使用FFmpeg推送RTSP流

    av_register_all();
    avformat_network_init();
    AVOutputFormat *ofmt = NULL;
    //输入对应一个AVFormatContext，输出对应一个AVFormatContext  
    //（Input AVFormatContext and Output AVFormatContext）  
    AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
    AVPacket pkt;
    const char *in_filename, *out_filename;
    int ret, i;
    int videoindex = -1;
    int frame_index = 0;
    int64_t start_time = 0;

    AVDictionary *dict = NULL;

    //输入URL（Input file URL）  
    in_filename = "receive.mp4";
    
    //输出 URL（Output URL）[RTMP]   //out_filename = "rtp://233.233.233.233:6666";//输出 URL（Output URL）[UDP]
    out_filename = "rtsp://192.168.222.222:554/123456.sdp";                                                   
    //输入（Input）  
    if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {
        printf("Could not open input file.");
        goto end;
    }
    if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
        printf("Failed to retrieve input stream information");
        goto end;
    }

    for (i = 0; i<ifmt_ctx->nb_streams; i++)
        if (ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
            videoindex = i;
            break;
        }

    av_dump_format(ifmt_ctx, 0, in_filename, 0);

    //输出（Output）  
     
    avformat_alloc_output_context2(&ofmt_ctx, NULL, "rtsp", out_filename); 
                                                                         
    if (!ofmt_ctx) {
        printf("Could not create output context\n");
        ret = AVERROR_UNKNOWN;
        goto end;
    }
    ofmt = ofmt_ctx->oformat;
    for (i = 0; i < ifmt_ctx->nb_streams; i++) {
        //根据输入流创建输出流（Create output AVStream according to input AVStream）  
        AVStream *in_stream = ifmt_ctx->streams[i];
        
        AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);
        if (!out_stream) {
            printf("Failed allocating output stream\n");
            ret = AVERROR_UNKNOWN;
            goto end;
        }
        //复制AVCodecContext的设置（Copy the settings of AVCodecContext）  
        ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
        if (in_stream->codec->codec_id == AV_CODEC_ID_NONE) {
            out_stream->codec->codec_id = AV_CODEC_ID_AAC;
        }
        
        if (ret < 0) {
            printf("Failed to copy context from input to output stream codec context\n");
            goto end;
        }
        out_stream->codec->codec_tag = 0;
        if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
            out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
    }
    //Dump Format------------------  
    av_dump_format(ofmt_ctx, 0, out_filename, 1);
    //打开输出URL（Open output URL）  

    if (!(ofmt->flags & AVFMT_NOFILE)) {
        ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);
        if (ret < 0) {
            printf("Could not open output URL '%s'", out_filename);
            goto end;
        }
    }

    av_dict_set(&dict, "rtsp_transport","tcp",0);
    av_dict_set(&dict, "muxdelay", "0.1", 0);

    ofmt_ctx->audio_codec_id = ofmt_ctx->oformat->audio_codec;
    ofmt_ctx->video_codec_id = ofmt_ctx->oformat->video_codec;
    ret = avformat_write_header(ofmt_ctx, &dict);
    if (ret < 0) {
        printf("Error occurred when opening output URL\n");
        goto end;
    }

    start_time = av_gettime();
    while (1) {
        AVStream *in_stream, *out_stream;
        //获取一个AVPacket（Get an AVPacket）  
        ret = av_read_frame(ifmt_ctx, &pkt);
        if (ret < 0) {
            printf("----=%i-----=%i-------\n",GetCurrentThreadId(), frame_index);
            break;
        }
            
        //FIX：No PTS (Example: Raw H.264)  
        //Simple Write PTS  
        if (pkt.pts == AV_NOPTS_VALUE) {
            //Write PTS  
            AVRational time_base1 = ifmt_ctx->streams[videoindex]->time_base;
            //Duration between 2 frames (us)  
            int64_t calc_duration = (double)AV_TIME_BASE / av_q2d(ifmt_ctx->streams[videoindex]->r_frame_rate);
            //Parameters  
            pkt.pts = (double)(frame_index*calc_duration) / (double)(av_q2d(time_base1)*AV_TIME_BASE);
            pkt.dts = pkt.pts;
            pkt.duration = (double)calc_duration / (double)(av_q2d(time_base1)*AV_TIME_BASE);
        }
        //Important:Delay  
        if (pkt.stream_index == videoindex) {
            AVRational time_base = ifmt_ctx->streams[videoindex]->time_base;
            AVRational time_base_q = { 1,AV_TIME_BASE };
            int64_t pts_time = av_rescale_q(pkt.dts, time_base, time_base_q);
            int64_t now_time = av_gettime() - start_time;
            if (pts_time > now_time)
                av_usleep(pts_time - now_time);

        }

        in_stream = ifmt_ctx->streams[pkt.stream_index];
        out_stream = ofmt_ctx->streams[pkt.stream_index];
        /* copy packet */
        //转换PTS/DTS（Convert PTS/DTS）  
        pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
        pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
        pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);
        pkt.pos = -1;
        //Print to Screen  
        if (pkt.stream_index == videoindex) {
            //printf("Send %8d video frames to output URL\n", frame_index);
            frame_index++;
        }
        //ret = av_write_frame(ofmt_ctx, &pkt);  
        ret = av_interleaved_write_frame(ofmt_ctx, &pkt);

        if (ret < 0) {
            printf("Error muxing packet\n");
            break;
        }

        av_free_packet(&pkt);

    }
    //写文件尾（Write file trailer）  
    av_write_trailer(ofmt_ctx);
end:
    avformat_close_input(&ifmt_ctx);
    /* close output */
    if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
        avio_close(ofmt_ctx->pb);
    avformat_free_context(ofmt_ctx);
    if (ret < 0 && ret != AVERROR_EOF) {
        printf("Error occurred.\n");
        return -1;
    }
    return 0;