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• vaapi_h264 : Fix bit offset of slice data.

  2 avril 2016, par Mark Thompson

  vaapi_h264 : Fix bit offset of slice data.
  Commit ca2f19b9cc37be509d85f05c8f902860475905f8 modified the meaning of
  
  H264SliceContext.gb : it is now initialised at the start of the NAL unit
  
  header, rather than at the start of the slice header.  The VAAPI slice
  
  decoder uses the offset after parsing to determine the offset of the
  
  slice data in the bitstream, so with the changed meaning we no longer
  
  need to add the extra byte to account for the NAL unit header because
  
  it is now included directly.
  Signed-off-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  

  • [DH] libavcodec/vaapi_h264.c

• lavc : preserve the original private data in avcodec_copy_context()

  5 avril 2014, par Anton Khirnov

  lavc : preserve the original private data in avcodec_copy_context()
  If a non-NULL codec was passed to avcodec_alloc_context3(), private data
  
  will be already allocated in dest.
  

  • [DH] libavcodec/options.c

• Add Meta-Data to OpenCV VideoWriter as it records

  29 avril 2016, par Kells1986

  I have some simple code that records video at 3 frames per second using openCV 2.4. The code is running on a Raspberry Pi, which is going to be powered by a battery for about 5 minutes before it will die.

  Because the Raspberry Pi dies the video recording does not terminate gracefully, and it seems that the meta-data isn’t written to the file properly.

  mplayer is capable of playing the file back, but what I would like to do is post-process the video in some existing software. In order to be able to do that the software needs to extract the number of frames in the video from the meta-data, which it cannot do at present.

  Is there anyway of forcing openCV to write the meta-data as it records ? Or can I get mplayer / ffmpeg to fill in the gaps later ?

  Here is the code that records the video :

      VideoCapture cap(0); // open the default camera
  
      cap.set(CV_CAP_PROP_FPS, fps);
  
      cap.set(CV_CAP_PROP_FRAME_WIDTH, 1280);
  
      cap.set(CV_CAP_PROP_FRAME_HEIGHT, 720);
  
      if(!cap.isOpened())  // check if we succeeded
  
          return -1;
  
  
  
      Mat testFrame;
  
      cap >> testFrame;
  
      cap >> testFrame;
  
      cap >> testFrame;
  
  
  
      Size outSize = Size(testFrame.cols, testFrame.rows);
  
      VideoWriter writer(filename, CV_FOURCC('M','J','P','G'), fps, outSize, true);
  
  
  
      int count = 0;
  
      for(; ;)
  
      {
  
          Mat frame;
  
          cap >> frame; // get a new frame from camera
  
          writer.write(frame);    
  
      }