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• ffmpeg sws_scale converting from YUV420P to RGB24 results in wrong color values

  3 novembre 2016, par Drazurh

  I’m using sws_scale to convert a video from YUV420P to RGB24. The resulting RGB values are wrong, looking much more saturated/contrasted. For example, the first pixel should have an RGB value of (223,73,30) but using sws_scale results in (153,0,0).

  Here’s the code I’m using :

  uint8_t *buffer = NULL;
  
  int numBytes;
  
  // Determine required buffer size and allocate buffer
  
  numBytes=avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,
  
                             pCodecCtx->height);
  
  buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
  
  
  
  // Assign appropriate parts of buffer to image planes in pFrameRGB
  
  // Note that pFrameRGB is an AVFrame, but AVFrame is a superset
  
  // of AVPicture
  
  std::cout << "Filling picture of size " << pCodecCtx->width <<" x "<height << std::endl;
  
  avpicture_fill((AVPicture *)pFrameRGB, buffer, PIX_FMT_RGB24,
  
                  pCodecCtx->width, pCodecCtx->height);
  
  
  
  
  
  
  
  // initialize SWS context for software scaling
  
  std::cout << "initializing SWS context\n";
  
  sws_ctx = sws_getContext(pCodecCtx->width,
  
      pCodecCtx->height,
  
      pCodecCtx->pix_fmt,
  
      pCodecCtx->width,
  
      pCodecCtx->height,
  
      PIX_FMT_RGB24,
  
      SWS_FAST_BILINEAR,
  
      NULL,
  
      NULL,
  
      NULL
  
  );
  
  
  
  while(frameFinished == 0)
  
  {
  
      if(av_read_frame(pFormatCtx, &packet)<0){
  
          std::cerr << "Could not read frame!\n";
  
          return false;
  
      }
  
  
  
      if(packet.stream_index==videoStream)
  
      {
  
          avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
      }
  
  
  
  }
  
  
  
  sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,
  
            pFrame->linesize, 0, pCodecCtx->height,
  
            pFrameRGB->data, pFrameRGB->linesize);

  The values in pFrameRGB are incorrect. I’ve tried troubleshooting this for hours :-( Any ideas on how to track down my mistake ?

  Here’s a link to the repo. The offending code is in Icosahedron Video Player/mesh.cpp, Mesh::LoadVideo and Mesh::NextFrame().

• Drop unreachable break and return statements

  13 mars 2015, par Diego Biurrun

  Drop unreachable break and return statements
  

  • [DBH] libavcodec/bmvvideo.c
  • [DBH] libavcodec/hevc_sei.c
  • [DBH] libavcodec/indeo3.c
  • [DBH] libavcodec/sanm.c
  • [DBH] libavformat/rtpproto.c
  • [DBH] libavformat/rtspdec.c
  • [DBH] libavformat/smush.c
  • [DBH] libavutil/opt.c

• Wrong play video after trimmed with ffmpeg

  1er novembre 2016, par Os Sony Louis

  After I cut a video with ffmpeg
  HTML5 video is not displayed video I trim
  this is the source code

  <?php exec("ffmpeg.exe"); 
  
  unlink("../output/dir/cut1.mp4");
  
  clearstatcache();
  
  exec("ffmpeg -ss 00:01:00 -i ../input/1.mp4 -to 00:03:00 -c copy ../output/dir/cut1.mp4");
  
  ?>
  
  <video width="300" height="auto" controls="controls">
  
  <source src="../output/dir/cut1.mp4" type="video/mp4">
  
  </source></video>

  result :
  Result1

  exec("ffmpeg -ss 00:01:00 -i ../input/1.mp4 -to 00:05:00 -c copy ../output/dir/cut1.mp4");

  result :

  Result2

  i must open the new tab to get the new duration from video i’ve trimmed
  i can’t get the new duration in the same tab even i’ve refreshed it
  how come ?