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• Fast seeking ffmpeg multiple times for screenshots

  14 septembre 2021, par user3786834

  I have come across https://askubuntu.com/questions/377579/ffmpeg-output-screenshot-gallery/377630#377630, it's perfect. That has done exactly what I wanted.

  



  However, I'm using remote URLs to generate the screenshot timeline. I do know it's possible to fast seek with remote files using https://trac.ffmpeg.org/wiki/Seeking%20with%20FFmpeg (using -ss before the -i) but this only runs the once.

  



  I'm looking for a way to use the

  



  ./ffmpeg -i input -vf "select=gt(scene\,0.4),scale=160:-1,tile,scale=600:-1" \
-frames:v 1 -qscale:v 3 preview.jpg


  



  command but using the fast seek method as it's currently very slow when used with a remote file. I use PHP but I am aware that a C method exists by using av_seek_frame, I barely know C so I'm unable to implement this into a PHP script I'm writing. So hopefully, it is possible to do this directly with ffmpeg in the PHP system() function.

  



  Currently, I run seperate ffmpeg commands (with the -ss method) and then combine the screenshots together in PHP. However, with this method it will be refetching the metadata each time and a more optimized method would be to have it all happen in the same command line because I want to reduce the amount of requests made to the remote url so I can run more scripts in sequence with each other.

  



  Thank you for your help.

  


• Applying same filter_complex many times before output [duplicate]

  19 août 2019, par Fabián

  This question already has an answer here :

  • FFmpeg command to apply multiple filters and limit the final file size [closed]
    
    1 answer
    
  • Applying multiple filters at once with FFMPEG
    
    2 answers
    
  • FFMpeg - Combine multiple filter_complex and overlay functions
    
    1 answer
    
  • ffmpeg : multiple video filter order issue
    
    1 answer
    

  It’s not a duplicate. This is about using filter_complex, not -vf.

  In my video there’s an object that has shades of yellow (more orange-like) and a solid yellow as background.

  I need to output all frames into a png sequence, using a color key filter to replace the yellow from the background :

  ffmpeg -ss 4 -i original.mp4 -t 2 -filter_complex "[0:v]colorkey=0xfff31b:0.125:0[ckout]" -map "[ckout]" colorkey-%d.png

  This removes the specific color, but leaves some pints behind, and some items are yellow-themed, so blending value is a no-no for this scenario.

  I need to get rid of 4 specific yellow-colors from the frames : 0xfff31b, 0xfae56b, 0xfaec46 and 0xeee2a0, and I plan to run the same filter for specific colors before getting the final result.

  So first I tried this :

  ffmpeg -ss 4 -i original.mp4 -t 2 -filter_complex "[0:v]colorkey=0xfff31b:0.4:0[ckout1];[0:v]colorkey=0xfae56b:0.4:0[ckout2];[0:v]colorkey=0xfaec46:0.4:0[ckout3];[0:v]colorkey=0xeee2a0:0.4:0[ckout4]" -map "[ckout4]" colorkeyrefined-%d.png

  Then this :

  ffmpeg -ss 4 -i original.mp4 -t 2 -filter_complex "[0:v]colorkey=0xfff31b:0.4:0[ckout]" -filter_complex "[0:v]colorkey=0xfae56b:0.4:0[ckout]" -filter_complex "[0:v]colorkey=0xfaec46:0.4:0[ckout]" -filter_complex "[0:v]colorkey=0xeee2a0:0.4:0[ckout]" -map "[ckout]" colorkeyrefined-%d.png

  But both display the same error :

  Filter colorkey has an unconnected output.

  Is there a way to apply the colorkey feature 4 times (with the mentioned values) in one go ?

• Applying the same filter many times before output [duplicate]

  19 août 2019, par Fabián

  This question already has an answer here :

  • FFmpeg command to apply multiple filters and limit the final file size [closed]
    
    1 answer
    

  In my video there’s an object that has shades of yellow (more orange-like) and has a solid yellow as background.
  I need to output all frames into a png sequence, using a color key filter to replace the yellow from the background :

  ffmpeg -ss 4 -i original.mp4 -t 2 -filter_complex "[0:v]colorkey=0xfff31b:0.125:0[ckout]" -map "[ckout]" colorkey-%d.png

  This removes all the yellow background. However, it leaves some pints of yellow behind, and some items are yellow-themed, so blending isn’t an option for this scenario.

  In the end I need to get rid of 4 specific yellow-colors from the frames : 0xfff31b, 0xfae56b, 0xfaec46 and 0xeee2a0. My idea is to run the same filter for every color.

  So first I tried this :

  ffmpeg -ss 4 -i original.mp4 -t 2 -filter_complex "[0:v]colorkey=0xfff31b:0.4:0[ckout1];[0:v]colorkey=0xfae56b:0.4:0[ckout2];[0:v]colorkey=0xfaec46:0.4:0[ckout3];[0:v]colorkey=0xeee2a0:0.4:0[ckout4]" -map "[ckout4]" colorkeyrefined-%d.png

  Then this :

  ffmpeg -ss 4 -i original.mp4 -t 2 -filter_complex "[0:v]colorkey=0xfff31b:0.4:0[ckout]" -filter_complex "[0:v]colorkey=0xfae56b:0.4:0[ckout]" -filter_complex "[0:v]colorkey=0xfaec46:0.4:0[ckout]" -filter_complex "[0:v]colorkey=0xeee2a0:0.4:0[ckout]" -map "[ckout]" colorkeyrefined-%d.png

  But both display the same error :

  Filter colorkey has an unconnected output.

  Is there a way to apply the colorkey 4 times (with the mentioned values) in one go ?