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• How to add delay to only one audio file in an mp4 file containing many language sounds with ffmpeg ?

  10 décembre 2023, par Mesut

  I have an mp4 movie file. It contains audio files of two different languages. Audio #0 and Audio #1. The codec of both sounds is AAC. Now I only want to give 2000ms delay to Audio #1 audio file. I do this with ffmpeg and add the delay successfully, the command I give below adds delay to both sounds. I only want to delay Audio #1. After doing this, I want to get an output containing all sounds and subtitles without re-encoding. I just couldn't achieve this. Does anyone know how I can do this ?

  


  ffmpeg -i "input_movie.mp4" -itsoffset 2000ms -i "input_movie.mp4" -map 1:v -map 0:a -map 0:s -c copy "Output_movie.mp4"
This command adds delay to all streams, I don't want that.

  


  ffmpeg -i "input_movie.mp4" -itsoffset 2000ms -i "input_movie.mp4" -map 1:v -map 0:a:1 -map 0:s -c copy "Output_movie.mp4"
In the command line above, this time it adds delay only to audio file #1, but this time it does not include other audio files in the output mp4 file.

  


• Can´t convert .mp4 file to .mjpeg file with ffmpeg

  19 février 2018, par Herr HupfDohle

  I use ffmpeg to convert a .mp4 file to a .mjpeg file and I fail doing so.
  What i tried so far :
  Converting directly from .mp4 to .mjpeg with one of these :

      "ffmpeg -i input.mp4 output.mjpeg"
  
      "ffmpeg -i input.mp4 -framerate 25 output.mjpeg"

  Getting all the individual images of my video (which worked fine) and put them together to a .mjpeg file did not work as well.

      "ffmpeg -i input.mp4 image%d.jpeg"
  
      "ffmpeg -f image2 -i image%d.jpeg output.mjpeg", or
  
      "ffmpeg -f image2 -i image%d.jpeg -framerate 25 output.mjpeg"

  "Solutions" like the following one did not work, cause I need a file extension .mjpeg so -c:v mjpeg is not enough cause I end up with sth. like .mov !

  "ffmpeg -i input.mov -c:v mjpeg -q:v 3 -huffman optimal -an output.mov"

  To view my files I use vlc player.

  I always end up with a .mjpeg file which has the length of 10 seconds and only shows the very first image of my 4000 pictures.

• subprocess.py returns a File Not Found error

  7 avril 2021, par wasneeplus

  As part of a video analysis script I wanted to find the duration of a video file. For this I found the script offered in the first answer to this question : How to get the duration of a video in Python ?

  


  import subprocess

def get_length(filename):
    result = subprocess.run(["ffprobe", "-v", "error", "-show_entries",
                             "format=duration", "-of",
                             "default=noprint_wrappers=1:nokey=1", filename],
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT)
    return float(result.stdout)


  


  This code works fine when my friend runs it in a Jupyter server environment, but when I try it on my laptop the trouble starts.

  


  When I imput the following filename into the function :

  


  filename = "C:\\Users\\benja\\OneDrive - De Haagse Hogeschool\\Onderzoeken 3\\8V.mp4"


  


  I get the following error :

  


      Traceback (most recent call last):&#xA;  File "c:/Users/benja/OneDrive - De Haagse Hogeschool/Onderzoeken 3/python_script.py", line 9, in <module>&#xA;    num_of_frames = math.floor((pf.get_length(filename) - 1)) * 30&#xA;  File "c:\Users\benja\OneDrive - De Haagse Hogeschool\Onderzoeken 3\python_funcs.py", line 21, in get_length&#xA;    stderr=subprocess.STDOUT)&#xA;  File "C:\Users\benja\Anaconda3\lib\subprocess.py", line 466, in run&#xA;    with Popen(*popenargs, **kwargs) as process:&#xA;  File "C:\Users\benja\Anaconda3\lib\subprocess.py", line 769, in __init__&#xA;    restore_signals, start_new_session)&#xA;  File "C:\Users\benja\Anaconda3\lib\subprocess.py", line 1172, in _execute_child&#xA;    startupinfo)&#xA;FileNotFoundError: [WinError 2] Het systeem kan het opgegeven bestand niet vinden&#xA;</module>

  


  I do realise that my problem is almost identical to that of several other questions on here. However, their solutions don't seem to work for me. I have tried to :

  


  

  • Add the location of ffmpeg-win64-4.2.2.exe to the Path system variable.

  


  • Add the location of python.exe to the ComSpec system variable.

  


  • Put the videofile in the same directory as the script.

  


  


  I would be most grateful if someone could point me in the right direction. Thank you in advance.