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• ffmpeg How does the blend filter work

  8 juin 2018, par tainguyen

  I have small project which uses blend filter of FFmpeg library.

  I read the examples of this document
  https://ffmpeg.org/ffmpeg-filters.html#blend_002c-tblend

  But I’m not clearly understand about it.

  X, Y : the coordinates of the current sample

  W, H : the width and height of currently filtered plane

  What are the sample and filtered plane ?
  Is there any document about these things.

• php ffmpeg thumbnail size won't work

  26 septembre 2017, par Rtra

  In my code I am trying to generate a thumbnail in fixed size from a local hosted videos using ffmpeg but when I put my $default_size variable in command it won’t generate thumbnails I don’t know what I am doing wrong in it.

  Here is my PHP code

  <?php
  
  $default_size = '320x240';
  
  $result_generator = shell_exec("ffmpeg -i $video -deinterlace -an -ss $half -t $half -r 1 -y -vcodec mjpeg -f mjpeg $default_size $thumbnail 2>&1");
  
  if( ! $result_generator) {
  
  throw new Exception('Error creating video thumbnail');
  
  }
  
  print $result_generator . "\n\n";
  
  ?>

• To get OpenCV VideoWriter work across platforms consistently for MP4 container with H264 encoding

  28 mars 2019, par Moh

  I am trying to get OpenCV VideoWriter work across platform consistently for MP4 container with H246 encoding.

  Target platforms in order of importance - Ubuntu, Raspbian, OSX

  Basically, my shortcoming at this point is not understanding the relationship of FourCC code (as a parameter to OpenCV VideoWriter) to the FFMPEG backend and its requirements. I am interested to understand the game in play rather than discussing a piece of code.

  What I want to know is when I specify ’X264’ as FourCC code trying to write an x.MP4 file (FFMPEG backend) and the request is marshalled to FFMPEG what requirements/dependencies need to be satisfied by the OS for it to success.

  So far I have got my python stack writing MP4 video files across Raspbian/Ubuntu/OSX, with a hack.

  On my Raspbian stretch installation, I use 0x00000021 as the fourCC code.
  On Ubuntu (VM on OSX) and on OSX, AVC1 works.

  Days of Googling only delivered those hacks, not a good understanding of the problem.

  The x264 as FourCC code leads to one of - failure, non-portable video file + annoying FFMPEG warning.

  I am trying to get to the bottom of it.

  The code,

      #self.__fourCC = cv2.VideoWriter_fourcc('x', '2', '6', '4')
  
      self.__fourCC = cv2.VideoWriter_fourcc('a', 'v', 'c', '1')
  
      if PlatformUtils.isRunningOnRaspberryPi():
  
          self.__fourCC = 0x00000021

  I have control over the version both OpenCV and FFMPEG (if required GStreamer too). I can and have built them for Ubuntu/Raspbian.