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• avio_open() function returns -138

  8 avril 2024, par checkright

  When I use ffmpeg4.4.1 to push rtmp to the desktop, the program returns -138 when running avio_open().I use dshow's screen-capture-recorder on the input side. My purpose is to capture the desktop in real time and use rtmp to push the stream.

  


      avdevice_register_all();
    avformat_network_init();

    AVFormatContext* pFmtCtx_In = nullptr;
    AVFormatContext* pFmtCtx_Out = nullptr;
    AVInputFormat*   pInFmt  = nullptr;
    AVDictionary* options = nullptr;
    int nVideoIndex          = -1;
    int              ret     = 0;

    AVCodecParameters* pCodecParam = nullptr;
    AVCodecContext   * pCodecCtx   = nullptr;
    AVCodec          * pCodec      = nullptr;

    AVFrame* pFrame    = av_frame_alloc();
    AVFrame* pFrameRGB = av_frame_alloc();
    AVPacket* pkt      = nullptr;

    pFrame    = av_frame_alloc();
    pFrameRGB = av_frame_alloc();
    pkt       = nullptr;
    img_convert_ctx = nullptr;

    pFmtCtx_In = avformat_alloc_context();
    if(!pFmtCtx_In)
    {
        qDebug() << "create AVFormatContext failed." ;
        return;
    }

    QString urlString = QString("video=screen-capture-recorder");
    const char* rtmpAddress = "rtmp://192.168.0.136:8554/myapp/test";
    
    if(1){
        pInFmt = const_cast(av_find_input_format("dshow"));
        ret = avformat_open_input(&pFmtCtx_In, urlString.toStdString().c_str(), pInFmt, nullptr);
    }else{
        pInFmt = const_cast(av_find_input_format("gdigrab"));
        av_dict_set(&options, "video_device_index", "1", 0);  
        av_dict_set(&options, "offset_x", "1920", 0);
        av_dict_set(&options, "offset_y", "0", 0);
        av_dict_set(&options, "draw_mouse", "1", 0);
        av_dict_set(&options, "video_size", "1920x1080", 0);
        ret = avformat_open_input(&pFmtCtx_In, "desktop", pInFmt, &options);
    }

    if(!pInFmt)
    {
        qDebug() << "find AVInputFormat failed." ;
        return;
    }

    if(ret < 0)
    {
        qDebug() << "open camera failed."<nb_streams; i++){
        if(pFmtCtx_In->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO){
            nVideoIndex = i;
            continue;
        }
    }

    if(nVideoIndex == -1){
        qDebug() << "cannot find video stream." ;
        return;
    }


    pCodecParam = pFmtCtx_In->streams[nVideoIndex]->codecpar;
    pCodec = avcodec_find_decoder(pCodecParam->codec_id);
    if(!pCodec)
    {
        qDebug() << "cannot find codec." ;
        return;
    }

    ret = avformat_alloc_output_context2(&pFmtCtx_Out, NULL, "flv", rtmpAddress);
    //    ret = avformat_alloc_output_context2(&pFmtCtx_Out, NULL, "rtsp", rtmpAddress);
    if (ret < 0) {
        qDebug() << "cannot avformat_alloc_output_context2." ;
        return ;
    }

    for (int i = 0; i < pFmtCtx_In->nb_streams; i++) {
        AVStream *outStream = avformat_new_stream(pFmtCtx_Out, pFmtCtx_In->streams[i]->codec->codec);
        if (!outStream) {
            qDebug() << "cannot outStream." ;

            return ;
        }

        ret = avcodec_parameters_copy(outStream->codecpar, pFmtCtx_In->streams[i]->codecpar);
        if (ret < 0) {
             qDebug() << "cannot avcodec_parameters_copy." ;
            return ;
        }
        outStream->codec->codec_tag = 0;
    }
  
    av_dump_format(pFmtCtx_Out, 0, rtmpAddress, 1);

    ret = avio_open(&pFmtCtx_Out->pb, rtmpAddress, AVIO_FLAG_WRITE);
    if (ret < 0) {
        qDebug() << "cannot avio_open." <code>

  


  An error occurs here.According to the data, the problem occurs at the input end, and the input end can display the desktop normally. How can I make it run successfully ? How do I need to modify the above code ?

  


• av_guess_format h264 returns NULL on Android

  21 mai 2013, par Miguel Angel

  executing this code :

  av_log_set_callback(_log_callback);
  
  av_register_all();
  
  avcodec_register_all();
  
  LOG(avcodec_configuration());
  
  AVOutputFormat * fmt = av_guess_format( "h264", NULL, NULL );

  And showing in my log file the next configuration :

   --target-os=linux --disable-doc --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-avfilter --disable-everything --enable-libx264 --enable-encoder=libx264 --enable-decoder=h264 --enable-gpl ....

  av_guess_format is returning NULL.

  Any suggestion ?
  many thanks

• ffprobe returns coded_picture_number with a frame missing

  26 janvier 2018, par Hélder

  While using ffprobe to get the pict_type and coded_picture_number I noticed while doing a for loop in python that one of the coded_picture_number was missing.

  This is the command used :

  ffprobe foreman.m4v -show_frames | grep -E 'pict_type|coded_picture_number' > output.txt

  And I get returned all frame number with exception of one :

  coded_picture_number=290
  
  pict_type=P
  
  coded_picture_number=289
  
  pict_type=B
  
  coded_picture_number=292
  
  pict_type=P
  
  coded_picture_number=291
  
  pict_type=B
  
  coded_picture_number=294
  
  pict_type=P
  
  coded_picture_number=293
  
  pict_type=B
  
  coded_picture_number=297
  
  pict_type=B
  
  coded_picture_number=296

  The total is 297 coded_picture_number, where does the 295 go ? Does anyone know how to get it ? It causes errors in python when taking ranges and trying to read the image from the data frame.

  If it is possible to have a smooth numbering per pict_type would be perfect. Any clue ?