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• is there any way to take a screen shot of specific window on Mac ?

  5 novembre 2022, par youngho Park

  I wanted to capture only certain window using Imagemagick or Ffmpeg, but I heard that the x11 id needed for that is not supported on Mac.

  


  The purpose is to capture the application window so that all areas are displayed even if some areas are out of the display and are not visible.

  


• How to use ffmpeg capture screen (not command) ?

  16 novembre 2022, par Tom

  I am looking for example on the Internet, but none of the relevant examples can be run. Always I compile the no match ffmpeg version. Could someone share a example to learn ?

  


• Video encoding green screen

  22 août 2016, par Mohammad Abu Musa

  I am building a screen recorder, the input stream is formatted with PP_VIDEOFRAME_FORMAT_I420 and the output is formatted with AV_PIX_FMT_YUV420P below is the code I use to do the conversion

  const uint8_t* data = static_cast<const>(frame.GetDataBuffer());
  
      pp::Size size;
  
      frame.GetSize(&amp;size);
  
      uint32_t buffersize = frame.GetDataBufferSize();
  
  
  
  
  
      if (is_recording_) {
  
          vpx_codec_iter_t iter = NULL;
  
          const vpx_codec_cx_pkt_t *pkt;
  
          // copy the pixels into our "raw input" container.
  
          int bytes_filled = avpicture_fill(&amp;pic_raw, data, AV_PIX_FMT_YUV420P, out_width, out_height);
  
          if(!bytes_filled) {
  
              Logger::Log("Cannot fill the raw input buffer");
  
              return;
  
          }
  
  
  
          if(vpx_codec_encode(&amp;codec, &amp;raw, frame_cnt, 1, flags, VPX_DL_REALTIME))
  
                die_codec(&amp;codec, "Failed to encode frame");
  
  
  
          while( (pkt = vpx_codec_get_cx_data(&amp;codec, &amp;iter)) ) {
  
              switch(pkt->kind) {
  
                  case VPX_CODEC_CX_FRAME_PKT:
  
                      glb_app_thread.message_loop().PostWork(callback_factory_.NewCallback(&amp;EncoderInstance::write_ivf_frame_header, pkt));
  
                      glb_app_thread.message_loop().PostWork(callback_factory_.NewCallback(&amp;EncoderInstance::WriteFile, pkt));
  
                      break;
  
                  default:break;
  
              }
  
          }
  
  
  
          frame_cnt++;
  
  </const>

  I have three questions :

  1- Is the conversion is done correctly ? do I have to investigate image formats more ? are data channels mapped correctly.

  2- What causes the green screen to show ? what does it mean ?

  3- Is this a thread issue ? I mean is data passed correctly and the conversion is done correctly but the threads are racing