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• How can we use ffmpeg or fluent-ffmpeg with angular cli ?

  25 juillet 2019, par Nileshdeora1122

  How to use ffmpeg with angular2+ application ?

  im tring to use ffmpeg inside my angular application but it is throwing some error during importing ffmpeg in angular like this :

  // import * as ffmpeg from 'fluent-ffmpeg';

  but getting errors like this :

  ERROR in ./node_modules/fluent-ffmpeg/lib/ffprobe.js
  
  Module not found: Error: Can't resolve 'child_process' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/utils.js
  
  Module not found: Error: Can't resolve 'child_process' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/processor.js
  
  Module not found: Error: Can't resolve 'child_process' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/processor.js
  
  Module not found: Error: Can't resolve 'fs' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/capabilities.js
  
  Module not found: Error: Can't resolve 'fs' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/recipes.js
  
  Module not found: Error: Can't resolve 'fs' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/isexe/mode.js
  
  Module not found: Error: Can't resolve 'fs' in '/home/pfacode1/angularApplication/careerfable2/node_modules/isexe'
  
  ERROR in ./node_modules/isexe/windows.js
  
  Module not found: Error: Can't resolve 'fs' in '/home/pfacode1/angularApplication/careerfable2/node_modules/isexe'
  
  ERROR in ./node_modules/isexe/index.js
  
  Module not found: Error: Can't resolve 'fs' in '/home/pfacode1/angularApplication/careerfable2/node_modules/isexe'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/utils.js
  
  Module not found: Error: Can't resolve 'os' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/recipes.js
  
  Module not found: Error: Can't resolve 'path' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/processor.js
  
  Module not found: Error: Can't resolve 'path' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/capabilities.js
  
  Module not found: Error: Can't resolve 'path' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/fluent-ffmpeg.js
  
  Module not found: Error: Can't resolve 'path' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/options/misc.js
  
  Module not found: Error: Can't resolve 'path' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib/options'
  
  ERROR in ./node_modules/which/which.js
  
  Module not found: Error: Can't resolve 'path' in '/home/pfacode1/angularApplication/careerfable2/node_modules/which'
  
  ERROR in ./node_modules/fluent-ffmpeg/lib/recipes.js
  
  Module not found: Error: Can't resolve 'stream' in '/home/pfacode1/angularApplication/careerfable2/node_modules/fluent-ffmpeg/lib'

• Extract frames from a video results in abnormaly more frames for each fps by using ffmpeg

  15 juin 2021, par alanzzz

  I have a job of using ffmpeg to extract the frames averagely from a video, with different fps. I use this command for it.

  


  ffmpeg -i input.mp4 -r specified_fps -q:v 2 image %4d.png

  


  And I have 3 questions about this task.

  


  

  1. What I expect is that if I double the fps, the number of extracted frames will also get doubled. However, that's not the case. Take one of the input videos as an example. I get 2 extra frames for all the sample factors (80 / 158 / 236 / 392 v.s. 78 / 156 / 234 / 390). Does it related to the mechanism of picking/dropping frames when extracting frames from a video？ (credit to @Tom Yan)

  


  


  video info

  


  

  • Duration : 1min18s

  


  • Frame rate mode : constant (CFR)

  


  • Frame rate : 30.0 FPS

  


  • Total number of frames : 2340

  


  


  Config setting & results

  


  





  


  


  


  


  


  



  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  


  FPS	Actual num of frames	correct num of frames
  1	80	78
  2	158	156
  3	236	234
  5	392	390

  


  


  


  2. I check for the output images, the extracted frames for different fps are totally different from each other. In other words, for example, the 1st image for fps=1 is not the same as the 1st image for fps=2. Is that legitimate ? And is it possible for me the get some identical images for different fps ?

     


  


  3. The last problem is that for some videos I use, the difference between the 1st and 2nd image is different from the difference between the 2nd and 3rd. While for the remaining images, the differences become average. To be specific, there is only a slight change from 1st to 2nd frame, while for 2nd to 3rd, 3rd to 4th, and so on, the changes are the same, which is normally distributed according to the specified FPS. I am wondering why such a case happens ? Does it relate to the I-frame, B-frame, P-frame, GOP, or IDR ?

     


  


  


  I am new to this field and cannot find some useful info from other places. I've tried my best to describe my questions clearly. Feel free to leave some comments. Any help would do me a great favor. Thanks in advance !

  


• About image opacity

  23 octobre 2013, par Mikko Koppanen — Imagick

  There is a common misconception that Imagick::setImageOpacity() would work to reduce the opacity of the image. However, as the name says the method actually sets the opacity throughout the image and thus affects also transparent areas.

  To demonstrate let’s first look at this image of a red circle on a transparent background :

  

  Now, let’s apply setImageOpacity on the image :

  php

  < view plain text >

  1. < ?php
  2. $im = new Imagick (’red-circle.png’) ;
  3. $im->setImageOpacity (0.5) ;
  4. $im->writeImage (’red-circle-setopacity.png’) ;
  5.  ?>

  

  As we can see from the resulting image the transparent background is affected as well.

  In order to actually reduce the opacity of the opaque parts Imagick::evaluateImage can be used instead :

  php

  < view plain text >

  1. < ?php
  2. $im = new Imagick (’red-circle.png’) ;
  3.  
  4. /* Divide the alpha channel value by 2 */
  5. $im->evaluateImage(Imagick: :EVALUATE_DIVIDE, 2, Imagick: :CHANNEL_ALPHA) ;
  6. $im->writeImage (’red-circle-divide.png’) ;
  7.  ?>

  And here are the results :

  

  As the background is already fully transparent so the divide operation causes no changes to it.

  Similar example is available in the PHP manual http://php.net/imagick.evaluateimage and I added a note to setImageOpacity page as well (at the time of writing it has not synced to documentation mirrors yet).