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• OpenCV in Python on Windows does not report correct video properties from VideoReader

  24 décembre 2015, par Mircea Davidescu

  I am running into a problem with using VideoReader in OpenCV with Python. Many of the properties that I should be able to get from the video reader are either somehow invalid (returning 0), or return the wrong number. For instance.

  vidFile = cv2.VideoCapture('movie.avi')
  
  vidFile.get(cv2.CAP_PROP_FRAME_COUNT)
  
  vidFile.get(cv2.CAP_PROP_FPS)

  The first get command returns a wrong value, while the second get command returns 0. The output of the ffprobe command is given below :

  built with gcc 5.2.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls 
  
  --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm 
  
  --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus 
  
  --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab 
  
  --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 
  
  --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enable-zlib
  
    libavutil      55.  5.100 / 55.  5.100
  
    libavcodec     57. 12.100 / 57. 12.100
  
    libavformat    57. 11.100 / 57. 11.100
  
    libavdevice    57.  0.100 / 57.  0.100
  
    libavfilter     6. 14.101 /  6. 14.101
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.100 /  2.  0.100
  
    libpostproc    54.  0.100 / 54.  0.100
  
  Input #0, avi, from 'movie.avi':
  
    Metadata:
  
      encoder         : Lavf55.0.100
  
    Duration: 00:31:59.97, start: 0.000000, bitrate: 24321 kb/s
  
      Stream #0:0: Video: mjpeg (MJPG / 0x47504A4D), yuvj420p(pc, bt470bg/unknown/unknown), 1392x1040 [SAR 1:1 DAR 87:65], 24316 kb/s, 30 fps, 30 tbr, 30 tbn, 
  
  30 tbc

  I am running a Windows 10 machine with Python 2.7.11 (Anaconda 2.4.1 64-bit). I have installed OpenCV 3.0.0 according the instructions provided here. Because I am using the VideoReader feature I also added C :\opencv\sources\3rdparty\ffmpeg to the system PATH and renamed both opencv_ffmpeg300.dll and opencv_ffmpeg_x64.dll to opencv_ffmpeg300.dll and opencv_ffmpeg300_64.dll respectively, as specified here.

  Thank you for your help with this problem !

• FFMPEG for Windows - suggestions for how to overcome the " No such file or directory" issue

  11 mars 2023, par Scott Hatton

  I am using FFMPEG (Windows version)

  


  I have files called 'MCR_0400.jpeg' numbered sequentially up to 'MCR_0450.jpeg'

  


  When I run :
ffmpeg -i 'MCR_%4d.jpeg' -start_number 0400 -c:v libx264 out.mp4

  


  it returns :
Could find no file with path 'MCR_%4d.jpeg' and index in the range 0-4
'MCR_%4d.jpeg' : No such file or directory

  


  I have spend the day trying all sorts of variations on the file name parameter : with and without quotes, full Windows path to it so I assume I'm doing something really stupidly wrong.

  


  But I just cannot fathom it.

  


  Can anybody help ?

  


• ffmpeg causes browser to hang up ?

  24 juillet 2012, par Itai Sagi

  I'm using ffmpeg to convert videos on the fly, as they say, and I'm facing with a very annoying, unsolvable and unreferenced problem (as of yet ;) ), when I run my php script, it basically works - takes the file, uses ffmpeg, starts converting it, but halway through it's finished, the browser hangs, I don't understand why or how to resolve it :
  (even with set_time_limit the bastard won't work).

  function convertToMp4(){
  
      /*
  
       * Converts a file to mp4, returns the new file name
  
       */
  
      set_time_limit(0);
  
      $tmpFile = $this->fileName;
  
      $newFile = uniqid();
  
      $outputFile = "output/$justFile.mp4";
  
      exec("ffmpeg -i " . $tmpFile . " -acodec copy -ar 44100 -ab 96k " . $outputFile. " &");
  
      unlink($tmpFile);
  
      return $outputFile;
  
  }

  Ideas ?