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• 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

• Colors are not correct for FFMPEG videos

  23 août 2016, par Mohammad Abu Musa

  I am writing a screen recorder, I managed to record the videos and export them as webm but I have a color and timing issue(which I am working on).

  For coloring the video frames I get are formatted with FORMAT_I420 which I transfer them to YUV sources and encode them as the following code

  void EncoderInstance::OnGetFrame(int32_t result, pp::VideoFrame frame) {
  
      if (result != PP_OK)
  
          return;
  
  
  
      //const uint8_t* data = static_cast<const>(frame.GetDataBuffer());
  
      unsigned char* data = static_cast<unsigned>(frame.GetDataBuffer());
  
      pp::Size size;
  
      frame.GetSize(&amp;size);
  
      uint32_t buffersize = frame.GetDataBufferSize();
  
      //frame.GetFormat() == PP_VIDEOFRAME_FORMAT_BGRA);
  
      //Logger::Log("Format is :%d", frame.GetFormat());
  
      //PP_VIDEOFRAME_FORMAT_I420
  
  
  
  
  
  
  
      Logger::Log("stream received is: %02X", data);
  
  
  
      if (is_recording_) {
  
          vpx_codec_iter_t iter = NULL;
  
          const vpx_codec_cx_pkt_t *pkt;
  
  
  
  
  
          int iSizeY = out_width * out_height;
  
          int iSizeUV = (out_width * out_height)/4;
  
          unsigned char* pY = data;
  
          unsigned char* pU = data + iSizeY; // there are width * height Y components
  
          unsigned char* pV = data + iSizeUV;    // skip the U components
  
  
  
          Logger::Log("pY: %02X", pY);
  
          Logger::Log("pU: %02X", pU);
  
          Logger::Log("pV: %02X", pV);
  
  
  
  
  
          // copy the pixels into our "raw input" container.
  
          int bytes_filled = avpicture_fill(&amp;pic_raw, NULL, AV_PIX_FMT_YUV420P, out_width, out_height);
  
          pic_raw.data[0] = pY;
  
          pic_raw.data[1] = pU;
  
          pic_raw.data[2] = pU;
  
  
  
          Logger::Log("bytes filled: %d", bytes_filled);
  
  
  
          if(!bytes_filled) {
  
              Logger::Log("Cannot fill the raw input buffer");
  
              return;
  
          }
  
  
  
          // convert to i420 for vp8
  
          int h = sws_scale(sws, pic_raw.data, pic_raw.linesize, 0, out_height, raw.planes, raw.stride);
  
  
  
          if(h != out_height) {
  
              Logger::Log("scale failed: %d", h);
  
              return;
  
          }
  
  
  
  
  
  
  
          Logger::Log("Picture Raw data is: %d", pic_raw.data);
  
  
  
          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:
  
                      Logger::Log("Compressed buffer is %02X:",pkt->data.frame.buf);
  
                      Logger::Log("Compressed buffer size %02X:",pkt->data.frame.sz);
  
  
  
                      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));
  
      }
  
  }
  
  </unsigned></const>

  Here is a screenshot of an image I got from the video generated

• lavu/timestamp : Avoid C++-unfriendly code in user header

  31 août 2016, par Mark Thompson

  lavu/timestamp : Avoid C++-unfriendly code in user header
  Including this header in a C++11 program (inside extern "C") will
  
  throw an error because it looks like a user-defined literal.  Add a
  
  space between the two tokens to avoid the problem.
  

  • [DH] libavutil/timestamp.h