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• Memory leak when using av_frame_get_buffer()

  19 juillet 2018, par Alec Matthews

  I am making a simple video player with ffmpeg. I have noticed that there is a memory leak originating in libavutil. Because ffmpeg is a mature library I assume that I am allocating a new frame incorrectly. The documentation is also vague about freeing the buffer that is created when you call av_frame_get_buffer(). Below is the code I am using to decode the video and queue it up for display on the UI thread.

  DWORD WINAPI DecoderThread(LPVOID lpParam)
  
  {
  
      AVFrame *frame = NULL;
  
      AVPacket pkt;
  
  
  
      SwsContext *swsCtx = NULL;
  
      UINT8 *buffer = NULL;
  
      INT iNumBytes = 0;
  
  
  
      INT result = 0;
  
  
  
      frame = av_frame_alloc();
  
  
  
      av_init_packet(&pkt);
  
      pkt.data = NULL;
  
      pkt.size = 0;
  
  
  
      // Create scaling context
  
      swsCtx = sws_getContext(codecCtx->width, codecCtx->height, codecCtx->pix_fmt, codecCtx->width, codecCtx->height, AV_PIX_FMT_BGR24, SWS_BICUBIC, NULL, NULL, NULL);
  
  
  
     while (av_read_frame(fmtCtx, &pkt) >= 0) {
  
          if (pkt.stream_index == videoStream) {
  
              result = avcodec_send_packet(codecCtx, &pkt);
  
  
  
              while (result >= 0) {
  
                  result = avcodec_receive_frame(codecCtx, frame);
  
                  if (result == AVERROR(EAGAIN) || result == AVERROR_EOF) {
  
                      break;
  
                  } else if (result < 0) {
  
                      // another error.
  
                  }
  
                  // Create a new frame to store the RGB24 data.
  
                  AVFrame *pFrameRGB = av_frame_alloc();
  
                  // Allocate space for the new RGB image.
  
                  //av_image_alloc(pFrameRGB->data, pFrameRGB->linesize, codecCtx->width, codecCtx->height, AV_PIX_FMT_BGR24, 1);
  
                  // Copy all of the properties from the YUV420P frame.
  
                  av_frame_copy_props(pFrameRGB, frame);
  
                  pFrameRGB->width = frame->width;
  
                  pFrameRGB->height = frame->height;
  
                  pFrameRGB->format = AV_PIX_FMT_BGR24;
  
                  av_frame_get_buffer(pFrameRGB, 0);
  
  
  
                  // Convert fram from YUV420P to BGR24 for display.
  
                  sws_scale(swsCtx, (const UINT8* const *) frame->data, frame->linesize, 0, codecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
  
  
  
                  // Queue thr BGR frame for drawing by the main thread.
  
                  AddItemToFrameQueue(pFrameRGB);
  
  
  
                  av_frame_unref(frame);
  
              }
  
          }
  
         while (GetQueueSize() > 100) {
  
              Sleep(10);
  
         }
  
     }
  
  
  
      CloseFrameQueue();
  
  
  
      av_frame_free(&frame);
  
     avcodec_close(codecCtx);
  
     avformat_close_input(&fmtCtx);
  
  
  
      return 0;
  
  }

  Is there a better way to allocate a new frame for holding the post sws_scale() transformation ?

  There is a similar stackoverflow question that uses mostly depreciated function calls. I can’t seem to find any answers that conform to the new version of ffmpeg in the documentation. Any help would be appreciated.

• Compress video like whatsapp

  12 février 2016, par Copernic

  I’m not an expert in Video Editing but what I want to understand the logic of Whatsapp video processing.

  First of all I have noticed that whatever the file is, Whatsapp sets the limit of Uploaded videos to 16MO, after which whatsapp crops the video to not exceed the limit. is this a convention or it’s a personal choice ?

  Secondly, When a video is recorded using the Camera it’s not compressed by default, so whatsapp compresses it using FFMPEG I guess, and it takes no time. (tried for a video of 1min 1920x1080 with 125MO of size, becomes 640x360 with 5MO of size in no time, and the upload starts automatically).. how may they do this ? and why the choice of 640x360, It seems to me very fast for 2 asynchronous tasks : Compression + Upload.

  When I run the compression command ffmpeg -y -i in.mp4 -codec:v libx264 -crf 23 -preset medium -codec:a libfdk_aac -vbr 4 -vf scale=-1:640,format=yuv420p out.mp4 it takes approximatively 1 min and the video is being rotated !! :D

  Finally, when we download a video from Youtube it’s already compressed (I guess) and whatsapp doesn’t even try to compress it. So I think that it automatically detects thats the video is compressed. How can we detect this ?

  Thank you.

• Compress video like whatsapp

  10 juillet 2021, par user1079425

  I'm not an expert in Video Editing but what I want to understand the logic of Whatsapp video processing.

  



  First of all I have noticed that whatever the file is, Whatsapp sets the limit of Uploaded videos to 16MB, after which whatsapp crops the video to not exceed the limit. is this a convention or it's a personal choice ?

  



  Secondly, When a video is recorded using the Camera it's not compressed by default, so whatsapp compresses it using FFMPEG I guess, and it takes no time. (tried for a video of 1min 1920x1080 with 125MB of size, becomes 640x360 with 5MB of size in no time, and the upload starts automatically).. how may they do this ? and why the choice of 640x360, It seems to me very fast for 2 asynchronous tasks : Compression + Upload.

  



  When I run the compression command ffmpeg -y -i in.mp4 -codec:v libx264 -crf 23 -preset medium -codec:a libfdk_aac -vbr 4 -vf scale=-1:640,format=yuv420p out.mp4 it takes approximatively 1 min and the video is being rotated !! :D

  



  Finally, when we download a video from Youtube it's already compressed (I guess) and whatsapp doesn't even try to compress it. So I think that it automatically detects thats the video is compressed. How can we detect this ?

  



  Thank you.