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• Working with -filter_complex in ffmpeg with a batch concat array

  21 avril 2014, par user3555008

  What I am trying to do here is write an ffmpeg script that takes all songs from a folder and combines them into one audio file using the command line in Windows.

  So far I have

  ffmpeg -i "pathforinput1" -i "pathforinput2" -i "pathforinputn" -filter_complex "[0:0] [1:0] concat=n=(number of songs goes here):v=0:a=1 "[a]"" -map "[a]" -acodec libmp3lame -ab 320k "output file.mp3"

  My problem is that I want to combine it with the existing script :

  for %A in ("input folder\*.extension") do ffmpeg

  to create a total script that uses -i "%A" for the input. The problem I am having here is that each input file requires an entry in the array -filter_complex "[0:0] [1:0] as well as having the total number of input files present in concat=n=(number of files). I’ m willing to use a batch script to make this possible, but I can’t see how I would go about finding the total number of files in a folder and then creating an array for each (for example if there were 7 songs the array would be [0:0] [1:0] [2:0] [3:0] [4:0] [5:0] [6:0]).

  Any help or pointers for making this possible would be great. Someone in this question managed to make something similar for a Unix system but I am using batch files and I don’t know how to modify it for Windows.

  Thanks in advance for any help

  Ok, progress made with the help of the first commenter. However, I think ffmpeg isn’t liking what I’ve made. My code thus far is :

  :: Give you a list of the .wav filenames in -i "filename1" -i "filename2" format
  
  
  
  for %%a in ("C:\Users\James\Input\*.*") do call set var=%%var%% -i "%%a"
  
  echo %var%
  
  
  
  :: Give you the number of .mp3 files
  
  
  
  for /f %%a in ('dir "C:\Users\James\Input\*.*" /b /a-d ^|find /c /v "" ') do set "numfiles=%%a"
  
  echo there are "%numfiles%" files
  
  set /a totalnum=numfiles
  
  
  
  :: dir "C:\Users\James\Input\" /b >> C:\Users\James\Output\filelist.txt
  
  :: print some text
  
  set /a numfiles=numfiles-1
  
  for /L %%b in (0,1,%numfiles%) do call set array=%%array%% [%%b:0]
  
  :: for /L %%b in (0,1,%numfiles%) do call set array=%%array%% [0:0]
  
  echo %array%
  
  for /f "tokens=* delims= " %%C in ('echo %array% ') do set array=%%C
  
  set array=%array:~0,-1%
  
  echo %array%
  
  :: for %%d in ("C:\Users\James\Input\*.*") do ffmpeg -i "%%d" -filter_complex "%array% concat=n=%totalnum%:v=0:a=1 "[a]"" -map "[a]" -acodec libmp3lame -ab 320k "C:\Users\James\Output\outputtestbatch1.mp3"
  
  for %%d in ("C:\Users\James\Input\*.*") do ffmpeg -i "%%d" -filter_complex "%array% concat=n=%totalnum%:v=0:a=1 "[a]"" -map "[a]" -acodec libmp3lame -ab 320k "C:\Users\James\Output\outputtestbatch1.mp3"
  
  pause`

  The issue I am having now is that I think ffmpeg is assuming each input file has audio stream [0:0] rather than incrementing them one after the other. Is there a way to fix this with the input method I’m using ?

  **SECOND EDIT**L : Success ! I modified foxidrive’s script a bit because it was slightly misconfigured. Final product is here :

  @echo off
  
  
  
  for %%a in ("C:\Users\James\Input\*.*") do call set var=%%var%% -i "%%a"
  
  :: echo %var%
  
  :: Give you the number of files
  
  
  
  for /f %%a in ('dir "C:\Users\James\Input\*.*" /b /a-d ^|find /c /v "" ') do set "numfiles=%%a"
  
  echo there are "%numfiles%" files
  
  
  
  for /L %%b in (0,%numfiles%) do call set array=%%array%% [%%b:0]
  
  set array=%array:~1%
  
  echo "%array%"
  
  
  
  ffmpeg %var% -filter_complex "%array% concat=n=%numfiles%:v=0:a=1 "[a]"" -map "[a]" -acodec libmp3lame -ab 320k "C:\Users\James\Output\outputtestbatch1.mp3"
  
  
  
  popd    
  
  pause

• How can I limit the CPU usage of moviepy ?

  11 février 2020, par Egon Kirchof

  Python 3. I am using moviepy to create a new video. The problem is ffmpeg uses 100% of all my cores so I can’t do anything else in the computer.
  There is a parameter for write_videofile called threads but when I adjust it to, say, threads=10 (I have 12 cores in total) there is no difference.
  I even tried invoking the script using cpulimit (cpulimit -l 70 python my_script.py, for instance) but then the script simply doesn’t work, it just freezes, no error message.
  Is there a way I can force moviepy not to use all the cores in the CPU or is there any application (like cpulimit) that would actually work ?

• How can I automate video encoding using FFmpeg

  30 janvier 2020, par park joh

  I want to find the optimal encoding for a video using FFmpeg and looking for a script to automate that.

  there is VMAF (libvmaf) that helps us to measure the quality of the results, I look for a script or a way to use it to decide what is the best flags to encode each video based on libvmaf score.

  For example, I want to get a list of :
  FFmpeg (flag list and values), VMAF score, total size, average bitrate, max bitrate, min bitrate

  Then I would be able to choose the encoding flags based on that list and my bitrate preference.

  Do anyone know how to compose that kind of a script/ direct me to exist one (or existing flag of FFmpeg that I don’t know that do exactly that...)