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• Changing the background color of the movie while using tpad and adelay

  1er août 2019, par S.T

  i want to change the background color of a movie while using tpad and adelay commands. it is now black ( until the movie starts).

  the command i tried listed below, and i don’t know how to change the color while the movie is in it’s delay ( probably something with the tpad that needs to be change).

   -filter_complex [0:v]scale=1920:1080,tpad=start_duration=5[v];
  
    [0:a]adelay=5s|s[a] -map [v] -map [a] -b 6000k

  the 5 seconds that the movie is in its "waiting mode" needs to be changed from default black to some other color. Thanks.

• Using ffmpeg to print onto video clip actual time and duration from original clip

  24 mai 2023, par Kes

  I am using arch linux and bash and ffmpeg, all are up to date and the latest versions.

  


  I am clipping a video that is 30 seconds long and wish to clip from 5 secs to 10 seconds to a new file, from the original.

  


  In the bottom right hand corner of the clip I wish to show timestamps from the original video as follows

  


  

  • in the 5th second "00:00:05/ 00:00:30"

  


  • in the 6th second "00:00:06/ 00:00:30"
    
etc

  


  • in the 10th second "00:00:10/ 00:00:30"

  


  


  This is an apparentley simple question(?) but the syntax of the command is not at all obvious and I am hoping an expert may shed some light on this.

  


  All I have so far for the drawtext part, which does not do what I want as it only counts the elapsed time from t=0 of the clip, whereas I want it to show the timestamp and total duration of the original clip

  


  drawtext I started with

  


  "drawtext=text='%{pts\:gmtime\:0\:%M\\\\\:%S}':fontsize=24:fontcolor=black:x=(w-text_w-10):y=(h-text_h-10)"


  


  ffmpeg line with drawtext I have started with

  


  ffmpeg -ss 00:00:05 -i  "$in_file" -filter_complex "drawtext=fontfile=font.ttf:text='sample text':x=10:y=10:fontsize=12:fontcolor=white:box=1:boxcolor=black@0.5:boxborderw=5,drawtext=text='%{duration\:hms}':fontsize=12:fontcolor=black:x=(w-text_w-10):y=(h-text_h-10)" -t 5 -c:a copy -c:v libx264 out_file.mp4


  


• How to capture a layered window with transparency background properly ? (using BitBlt)

  25 octobre 2016, par Mitra M

  I want to capture a WPF window (WPF layered window) with transparency background.

  To do that I tried FFmpeg, But :

  1 - If I set AllowTransparency (this is a property of WPF window) to false ,I can capture the window by gdigrab (this is an ffmpeg device), but output has black background.(I don’t want black background)

  2 - If I set AllowTransparency to true then gdigrab won’t work. (get black frame only)

  I have read David’s nice article, he has said :

  if you use BitBlt to do this, you could “or in” the CAPTUREBLT flag if
  you wanted to capture windows that are layered

  The gdigrab uses BitBlt, this is gdigrab.c code snippet :

  /* Blit screen grab */
  
      if (!BitBlt(dest_hdc, 0, 0,
  
                  clip_rect.right - clip_rect.left,
  
                  clip_rect.bottom - clip_rect.top,
  
                  source_hdc,
  
                  clip_rect.left, clip_rect.top, SRCCOPY | CAPTUREBLT)) {
  
          WIN32_API_ERROR("Failed to capture image");
  
          return AVERROR(EIO);
  
      }

  You can see the flags . (SRCCOPY | CAPTUREBLT).

  Please tell me :

  1- Why the gdigrab can not capture a WPF window properly ?

  2 - What changes in this code should be done to do this ?

  (Sorry for my English, I used translate.google)

  Thanks