docs: def extract_wav(datafile, target=None):
      """ Get LPCM 16bit audio stream from mediafile.
      
          If `target` is a directory, create a .wav with the same basename as the input.
          If target is empty, write to the directory of the source file. Otherwise, use it 
          directly as the target filename.
      """
      if datafile.endswith(".wav"):
          return datafile
  
      target = target or os.path.dirname(datafile) 
      if os.path.isdir(target):
          target = os.path.join(target, os.path.splitext(os.path.basename(datafile))[0] + ".wav")
  
      if datafile.endswith(".flac"):
          cmd = [config.CMD_FLAC, "--silent", "--decode", "--force", "-o", target, datafile]
      else:
          cmd = [config.CMD_FFMPEG, "-v", "0", "-y", "-i", datafile, "-acodec", "pcm_s16le", "-ac", "2", target]
      subprocess.check_call(cmd, stdout=open(os.devnull, "wb"), stderr=subprocess.STDOUT)
  
      return target