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• avcodec/webp : Switch to ff_vlc_init_from_lengths()

  18 avril, par Andreas Rheinhardt

  avcodec/webp : Switch to ff_vlc_init_from_lengths()
  The earlier code would traverse over the code lengths
  
  mutliple times (namely max_length + 1 times - once to get
  
  the maximum length and once for each max_length to assign
  
  codes) before calling ff_vlc_init_sparse() (which may traverse
  
  them twice and sort them). The new code only traverses them once
  
  (+ the one time in ff_vlc_init_from_lengths()).
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/webp.c

• ffmpeg : check videos conformance for dash before concat

  26 janvier 2018, par Massimo Vantaggio

  I wrote a small bash file that reads a folder, generates a playlist, concatenates, adds a logo and encode the big video result for dash ready, i would like to implement it by checking before all videos conformance : if they have same fps, same resolution, same time base etc.
  Below my situation :

  #!/bin/bash
  
  # CONCAT DEMUXER
  
  #This demuxer reads a list of #files and other directives from a text file and demuxes them one after the other, as if #all their packets had been muxed together. All files must have the same streams (same #codecs, same time base, etc.) but can be wrapped in different container formats.
  
  
  
  
  
  
  
  printf "file '%s'\n" *.mp4 > playlist.txt
  
  ffmpeg -auto_convert 1 -f concat -safe 0 -i playlist.txt -c:a aac -b:a 384k -ar 48000 -ac 2 -async 1 -vsync 1 -c:v libx264 -x264opts 'keyint=50:min-keyint=50:no-scenecut' -r 25 -b:v 2400k -maxrate 2400k -bufsize 1200k -vf "scale=-1:432" -vf "movie=stable.png [watermark]; [in][watermark] overlay=main_w-overlay_w-10:10 [out]" out.mp4
  
  clear
  
  echo “VIDEO CONCAT COMPLETED”

  For example below i find this bash that calculate the total duration in second of the videos of the folder, unfortunately I’m unable to put the result into variable.. I’m newbie of bash.

  times=()
  
  for f in *.ts; do
  
      _t=$(ffmpeg -i "$f" 2>&1 | grep "Duration" | grep -o " [0-9:.]*, " | head -n1 | tr ',' ' ' | awk -F: '{ print ($1 * 3600) + ($2 * 60) + $3 }')
  
      times+=("$_t")
  
  done
  
  echo "${times[@]}" | sed 's/ /+/g' | bc

  I wish to check if the videos have the same fps, and same resolution before process, and to get into variable this duration.
  Thanks
  Massimo

• Understanding ffmpeg -benchmark results

  6 septembre 2022, par Ivy Growing

  Adding -benchmark flag to ffmpeg command resutls with addition of following 2 lines in the shell output :

  


  bench: utime=10.125s stime=4.234s rtime=5.606s
bench: maxrss=110080kB


  


  The maxrss serves to indicate the maximum RAM used during the ffmpeg execution. The utime, stime, rtime indicate accordingly :

  


  

  • user time ;

  


  • system time ;

  


  • real time.

  


  


  I tried to understand the meaning of these times from the source code and failed. Please, help.

  


  

  1. Which of these times indicate how much time was human waiting while the ffpmeg was processing the video ?

  


  2. Can this time be seen directly or it's a combination/calculation of these 3 parameters ?

  


  3. How it can be for certain videos utime > rtime and for others utime < rtime ?