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• Normalizing and converting audio to mp3 (using python,ffmpeg and ffmpeg-normalize ?)

  25 octobre 2017, par Boris

  #first attempt - works partially (explained below)   
  
  for file in sorted(os.listdir(pathdes)):
  
         os.chdir(pathdes)  
  
         subprocess.call(['ffmpeg-normalize','-m','-l','-0.1',file])
  
         file = 'normalized-' + file
  
         file = file[:-3] + 'wav'
  
         newfile = file[:-3] + "mp3"
  
         subprocess.call(['ffmpeg', '-i', file,'-b:a','320k', newfile])

  Specifically I am looking to convert all WMA files (hour long) to mp3 within a newly created folder containing only files inside (no folders)
  I have a funny result with this, sometimes all files are converted and sometimes only some of the files ! I do not understand why ! (its 8 files and sometimes only 4 are being processed, sometimes 3, I am confused)

  Also, I know it should be possible to do these 2 processes differently, only calling ffmpeg, here is another attempt, here detecting first the maximum peak and then trying to add that to the volume. this time with no success, this creates a zero-sized mp3 file.

  import os 
  
  import subprocess
  
  
  
  def run_command(command):
  
      p = subprocess.Popen(command,
  
                           stdout=subprocess.PIPE,
  
                           stderr=subprocess.STDOUT)
  
      return iter(p.stdout.readline, b'')
  
  
  
  pathdes = "c:/folder/"   
  
  os.chdir(pathdes)
  
  for file in os.listdir(pathdes):
  
      file2 = file[:-3]
  
      file2 = file2 + "mp3"
  
  
  
      #calls ffmpeg and retrieves max_volume - peak level
  
      command = ['ffmpeg', '-i',file,'-filter:a','volumedetect','-f','null','/dev/null']
  
      m = ''
  
      for line in run_command(command):
  
          s = bytes("max_volume", 'utf-8')
  
          if s in line:
  
              m = line.decode('UTF-8')
  
  
  
      l = 0
  
      for t in m.split():
  
          try:
  
              l =(float(t))
  
          except ValueError:
  
              pass
  
  
  
      l = str(-l) 
  
      subprocess.call(['ffmpeg', '-i', file,'-af','"volume='+l+'dB"','-b:a','320k', file2])

• How to compare audio channel differences with FFmpeg ?

  30 septembre 2021, par Deivedux

  I'm making a little script for myself to quickly go through a large volume of video and audio files to compress audio for extra space, but for extra efficiency, I also don't want to waste space by keeping both channels if they're identical.

  


  My issue is that I don't know how to, let's say, check if their decoded versions are at least a 99.99% match, in which case I'd only encode the left channel into mono.

  


  How would I go about doing this ?

  


• What tool can I use to analyze audio and clip webm files ? [closed]

  14 février, par Phillip Feldman

  I have a bunch of 2-3 hour long podcast webms from Youtube. I want to extract the audio from them, and programmatically analyze things like volume, or who's speaking. I then want to use my analysis to clip the original webms. What tools can I use to do this, and is size of the audio files something that I need to consider ? I know python and have used ffmpeg.