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• A faster way to get screenshots of a video with ffmpeg

  15 juin 2015, par bs7280

  I am trying to use ffmpeg to get screenshots of a video at a given rate, which works exactly as I want, except for the fact that it has to process the entire video (which can take a long time) and use a ton of CPU resources just to grab a few frames.

  Here is the ffmpeg command that I am using to get the screenshots :

  ffmpeg -i "$videoName" -vf fps=$enterFPS img%03d.jpg

  Is there any way to make that faster ?

• How to use ffmpeg commands in heroku

  15 avril 2022, par Alien5516788

  I've created a mp4 to mp3 converter with python using ffmpeg. It works well in my local windows pc. Now I need to host it in heroku as a web app. But the problem is, my app uses usual ffmpeg commands with os module.
for example,

  


  os.system(ffmpeg -i video.mp4 -acodec copy audio.mp3)


  


  So I need to know if tried to run this script in heroku will it work as usual. I'm aware I can use ffmpeg in heroku as a buildpack. But I don't know wheather it works with usual windows ffmpeg commands or not.

  


  I know I can test if it works by deploying my app in heroku, but the app is not completely developed. It has many more features rather than converting videos.
So I need to know this before I further develop this project with usual ffmpeg commands.

  


• Remove Static Pixels from a Video to Mimic a Green Screen Effect [closed]

  2 août 2021, par nKrkan

  I have a video that's 50 seconds in length, resolution of 480x480 and 16 frames per second.

  


  There is a person talking in it, with the background being static I thought if there's a way
  
to remove those static pixels (background) and just extract the moving pixels (foreground)
  
and possibly mimic a green screen effect ?

  


  I was thinking on writing a picture-by-picture comparison tool to do such thing but I don't
  
believe I'm up to the task, or maybe It's laziness.

  


  And now I know, some of you will point out that the video has compression artifacts and that
  
might cause some problems but It doesn't have to be Studio quality stuff.

  


  I tried the ffmpeg command from this question : Remove random background from video using ffmpeg or Python
  
And it does mask the person, but... I couldn't quite get it to work, apparently putting the
  
reference image in the input makes that image burned into the video, thus having no way to
  
remove it, but it did mask the background as black and the person as greenish, so still not a
  
viable way to do it.

  


  Have also tried some Python projects I've found on the GitHub but none of them worked as
  
I expected.

  


  So, what I thought to do is simply compare the first and the second frame of the video, check
  
all the pixels by comparing them with the two sources, and change those that stay within a
  
certain range of the initial pixel value.

  


  I should point out I'm not very knowledgeable with mathematics and the majority of the
  
methods used in these type of things, but perhaps someone could point me to an interesting
  
source to read and learn, or by providing an alternative to the methods aforementioned above.