    av_dict_free(&option);

    int index = -1;
    for (int i = 0; i < ctx->nb_streams; i++) {
        if (ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
            index = i;
            break;
        }
    }