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• FFmpeg - Change resolution of the video with aspect ratio

  18 septembre 2024, par Arthur

  all.

  



  How to change resolution of the video with aspect ratio with FFmpeg ?

  



  There are options 
http://manpages.ubuntu.com/manpages/oneiric/man1/ffmpeg.1.html

  



         -s size
       Set frame size. The format is wxh (ffserver default = 160x128,
       ffmpeg default = same as source).  The following abbreviations are
       recognized:


  



  and

  



         -aspect aspect
       Set the video display aspect ratio specified by aspect.

       aspect can be a floating point number string, or a string of the
       form num:den, where num and den are the numerator and denominator
       of the aspect ratio. For example "4:3", "16:9", "1.3333", and
       "1.7777" are valid argument values.


  



  For example, I have two input videos :

  



  

  • with 200*400 resolution

  


  • with 400*700 resolution

  


  



  I need to make output video with 100*200 resolution.

  



  If I will run ffmpeg with -s 100x200, then second video will have bad aspect ratio.

  



  How can I limit output video by width, with auto aspect ratio by height ?

  



  For example, I want specify for the output video only width 100px and ffmpeg must automatically calculate height with right aspect ratio.

  



  For first video it will be :

  



  200/100=2

  



  400/2=200

  



  Ie 100x200

  



  For second video it will be :

  



  400/100=4

  



  700/4=75

  



  Ie 100x75

  



  Is it possible ?

  


• FFMPEG : How to create a webp preview file with 16:9 aspect ratio and no stretching

  22 février 2023, par X 47 48 - IR

  I'm trying to create a webp file for videos to show a quick preview of them like Youtube with 16:9 aspect ratio and black/blurred background.

  


  

  


  How is that possible to make something like this using FFMPEG ?

  


  The following script is what I tried and it works, but when the w / h ratio of the video is smaller than 1.7711442786069651741293532338308... or equal to it, I get this error :

  


  Error :

  


  [Parsed_crop_5 @ 000002438207c580] Invalid too big or non positive size for width '350' or height '196'


  


  ---

  


  FFMPEG script

  


  ffmpeg -r 16 -ss 0 -i <input file="file" /> -loop 0 -c:v libwebp -lavfi "[0:v]scale=ih*16/9:-1,boxblur=luma_radius=min(h\,w)/20:luma_power=1:chroma_radius=min(cw\,ch)/20:chroma_power=1[bg];[bg][0:v]overlay=(W-w)/2:(H-h)/2,setpts=0.3*PTS,scale=350:-1,crop=h=iw*9/16" -vb 800K -t 00:00:03 out.webp -y&#xA;

  


• FFMPEG : How to create a webp preview file with 16:9 aspect ratio without stretching

  30 août 2018, par A - O

  

  How to make something like this by using FFMPEG ?

  I’m trying to create a webp file for videos to show a quick preview of them like Youtube with 16:9 aspect ratio and black/blurred background

  This following script is what I have done and it works, But when the video’s width and height are like this [W:350 H:196] I get this following error.

  Error :

  [Parsed_crop_5 @ 000002438207c580] Invalid too big or non positive size for width '350' or height '196'

  ---

  FFMPEG script

  ffmpeg -r 16 -ss 0 -i <input file="file" /> -loop 0 -c:v libwebp -lavfi "[0:v]scale=ih*16/9:-1,boxblur=luma_radius=min(h\,w)/20:luma_power=1:chroma_radius=min(cw\,ch)/20:chroma_power=1[bg];[bg][0:v]overlay=(W-w)/2:(H-h)/2,setpts=0.3*PTS,scale=350:-1,crop=h=iw*9/16" -vb 800K -t 00:00:03 out.webp -y

  The main problem is this, Ignore other parameters like infinite loop,t, frame rate...

  crop=h=iw*9/16

  In my opinion, some quantities are large floats and that’s why I’m getting this error.