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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

• FFmpeg sws_scale on changed area

  1er octobre 2016, par useprxf

  I was using sws_scale to convert a group of RGB32 images to YUV420 format. Each image is very similar to the previous one and they only differ on a rectangle region Q.

  My question is how to utilize Q to speed up the conversion process ? An additional parameter should be added to sws_scale function.

  sws_scale( ctx, in_plane, in_stride, sliceY, height, out_plane, out_stride, Q){
  
      // parameter out_plane stores the YUV420 data of previous image
  
      Instead of scanning the whole image, scan through rectangle Q{
  
          Do conversion
  
      }
  
  }

• avfilter/vf_v360 : add cylindrical equal area format

  30 juin 2021, par Paul B Mahol

  avfilter/vf_v360 : add cylindrical equal area format
  

  • [DH] doc/filters.texi
  • [DH] libavfilter/v360.h
  • [DH] libavfilter/vf_v360.c