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• How can I simply do color interpolation on this image and then save the image ? With RGBA channels as example

  24 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 this one 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

  


• Encode audio and video in same format and then merge

  12 août 2012, par ZafarYousafi

  I am using ffmpeg to create videos from images and mkvmerge to then merge these videos in a single video. I now found myself in a situation where I need to merge a video clip(with or without sound) in between these slides. Problem is if video clip has sound then mkvmerge is unable to merge the files since other slides don't have sound. I then decided to generate slide videos with silent sound( I created a silent sound mp3 file and use it when creating video from image). Now another problem arises which occurs when video clip does not have mp3 sound. In this case mkvmerge fails again and complaining about differnt audio format. I need help for ffmpeg command which converts all video parts in same audio and video format so I can use mkvmerge easily to merge the videos or mkvmerge command which allows me to merge files having different audio codec.

  thanx

• FFMPEG disjoin/separating/uncoupling of MP3 album file

  16 mai 2022, par SacDeb

  I have an single MP3 album file that has when loaded in a player multiple tracks with artist and title.

  


  In FFMPEG there is an option to concatenate media files. What I'm looking for is to split this into separate tracks with the title and artist metadata if possible.

  


  So far I was only able to find this option in Audacity which requires manually splitting each segment. Sadly this album doesn't have enough silent parts between tracks.

  


  I wonder since FFMPEG has this option surely there should be an option to do the opposite ?