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• Add text to video using FFMPEG(c# application)

  3 février 2020, par uzura

  Trying to add text to video using FFMPEG via c# script using the following command

  ffmpeg -i input.mp4 -vf drawtext="\text='Stack Overflow': fontcolor=white: fontsize=24: box=1: boxcolor=black@0.5: x=w-tw-10:y=h-th-10" -codec:a copy output.mp4

  This works when run it from cmd but when I implement it here :

      public void AddNewLabel(string label)
  
      {
  
          //string video = "input.mp4";
  
          string filter = "input.mp4 -vf drawtext=\"\text='sampletext': fontcolor=white: fontsize=24: box=1: boxcolor=black: x=w-tw-10:y=h-th-10\"";//problemm is this line
  
  
  
          string args = $"/c ffmpeg -i {filter} -codec:a copy output.mp4";
  
  
  
          ProcessStartInfo startInfo = new ProcessStartInfo
  
          {
  
              CreateNoWindow = false,
  
              FileName = "cmd.exe",
  
              WorkingDirectory = outputpath,
  
              Arguments = args
  
          };
  
  
  
          using (Process exeProcess = Process.Start(startInfo))
  
          {
  
              exeProcess.WaitForExit();
  
          }
  
      }

  The output is a 0kb mp4 file that cant be opened. When i remove everything after input.mp4 in filter, the output is fine. What could I be doing wrong ?

• FFMPEG blending comes out looking grayscale rather than colourful

  17 novembre 2022, par OneWorld

  When i do a blend of two pngs, it comes out looking grayscale whereas it should have colour.

  


  These are the two PNG input assets that I then create MP4s from :-

  


  

  


  

  


  Here is the command :-

  


  ffmpeg -i black_circle.png -i pikachu.png -filter_complex "[0:v]setsar=sar=1,format=rgb24[rgb1];[1:v]setsar=sar=1,format=rgb24[rgb2];[rgb1]split[out1_1][out1_2];[out1_1]crop=50:50:0:0:exact=1,setsar=1[cropped1];[cropped1][rgb2]blend=screen[blended1];[out1_2][blended1]overlay=0:0" pikachu_screened_on_circle_rgb.png


  


  And here is the output :-

  


  

  


  However, Pikachu should retain his Red, Green and Blue, but instead Pikachu looks grayscale.

  


  I was wondering why this is ?

  


  And what i need to do so that Pikachu retains his yellow skin, and rosey cheeks ?

  


  So I thought initially that it might be something to do with the white and black circle being a grayscale asset. But then I replaced the black and white circle with this asset :-

  


  

  


  and I saw that when something is black FFMPEG makes it grayscale :-

  


  

  


  The command using these two assets instead is this :-

  


  ffmpeg -i rgb_backing.png -i pikachu.png -filter_complex "[0:v]setsar=sar=1,format=rgb24[rgb1];[1:v]setsar=sar=1,format=rgb24[rgb2];[rgb1]split[out1_1][out1_2];[out1_1]crop=50:50:0:0:exact=1,setsar=1[cropped1];[cropped1][rgb2]blend=screen[blended1];[out1_2][blended1]overlay=0:0" pikachu_screened_on_rgb_backing.png


  


  Is there a way to invert black to white in FFMPEG ?

  


• Revision 35682 : maj invalideur

  28 février 2010, par brunobergot@… — Log

  maj invalideur