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• How to extract frame video to images with removing duplicate area pixel

  8 juin 2022, par yuwiek

  Can ffmpeg to extract 1 second frames by auto transparent area that duplicate within that 1 second frames ? ex. 1 second have 24 frames. typical default cinema fps. by default ffmpeg just extract that 24 frames to image even only little movement. in simply i can just drop that frame that look same. but i dont want, i want it that area frames from 24 frames. look same, sequential be transparent, so it can reduce size of output. than later i will construct it back to 1 second frames. by just stack it frame by frame.

  


  for clearly, lets say again 1 second have 24 frames, frame 1 and frame 2. only have different in top left, like a rectangle black area. because of that, frame 2 should only output that rectangle black area. so later i just stack it to reconstruct that 1 second frames. then next one frame 3 will compare again with new stack frame 2 to know which area that different. and make it transparent again in frame 3. so on. look this image https://i.ibb.co/25hcrpB/Untitled.png

  


• FFMPEG -t outputs more length than it should ?

  17 novembre 2019, par Taapo

  When I run this command :

  /usr/bin/ffmpeg -y -f lavfi -i 
  
  "color=color=black@0.0:size=1080x1080,format=rgba,subtitles=../content/test/test.ssa:alpha=1" 
  
  -c:a aac -c:v png -t "00:00:13.4" -threads 0 "../content/test/test.ssa.mov" -stats

  And load the resulting mov file into any video editor, I get the length

  00:00:13:10

  I have a couple of hundredths of milliseconds of black (empty) space at the end of the video. What am I missing here ?

  I’m gonna include the SSA file here, so it’s a bit more clear :

  [Script Info]
  
  ScriptType: v4.00
  
  PlayResX: 960
  
  PlayResY: 540
  
  PlayDepth: 0
  
  Timer: 100.0
  
  
  
  [V4+ Styles]
  
  Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
  
  Style: Default,Arial,24,&H00FFFFFF,&HFF000000,&HFF000000,&HFF000000,-1,0,0,0,100,100,0,0.00,3,0,0,5,100,100,100,1
  
  
  
  Dialogue: 0,00:00:00.00,00:00:13.400,Default,,0,0,0,,Testing

• How can I simply replace the colors using the color masks on this image and then save it ? With RGBA channels as example

  31 août 2020, par karl-police

  So I got this GIF here :

  


  

  


  As you can see, it has Red, Green and Blue in it. And it also has a full transparency in it. This was composed together with FFMPEG out of images that looked exactly like that.

  


   

  


  Then, with FFMPEG I "decomposed" the RGB and Alpha channels using the filter "extractplanes".

  


  The gallery of that, in correct order starting from up to down, can be found here :

  


  https://imgur.com/a/WN0aGuW

  


  I am not sure if this actually helps me or if I'm supposed to decompose them. Because apperantly now, after decomposing them, I'm supposed to modify them, but I'm not really sure how. It's like how do I modify the red channel that only has black and white, so all at the end, will match to the specified HEX color that I want it to be to.

  


   

  


  Now, my question is. How do I exactly make the color changing happen ? Can I do this simply with JavaScript ? Is it possible to do with FFMPEG, if possible without ImageMagicks ? Maybe a programming language where not much installation is needed to do that ?

  


  What I understood is that. These channels basically contain values from 0 to 255 with black and white. I think the "brightness" is that what 0 and 255. So something inbetween, would be like grey.

  


  So basically, like we do (255,0,0) for red. In these channels, if I want red somewhere I need to put one fully white pixel on the red channel and on all the other channels, there has to be a fully black pixel.

  


  That's the concept. Now is the question, how can I do this ?

  


   

  


  At the end I want to make it look like the colors this one has, as example :

  


  

  


  This is from a game. So basically that's how it looks like in the game. And the game files only use these RGBA template sprites.

  


   

  


  I asked a similar question here : How to change colors of an image using RGBA and more channels independently of their color

  


  But somehow, I might didn't seem to explain it that well.

  


   

  


  I made a thing here to test around with things. I guess that's nearly close, but the lines are kinda weird. jsfiddle.net/qsgazubk