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• FFMPEG Green Screen from raw pictures

  21 août 2016, par Mohammad Abu Musa

  I am writing a screen recorder, I get raw data from Chrome and I want to covert it to webm files. I manged successfully to export the videos with the correct periods but the issue that I get a green screen instead of the screen capture. I am not sure what could be wrong.

  Is it writing to file ? or passing the parameters to fwrite function ?

  void EncoderInstance::OnGetFrame(int32_t result, pp::VideoFrame frame) {
  
      if (result != PP_OK)
  
          return;
  
  
  
      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++;
  
      }
  
  
  
      video_track_.RecycleFrame(frame);
  
      if (need_config_) {
  
          ConfigureTrack();
  
          need_config_ = false;
  
      } else {
  
          video_track_.GetFrame(
  
                  callback_factory_.NewCallbackWithOutput(
  
                          &amp;EncoderInstance::OnGetFrame));
  
      }
  
  }
  
  </const>

• Passing pointer to thread via message_loop

  21 août 2016, par Mohammad Abu Musa

  I am using FFMPEG to encode a video, I got a green screen for the packets which I think it means I am getting empty buffer. I suspect I am passing the parameters wrong. I want help in getting the parameters passed correctly.

      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(&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(&codec, &raw, frame_cnt, 1, flags, VPX_DL_REALTIME))
  
            die_codec(&codec, "Failed to encode frame");
  
  
  
      while( (pkt = vpx_codec_get_cx_data(&codec, &iter)) ) {
  
          switch(pkt->kind) {
  
              case VPX_CODEC_CX_FRAME_PKT:
  
                  glb_app_thread.message_loop().PostWork(callback_factory_.NewCallback(&EncoderInstance::write_ivf_frame_header, pkt));
  
                  glb_app_thread.message_loop().PostWork(callback_factory_.NewCallback(&EncoderInstance::WriteFile, pkt));
  
                  break;
  
              default:break;
  
          }
  
      }

  for the event handler

  void EncoderInstance::WriteFile(int32_t result, const vpx_codec_cx_pkt_t *pkt){
  
      lock_file_.Acquire();
  
      (void) fwrite(pkt->data.frame.buf, 1, pkt->data.frame.sz, outfile);
  
      Logger::Log("Packet written");
  
      lock_file_.Release();
  
  
  
  }

  My question is, am I passing the argument pkt correctly ? or should I put these packets into a queue then let the writeFile function work on the queue.

• 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