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• How to efficiently convert images to a video in `ffmpeg`

  9 septembre 2022, par tawfikboujeh

  I discovered squoosh and found out that it does crazy compression on images,

  


  Squoosh only works on images and i wanted to scale it to work on videos.

  


  I then wrote this script to convert the video to a set of images that I'll squoosh and then reconstitute to a video again using the almighty ffmpeg.

  


  mkdir out ; rm -rf ./out/*
ffmpeg -i input.mp4 -r 25 buffer.mp4 # for a reason, i needed to create a buffer, this is hacky, but whatever.
ffmpeg -i buffer.mp4 -vf fps=25 out/out%d.png # convert the image into images
squoosh-cli --mozjpeg '{quality: 75}' out/*.png # compress
FRAMERATE=$(ffmpeg -i buffer.mp4 2>&1 | sed -n "s/.*, \(.*\) fp.*/\1/p") # get the framerate from buffer video
ffmpeg -framerate $FRAMERATE -i out/out%d.jpg output.mp4 # reconstitute the video knowing the framerate and having the compressed images


  


  the images are 90% smaller but the video has a bigger size than the original one.

  


  benchmarks :

  


  for the images :

  


  1.jpeg : 98 KB on disk
1.png : 1,7 MB on disk 


  


  for the videos :

  


  input.mp4 : 20 Mb on disk
buffer.mp4 : 21 Mb on disk
output.mp4 : 19 Mb on disk


  


  Any idea on how to make ffmpeg pack the images to an acceptable size ?

  


• avcodec/cfhddata : Reduce stack usage

  3 septembre 2022, par Andreas Rheinhardt

  avcodec/cfhddata : Reduce stack usage
  Creating CFHD RL VLC tables works by first extending
  
  the codes by the sign, followed by creating a VLC,
  
  followed by deriving the RL VLC from this VLC (which
  
  is then discarded). Extending the codes uses stack arrays.
  The tables used to initialize the VLC are already sorted
  
  from left-to-right in the tree. This means that the
  
  corresponding VLC entries are generally also ascending,
  
  but not always : Entries from subtables always follow
  
  the corresponding main table although it is possible
  
  for the right-most node to fit into the main table.
  This suggests that one can try to use the final destination
  
  buffer as scratch buffer for the tables with sign included.
  
  Unfortunately it works for neither of the tables if one
  
  uses the right-most part of the RL VLC buffer as scratch buffer ;
  
  using the left-most part of the RL VLC buffer as scratch buffer
  
  might work if one traverses the VLC entries from end to start.
  
  But it works only for the little RL VLC (table 9), not for table 18.
  Therefore this patch uses the RL VLC buffer for table 9
  
  as scratch buffer for creating the bigger table 18.
  
  Afterwards the left part of the buffer for table 9 is
  
  used as scratch buffer to create table 9.
  This fixes the cfhd part of ticket #9399 (if it is not already fixed).
  
  Notice that I do not consider the previous stack usage excessive.
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/cfhddata.c

• FFMPEG weight/compression compromise

  15 juillet 2022, par untrimattacks

  I'm look for the best way to reduce the weight of videos. Find a weight/compression compromise on different resolutions (from 480p to 1080p). But without degrading the audio/video quality too much.

  


  I've looked at different questions/answers and looking the FFMPEG documentation but I'm not sure about the best way to do this

  


  maybe

  


  


  ffmpeg5\ffmpeg.exe -i "file.mp4" -i watermark.png -filter_complex
"overlay=x=(main_w-overlay_w)*0.95:y=(main_h-overlay_h)*0.95"
-loglevel error -stats -hwaccel cuda -preset veryfast "fileEDIT.mp4"

  


  


  or

  


  


  ffmpeg5\ffmpeg.exe -loglevel error -stats -hwaccel cuda -i "file.mp4" -i watermark.png -filter_complex
"overlay=x=(main_w-overlay_w)*0.95:y=(main_h-overlay_h)*0.95" -vcodec
libx265 -crf 21 "fileEDIT.mp4"

  


  


  or

  


  


  ffmpeg5\ffmpeg.exe -loglevel error -stats -hwaccel cuda -i "file.mp4"
-i watermark.png -filter_complex "overlay=x=(main_w-overlay_w)*0.95:y=(main_h-overlay_h)*0.95" -vcodec
libx265 -crf 21 -maxrate 3200k -bufsize 4200k "fileEDIT.mp4"

  


  


  (i add an overlay and this overlay size is different depending on the resolution, it's smaller or bigger but that's another concern. I have to look but i have an idea how to do it with GetDetailsOf method, iColumn 314 )

  


  thanks