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• 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 ?

  


• 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 filters order rotate scale with overlay

  13 décembre 2017, par Sebastián Márquez Lutfy

  I’m trying to render an image over a video. I use the following command after some research

  ffmpeg -y  -i "my_video.mp4" -i "my_image.jpg" -filter_complex "color=color=blue:size=711x400:rate=25[container];[0:v]scale=w=400:h=400,setpts=expr=PTS-STARTPTS[vidscaled];[container][vidscaled]overlay=eval=init:shortest=1:x=155:y=0[overlay0];[1:v]scale=w=123:h=123,rotate=a=323.7*PI/180:c=black@0:oh='roth(323.7*PI/180)':ow='rotw(323.7*PI/180)':bilinear=1[imgproc];[overlay0][imgproc]overlay=eval=init:x=18:y='237-abs(123*sin(323.7*PI/180))'[overlay1]" -map "[overlay1]" -map 0:a -strict -2 -preset ultrafast -g 120 output.mp4

  The problem with this approach is a low image’s quality since scaling is applied before rotate. So i tried to apply the rotation before scaling, (see next command)

  ffmpeg -y  -i "my_video.mp4" -i "my_image.jpg" -filter_complex "color=color=blue:size=711x400:rate=25[container];[0:v]scale=w=400:h=400,setpts=expr=PTS-STARTPTS[vidscaled];[container][vidscaled]overlay=eval=init:shortest=1:x=155:y=0[overlay0];[1:v]rotate=a=323.7*PI/180:c=black@0:oh='roth(323.7*PI/180)':ow='rotw(323.7*PI/180)':bilinear=1,scale=w=173:h=173[imgproc];[overlay0][imgproc]overlay=eval=init:x=18:y='237-abs(123*sin(323.7*PI/180))'[overlay1]" -map "[overlay1]" -map 0:a -strict -2 -preset ultrafast -g 120 output.mp4

  And the problem : c=black@0 is not working anymore, the bounding box around the rotated image is not transparent.

  Anyone please help this soul.

  pd : Using c=none doesn’t work too, got a green background