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• 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

  


• How to rotate two overlay parallel using FFmpeg

  17 juin 2021, par Pradeep Kumar

  I want to continue rotate two overlay image parallelly depend on the audio length.

  


  I am using below command and it is working fine to create a video and it is rotating the first overlay gif image. but it is not rotating the second textoverlay.png file. I want to rotate both image in the same time.

  


  ffmpeg -loop,1,-i,background.jpg,-ignore_loop,0,-i,overlay1.gif,-i,textoverlay.png,-i,watermark.png,-i,audio.mp3,-filter_complex,[1]scale=524:524,rotate=0.06*PI*t:c=black@0.0:ow='hypot(iw,ih)':oh=ow[b];[2]scale=406:406,rotate=0.06*PI*t:c=black@0.0:ow='hypot(iw,ih)':oh=ow[pic2];[3]scale=100:50[watermark];[0:v][b]overlay=(W-w)/2:(H-h)/2[over1],[over1][pic2]overlay=(W-w)/2:(H-h)/2[pic3],[pic3][watermark]overlay=(W-120):(H-60),scale=830:830,format=yuv420p,-ss,00:00:00,-to,00:00:08,-c:v,mpeg4,-b:a,3M,-c:a,aac,-b:a,192k,-q:v,1,-shortest,output.mp4


  


  I also tried this link But this is not working.
  
Any help would be appreciated.
  
Thanks in advance.

  


• How to find higest bitrate in mp4 file and extract jpg ?

  10 octobre 2018, par Igor Petev

  I im using ffmpeg and have mp4 file that is in size around 50MB and duration 2m7sec.I need to write batch script for windows that will read whole mp4 file find position in seconds where higest bitrate is there and extract jpg image from that position.

  For example, i have mp4 trailer file that i would like to extract cover, using above script where i define time to extract jpg i get on some mp4 trailers black screen...so using above idea to find higet bitrate for shure will not be black screen, will be picture of some scene.

  Here is windows batch code that extract jpg dfrom mp4 using user defined time :

  @ECHO OFF
  
  SET oldName=
  
  SET newName=
  
  
  
  FOR %%A IN (*.mp4) DO (
  
  SET oldName=%%A
  
  SET newName=%%A
  
  CALL :MAKEJPG
  
  )
  
  
  
  :MAKEJPG
  
  SET newName=%newName:mp4=jpg%
  
  IF NOT EXIST %newName% (
  
  START /B /WAIT D:\www\ffmpeg.exe -i "%oldName%" -ss 00:00:17.30 -vcodec mjpeg -vframes 1 -f image2 "%newName%"
  
  EXIT
  
  )