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• FFMPEG - concatenation of a dynamic number of files with different codecs

  15 septembre 2020, par timrodenbroeker

  I am trying to write a bash-script for FFMPEG that concatenates a dynamic number of video-files with different codecs.

  


  This is what i have right now : The script basically does the job and concatenates 3 videos.

  


  ffmpeg -i 1.mp4 -i 2.mp4 -i 3.mp4 \
    -filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a] concat=n=3:v=1:a=1 [v] [a]" \
    -map "[v]" -map "[a]" out.mp4


  


  But as mentioned i would like to write a script which can process a dynamic number of video-files.

  


  For this purpose i have created a text file that contains all the source-material.

  


  file './lib/intro.mp4'
file './temp/1.mp4'
file './temp/2.mp4'
file './temp/3.mp4'
file './lib/outro.mp4'


  


  I know that i can easily pass a text-file to the -i parameter. The problem is that it the -filter_complex-parameter is not dynamic. The number of files is fixed here.

  


  ffmpeg -i files.txt \
    -filter_complex "[0:v] [0:a] [1:v] [1:a] [2:v] [2:a] concat=n=3:v=1:a=1 [v] [a]" \ 
    -map "[v]" -map "[a]" out.mp4


  


  Is it possible to modify the script to concatenate a dynamic amount of video-files ?

  


  Thanks in advance !

  


• Revision 3606b78108 : Modified test for auto key frame detection. The existing test was triggering a

  16 avril 2015, par paulwilkins

  Changed Paths :
   Modify /vp9/encoder/vp9_firstpass.c

  
  
  Modified test for auto key frame detection.

  The existing test was triggering a lot of false positives on some types
  of animated material with very plain backgrounds. These were triggering
  code designed to catch key frames in letter box format clips.

  This patch tightens up the criteria and imposes a minimum requirement
  on the % blocks coded intra in the first pass and the ratio between the
  % coded intra and the modified inter % after discounting neutral (flat)
  blocks that are coded equally well either way.

  On a particular problem animation clip this change eliminated a large
  number of false positives including some cases where the old code
  selected kf several times in a row. Marginal false negatives are less
  damaging typically to compression and in the problem clip there are now
  a couple of cases where "visual" scene cuts are ignored because of well
  correlated content across the scene cut.

  Replaced some magic numbers related to this with #defines and added
  explanatory comments.

  Change-Id : Ia3d304ac60eb7e4323e3817eaf83b4752cd63ecf

• Is it possible to split frame accurate an AAC file using FFmpeg ?

  12 mai 2019, par CAHbKA

  What I did :

  # create source material
  
  ffmpeg -y -i some.file -c:a libfdk_aac -profile:a aac_he -b:a 128k -ar 44100 source.m4a
  
  
  
  # split into two parts 
  
  ffmpeg -y -ss 00:00:00 -i source.m4a -to 6 -c copy part1.m4a
  
  ffmpeg -y -ss 00:00:06 -i source.m4a -c copy part2.m4a
  
  
  
  # re-encode only the first part with the same setting as source file
  
  fmpeg -y -i part1.m4a -c:a libfdk_aac -profile:a aac_he -b:a 128k -ar 44100 part1reencoded.m4a
  
  
  
  # create file list to be concatenated
  
  echo 'ffconcat version 1.0
  
  file part1reencoded.m4a
  
  file part2.m4a' > my.list
  
  
  
  # finally concatenate both parts
  
  ffmpeg -y -f concat -safe 0 -i my.list -c copy parts.m4a
  
  
  
  # play the result
  
  ffplay parts.m4a

  Unfortunately, the result file has noises at 00:00:06.

  Is it possible to split frame accurate an AAC file using FFmpeg ?