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• libavfilter/scale2ref : Add constants for the primary input

  30 mai 2017, par Kevin Mark

  libavfilter/scale2ref : Add constants for the primary input
  Variables pertaining to the main video are now available when
  
  using the scale2ref filter. This allows, as an example, scaling a
  
  video with another as a reference point while maintaining the
  
  original aspect ratio of the primary/non-reference video.
  Consider the following graph : scale2ref=iw/6 :-1 [main][ref]
  
  This will scale [main] to 1/6 the width of [ref] while maintaining
  
  the aspect ratio. This works well when the AR of [ref] is equal to
  
  the AR of [main] only. What the above filter really does is
  
  maintain the AR of [ref] when scaling [main]. So in all non-same-AR
  
  situations [main] will appear stretched or compressed to conform to
  
  the same AR of the reference video. Without doing this calculation
  
  externally there is no way to scale in reference to another input
  
  while maintaining AR in libavfilter.
  To make this possible, we introduce eight new constants to be used
  
  in the w and h expressions only in the scale2ref filter :
   * main_w/main_h : width/height of the main input video
  
   * main_a : aspect ratio of the main input video
  
   * main_sar : sample aspect ratio of the main input video
  
   * main_dar : display aspect ratio of the main input video
  
   * main_hsub/main_vsub : horiz/vert chroma subsample vals of main
  
   * mdar : a shorthand alias of main_dar
  Of course, not all of these constants are needed for maintaining the
  
  AR, but adding additional constants in line of what is available for
  
  in/out allows for other scaling possibilities I have not imagined.
  So to now scale a video to 1/6 the size of another video using the
  
  width and maintaining its own aspect ratio you can do this :
  scale2ref=iw/6:ow/mdar [main][ref]
  This is ideal for picture-in-picture configurations where you could
  
  have a square or 4:3 video overlaid on a corner of a larger 16:9
  
  feed all while keeping the scaled video in the corner at its correct
  
  aspect ratio and always the same size relative to the larger video.
  I've tried to re-use as much code as possible. I could not find a way
  
  to avoid duplication of the var_names array. It must now be kept in
  
  sync with the other (the normal one and the scale2ref one) for
  
  everything to work which does not seem ideal. For every new variable
  
  introduced/removed into/from the normal scale filter one must be
  
  added/removed to/from the scale2ref version. Suggestions on how to
  
  avoid var_names duplication are welcome.
  var_values has been increased to always be large enough for the
  
  additional scale2ref variables. I do not forsee this being a problem
  
  as the names variable will always be the correct size. From my
  
  understanding of av_expr_parse_and_eval it will stop processing
  
  variables when it runs out of names even though there may be
  
  additional (potentially uninitialized) entries in the values array.
  
  The ideal solution here would be using a variable-length array but
  
  that is unsupported in C90.
  This patch does not remove any functionality and is strictly a
  
  feature patch. There are no API changes. Behavior does not change for
  
  any previously valid inputs.
  The applicable documentation has also been updated.
  Signed-off-by : Kevin Mark <kmark937@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] doc/filters.texi
  • [DH] libavfilter/scale.c

• ffmpeg padding doesn't scale when changing resolution

  5 mars 2023, par Martin

  I have a ffmpeg command which takes a bunch of audio files, 3 image files, and renders a video with them.

  


  Image Input Dimmensions :

  


  

  • 1_front.jpg 600w x 593h

  


  • 2_back.jpg 600w x 466h

  


  • 3_cd.jpg 600w x 598h

  


  


  The video has a resolution of w=600 h=593, which is the resolution of the first img.

  


  Here's the full command

  


  ffmpeg
 -r 2 -i "E:\filepath\10. Deejay Punk-Roc - Knock 'em All The Way Out.aiff"
 -r 2 -i "E:\filepath\11. Deejay Punk-Roc - Spring Break.aiff" -r 2 -i "E:\filepath\12. Deejay Punk-Roc - Fat Gold Chain.aiff" 
 -r 2 -i "E:\filepath\1_front.jpg" -r 2 -i "E:\filepath\2_back.jpg" -r 2 -i "E:\filepath\3_cd.jpg" 
 
 -filter_complex 
 "
 [0:a][1:a][2:a]concat=n=3:v=0:a=1[a]; 
 
 [3:v]scale=w=600:h=593,setsar=1,loop=580.03:580.03[v3]; 

 [4:v]pad=600:593:0:63:color=pink,setsar=1,loop=580.03:580.03[v4];
 
 [5:v]scale=w=600:h=593,setsar=1,loop=580.03:580.03[v5];
 
 [v3][v4][v5]concat=n=3:v=1:a=0,pad=ceil(iw/2)*2:ceil(ih/2)*2[v]"
 
  -map "[v]" -map "[a]" -c:a pcm_s32le -c:v libx264 -bufsize 3M -crf 18 -pix_fmt yuv420p -tune stillimage -t 870.04 
  "E:\filepath\vidOutPutCorrect.mkv"



  


  For filter_complex this second part will add padding to the second image so that it does not get stretched or cropped.

  


  [4:v]pad=600:593:0:63:color=pink,setsar=1,loop=580.03:580.03[v4];


  


  Specifically this part

  


  pad=600:593:0:63:color=pink


  


  Which I understand means w=600 and h=593, but i dont know that the last part 0:63 means.

  


  You can see the output has the pink padding correctly


  


  but i want to render the video with a resolution of w=1920 h=1898 instead of w=600 h=593.

  


  So i update the command to have this new resolution :

  


  ffmpeg -r 2 -i "E:\filepath\10. Deejay Punk-Roc - Knock 'em All The Way Out.aiff" -r 2 -i "E:\filepath\11. Deejay Punk-Roc - Spring Break.aiff" -r 2 -i "E:\filepath\12. Deejay Punk-Roc - Fat Gold Chain.aiff" -r 2 -i "E:\filepath\1_front.jpg" -r 2 -i "E:\filepath\2_back.jpg" -r 2 -i "E:\filepath\3_cd.jpg" 

-filter_complex "
[0:a][1:a][2:a]concat=n=3:v=0:a=1[a];

[3:v]scale=w=1920:h=1898,setsar=1,loop=580.03:580.03[v3];

[4:v]pad=1920:1898:0:63:color=pink,setsar=1,loop=580.03:580.03[v4];

[5:v]scale=w=1920:h=1898,setsar=1,loop=580.03:580.03[v5];

[v3][v4][v5]concat=n=3:v=1:a=0,pad=ceil(iw/2)*2:ceil(ih/2)*2[v]"

 -map "[v]" -map "[a]" -c:a pcm_s32le -c:v libx264 -bufsize 3M -crf 18 -pix_fmt yuv420p -tune stillimage -t 870.04 "E:\filepath\slidet.mkv"


  


  my video does in fact now have a resolution of 1920x1798 which is great, but the 2nd image padding portion has the image super small and in a corner

  


  

  


  So this line works :

  


  pad=600:593:0:63:color=pink


  


  but with a different resolution is looks bad with the image in the top left corner

  


  pad=1920:1898:0:63:color=pink


  


  What do I need to change 0:63 to in order to have the image be centered ?

  


  Download files : http://www.mediafire.com/folder/e8ja1n8elszk1lu,dxw4vglrz7polyh,ojjx6kcqruksv5r,lah9rano4svj46o,q5jg0083vbj9y1p,d3pt8ydf3ulqm5m/shared

  


• Revision 37406 : Le cron toute les minutes Amélioration de pleins de petites choses ...

  18 avril 2010, par kent1@… — Log

  Le cron toute les minutes
  Amélioration de pleins de petites choses
  Incrément mineur de la version