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• Get Total number of frames and FPS faster than with OpenCV library in C++

  20 juillet 2018, par daniels_pa

  I need to check which video can be analyzed and which cannot given the total number of frames in a video and the fps of the video. I created a c++ program to do the checking. Analyzing each video is not an option since analyzing is time consuming.

  I used the OpenCV library for starters :

      cv::VideoCapture vid_to_analyze;
  
      vid_to_analyze.open( me_vid.vid_path.string() );
  
      me_vid.total_frames= static_cast<int>(vid_to_analyze.get(CV_CAP_PROP_FRAME_COUNT));
  
      me_vid.fps=vid_to_analyze.get(CV_CAP_PROP_FPS);
  
  
  
      if (!vid_to_analyze.isOpened())
  
      {
  
          std::cout &lt;&lt; "Skipping vid: "&lt;&lt; me_vid.vid_path.string()&lt;&lt;", couldn't open it" &lt;&lt; std::endl;
  
      }
  
      if (me_vid.fps != me_vid.fps || me_vid.fps &lt;= 0)
  
      {
  
          std::cout &lt;&lt; "For video " &lt;&lt; me_vid.vid_path.string() &lt;&lt; std::endl;
  
          std::cout &lt;&lt; "FPS of the video file cannot be determined, assuming 30"&lt;&lt; std::endl;
  
          me_vid.fps = 30;
  
      }
  
  
  
      vid_to_analyze.release();
  
  </int>

  However when debugging it becomes painfully slow (the program is faster running without the debugger attached but still very slow given the number of videos it needs to cover). I think that has something to do with 4 threads being created and deleted each time a video is opened (released).

  How to get total number of frames and fps in a faster manner ( without actually creating 4 threads !!) if i am not interested in actually grabbing frames from the video just the number of frames and fps.

  Is there a way to use ffmpeg library from c++, would that be faster and where to start ?

  EDIT : Valgrind seems to agree since (Ir=)91.66% of time spend in the vid_to_analyze.open phase

• avcodec/vc1 : change the internal ordering of blocks within a macroblock

  20 juin 2018, par Jerome Borsboom

  avcodec/vc1 : change the internal ordering of blocks within a macroblock
  The overlap filter needs to cover a full macroblock vertical edge when the
  
  FIELDTX value for two neighbouring macroblocks is not equal. By changing
  
  the internal ordering of the blocks from row major to column major, we do
  
  not need to reinterlace a FIELDTX coded macroblock before running the overlap
  
  filter.
  Signed-off-by : Jerome Borsboom <jerome.borsboom@carpalis.nl>
  

  • [DH] libavcodec/vc1_block.c

• error when running "imageio.plugins.ffmpeg.download()"

  14 juin 2018, par Maryeveh

  I am trying to run the command imageio.plugins.ffmpeg.download() after installing moviepy and imageio and importing imageio without error.
  I keep getting the following error and cannot figure out the solution :

  Imageio: 'ffmpeg-osx-v3.2.4' was not found on your computer; downloading it now.
  
  Error while fetching file: <urlopen error="error" certificate="certificate" verify="verify" failed="failed">.
  
  Error while fetching file: <urlopen error="error" certificate="certificate" verify="verify" failed="failed">.
  
  Error while fetching file: <urlopen error="error" certificate="certificate" verify="verify" failed="failed">.
  
  Error while fetching file: <urlopen error="error" certificate="certificate" verify="verify" failed="failed">.
  
  
  
      ---------------------------------------------------------------------------
  
      IOError                                   Traceback (most recent call last)
  
       in <module>()
  
            3 get_ipython().magic(u'matplotlib inline')
  
            4 import imageio
  
      ----> 5 imageio.plugins.ffmpeg.download()
  
            6 import matplotlib
  
            7 import matplotlib.pyplot as plt
  
  
  
      /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/imageio/plugins/ffmpeg.pyc in download(directory, force_download)
  
          71     get_remote_file(fname=fname,
  
           72                     directory=directory,
  
      ---> 73                     force_download=force_download)
  
          74 
  
          75 
  
  
  
      /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/imageio/core/fetching.pyc in get_remote_file(fname, directory, force_download, auto)
  
        125             return filename
  
         126     else:  # pragma: no cover
  
     --> 127         _fetch_file(url, filename)
  
         128         return filename
  
         129 
  
  
  
      /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/imageio/core/fetching.pyc in _fetch_file(url, file_name, print_destination)
  
          181         raise IOError('Unable to download %r. Perhaps there is a no internet '
  
          182                       'connection? If there is, please report this problem.' %
  
      --> 183                       os.path.basename(file_name))
  
          184 
  
          185 
  
  </module></urlopen></urlopen></urlopen></urlopen>

  IOError : Unable to download ’ffmpeg-osx-v3.2.4’. Perhaps there is a
  no internet connection ? If there is, please report this problem.

  I tried all the solutions I could think of or/and found online, including the ones described here ffmpeg installation on macOS for MoviePy fails with SSL error, but nothing helped.
  Does anyone found another solution ?

  Thanks