code: def add_media_file(self, input_file, output_file):
          
          if not os.path.exists(input_file):
              raise FFmpegNormalizeError("file " + input_file + " does not exist")
  
          ext = os.path.splitext(output_file)[1][1:]
          if (self.audio_codec is None or 'pcm' in self.audio_codec) and ext in PCM_INCOMPATIBLE_EXTS:
              raise FFmpegNormalizeError(
                  "Output extension {} does not support PCM audio. Please choose a suitable audio codec with the -c:a option.".format(ext)
              )
  
          mf = MediaFile(self, input_file, output_file)
          self.media_files.append(mf)
  
          self.file_count += 1
docs: Add a media file to normalize
  
          Arguments:
              input_file {str} -- Path to input file
              output_file {str} -- Path to output file