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• Timestamp information of MP4

  25 juillet 2016, par Zhenjie Zhao

  I want to ask for an easy way to get the timestamp information of a mp4 file. (Sorry that I am not familiar with codec.)

  I am reading the Tobii Pro Glasses SDK document that explains how to synchronize frame with eye tracking data, where they use a terminorlogy called VTS. Goolge cannot find the exact meaning, so I want to ask for what VTS really stands for and how to get it from a mp4 file. Thanks very much !

• FFmpeg WebP vs PNG alpha

  11 août 2022, par Yoz

  Attached x.png and x.webp (webp created from png) have transparent background covered by white X shape.

  


  For some reason FFmpeg scale filter treats the x.png and x.webp differently.
Applying scale filter on the x.webp, causes the output video alpha around the X shape to be premultiplied and so renders with ugly edges.

  


  Following commands, esp. out-webp-scale.png output demonstrates the issue :

  


  

  


  ffmpeg -filter_complex "color=white:200x200[b];movie=x.png,[b]overlay" -y out-png.png

ffmpeg -filter_complex "color=white:200x200[b];movie=x.png,scale=200:200,[b]overlay" -y out-png-scale.png

ffmpeg -filter_complex "color=white:200x200[b];movie=x.webp,[b]overlay" -y out-webp.png

ffmpeg -filter_complex "color=white:200x200[b];movie=x.webp,scale=200:200,[b]overlay" -y out-webp-scale.png


  


  I tried all possible scale filter flags, and also format changing (before and after scale) but no luck to achieve the same result. I am able to un-premultipy the problematic one with unpremultiply filter but I would like to avoid it.

  


  I wonder if there is any workaround for having the same command for both png-s and webp-s

  


  Attachments (please note the completely white image x.png) :

  


  


  


• Multiple Overlay Movies in FFMPEG

  15 décembre 2014, par John Du

  I was trying to make a 3 columns by 2 row overlay in FFMEG

  I found this command which works great for a 2x2 movie overlay

  ffmpeg.exe -i video1.mp4 -i video2.mp4 -i video3.mp4 -i video4.mp4 -filter_complex "[0:0]scale=iw/2:ih/2,pad=iw*2:ih*2[a];[1:0]scale=iw/2:ih/2[b];[2:0]scale=iw/2:ih/2[c];[3:0]scale=iw/2:ih/2[d];[a][b]overlay=w[x];[x][c]overlay=0:h[y];[y][d]overlay=w:h,drawtext=fontsize=12:fontcolor=white:fontfile=/Windows/Fonts/arial.ttf:text='vid1':x=35:y=35,drawtext=fontsize=12:fontcolor=white:fontfile=/Windows/Fonts/arial.ttf:text='vid2':x=(w/2)+35:y=35,drawtext=fontsize=12:fontcolor=white:fontfile=/Windows/Fonts/arial.ttf:text='vid3':x=35:y=(h/2)+35,drawtext=fontsize=12:fontcolor=white:fontfile=/Windows/Fonts/arial.ttf:text='vid4':x=(w/2)+35:y=(h/2)+35" output.mp4

  (Same command just multiple lines only for readability)

  ffmpeg.exe -i video1.mp4 -i video2.mp4 -i video3.mp4 -i video4.mp4 
  
  -filter_complex "[0:0]scale=iw/2:ih/2,pad=iw*2:ih*2[a];[1:0]scale=iw/2:ih/2[b];
  
  [2:0]scale=iw/2:ih/2[c];[3:0]scale=iw/2:ih/2[d];[a][b]overlay=w[x];
  
  [x][c]overlay=0:h[y];[y][d]overlay=w:h,drawtext=fontsize=12:fontcolor=white:
  
  fontfile=/Windows/Fonts/arial.ttf:text='vid1':x=35:y=35,drawtext=fontsize=12:
  
  fontcolor=white:fontfile=/Windows/Fonts/arial.ttf:text='vid2':x=(w/2)+35:y=35,drawtext=fontsize=12:fontcolor=white:
  
   fontfile=/Windows/Fonts/arial.ttf:text='vid3':x=35
  
  :y=(h/2)+35,drawtext=fontsize=12:fontcolor=white:
  
  fontfile=/Windows/Fonts/arial.ttf:text='vid4':x=(w/2)+35:y=(h/2)+35" output.mp4

  I had trouble adding the 2 other movies, I know you add this

  ffmpeg.exe -i video1.mp4 -i video2.mp4 -i video3.mp4 -i video4.mp4 -i video5.mp4 -i video6.mp4

  and this

  -filter_complex "[0:0]scale=iw/2:ih/2,pad=iw*3:ih*2[a];

  but positioning the last 2 movies and text is where I am lost

  image per request [edit]
  of what I want to do in organizing the overlays