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• python3 openCV VideoCapture only black image (Raspbian Stretch)

  21 juin 2018, par PrimuS

  I have a little python function that analyzes a video, chunks it into one image per second and gives me the most dominant color for that image. (Code can be found here : https://github.com/primus852/python-movie-barcode)

  This works great on my Windows testing environment. However, on my Rasbian Stretch Raspberry Pi Setup it only produces a black image, as the source seems to be black.

  I compiled OpenCV (3.4.1) myself with this great article : https://www.pyimagesearch.com/2017/09/04/raspbian-stretch-install-opencv-3-python-on-your-raspberry-pi/, and it worked perfectly fine. I am using python3 and a virtualenv.

  I tried adding the ffmpeg package : apt install ffmpeg, to no avail.

  2 ideas

  • I compiled the openCV source without support for mkv/mp4/similar ? If so, how would I check that and can I just "re-compile" the whole package ?
  • I am missing codecs, where would I be able to check that ?

  The crucial code (I think) is this :

  cap = cv2.VideoCapture(full_path) are there other options that do not break the majority of my code ? I read about skvideo.io from scikit-video but that does not seem to work with my code...

  I am new to python, any hint is appreciated

  // EDIT, I think it is not a duplicate because I pass the I get no error that the capture cannot be opened and :

  OpenCV FFMPEG support :

  • python -c "import cv2; print(cv2.getBuildInformation())" | grep -i ffmpeg
    • returns : FFMPEG: YES

  FFMPEG Codec :

  • ffmpeg -codecs | grep -i avc (file is using AVC)
    • returns : DEV.LS h264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (decoders: h264 h264_mmal h264_vdpau ) (encoders: libx264 libx264rgb h264_omx h264_vaapi )

  File PATH

  It exists and the path is correct...

  Any other ideas ? Could it possibly the virtualenv ?

  //EDIT2

  Tried with an AVI file

  works...

• sh : /usr/bin/ffmpeg : not found

  22 janvier 2016, par Rio

  I’m trying to execute ffmpeg from PHP using shell_exec or exec but it fails. Why can this be ? The command /usr/bin/ffmpeg works from the terminal, so I tried

  <?php
  
  $cmd = "/usr/bin/ffmpeg";
  
  exec($cmd." 2>&1", $out, $ret);
  
  if ($ret){
  
      echo "There was a problem!\n";
  
      print_r($out);
  
  }else{
  
      echo "Everything went better than expected!\n";
  
  }
  
  ?>

  and I keep on getting

  There was a problem! Array ( [0] => sh: /usr/bin/ffmpeg: not found )

  Any help would be greatly appreciated.

  Permission on the executable are

  -rwxr-xr-x  1 root   root      106552 Jun 12 09:53 ffmpeg

  Running which /usr/local/bin/ffmpeg into $cmd returns an empty Array.

• How to compile ffmpeg and x264 with thread support for android ?

  18 mai 2017, par Sureshkumar Menon

  i want to compile both x264 and ffmpeg with thread support for ANDROID .FFmpeg and x264 didn’t compile with thread support even after enabling enable-pthreads and enable-threads respectively.

  Both the config.h contains #define HAVE_THREAD 0 and #define HAVE_PTHREADS 0

  1.How to compile with thread support.
  2.Second question is that when i increase the gop size from 1 to some other value encoder returns 0 for certain subsequent frames.This causes a delay more than 3 to 5 seconds in vide playing