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• Cannot play video created by OpenCV (using Ubuntu 12.04)

  2 février 2015, par mcExchange

  I tried to write a video from a sequence of images created by OpenCV. However I cannot open the videos after writing them. I guess there is a codec issue. I find it extremely difficult where the error exactly comes from. Here is my code :

      Size size = Size(vecOfMats[0].rows,vecOfMats[0].cols);
  
      int codec = CV_FOURCC('D', 'I', 'V', 'X');
  
  
  
      VideoWriter videoWriter;
  
      videoWriter.open(outputFilename,codec,15.0,size,true);
  
  
  
      for(int z=0; z < vecOfMats.size(); z++)
  
      {
  
          videoWriter.write(vecOfMats[z]);
  
      }
  
      videoWriter.release();

  I also tried all of these codecs without success (either OpenCv could not find the codec or the video could not be opened) :

  int codec = CV_FOURCC('P','I','M','1');   // = MPEG-1 codec
  
  int codec = CV_FOURCC('M','J','P','G');   // = motion-jpeg codec - cannot be played by VLC
  
  int codec = CV_FOURCC('M', 'P', '4', '2');// = MPEG-4.2 codec - not found
  
  int codec = CV_FOURCC('D', 'I', 'V', '3');// = MPEG-4.3 codec - not found
  
  int codec = CV_FOURCC('D', 'I', 'V', 'X');// = MPEG-4 codec - cannot be played by VLC
  
  int codec = CV_FOURCC('U', '2', '6', '3');// = H263 codec - must have w/h = 4
  
  int codec = CV_FOURCC('I', '2', '6', '3');// = H263I codec - not found

  I even took the codec of a video opened via OpenCV previously (without success) :

  string filename = "/path/to/the/video/myVideo.avi";
  
  VideoCapture capture(filename);
  
  int ex = static_cast<int>(capture.get(CV_CAP_PROP_FOURCC));             // Get Codec Type- Int form
  
  char EXT[] = {(char)(ex &amp; 0XFF) , (char)((ex &amp; 0XFF00) >> 8),(char)((ex &amp; 0XFF0000) >> 16),(char)((ex &amp; 0XFF000000) >> 24), 0};// Transform from int to char via Bitwise operators
  
  cout&lt;&lt;"Codec: "&lt;code></int>

  I’m not even sure if the problem lies with my OpenCV or my Ubuntu :/.
  (I tried to open them using the default video player and vlc)

• avcodec/hevc : reduce memory for SAO

  12 janvier 2015, par Fabrice Bellard

  avcodec/hevc : reduce memory for SAO
  cherry picked from commit 5d9f79edef2c11b915bdac3a025b59a32082f409
  SAO edge filter uses pre-SAO pixel data on the left and top of the ctb, so
  
  this data must be kept available. This was done previously by having 2
  
  copies of the frame, one before and one after SAO.
  This commit reduces the storage to just that, instead of the previous whole
  
  frame.
  Commit message taken from patch by Christophe Gisquet <christophe.gisquet@gmail.com>
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/hevc.c
  • [DH] libavcodec/hevc.h
  • [DH] libavcodec/hevc_filter.c

• ffmpeg not creating audio file

  13 février 2015, par Dries

  I’m trying to write raw s16le audio to an audio file using ffmpeg.
  This is the command I’m using :

  ffmpeg -y -f s16le -acodec pcm_s16le -ar 44100 -ac 1 -i - -vn -ar 44100 -ac 1 OUTPUT_FILE.wav

  After this command is handled I use stdin to put data in the encoder like this :

  fwrite(samples_, sizeof(short int*), numSamples, audioffmpeg); 

  where samples_ is a short int* with a number of numSamples combined. At the moment I’m trying this per sample (so numSamples is 1).

  For some reason this isn’t creating a new file. Although, when I use a previously created file as input (so I don’t use stdin) it does create a new file.

  FFmpeg doesn’t seem to be outputting so I can’t give that