#!/usr/bin/env python3 import argparseimport loggingimport shleximport subprocess HELP = '''Normalize audio input. The command uses ffprobe to analyze an input file with the ebur128filter, and finally run ffmpeg to normalize the input depending on thecomputed adjustment. ffmpeg encoding arguments can be passed through the extra argumentsafter options, for example as in:normalize.py --input input.mp3 --output output.mp3 -- -loglevel debug -y''' logging.basicConfig(format='normalize|%(levelname)s> %(message)s', level=logging.INFO)log = logging.getLogger()  class Formatter(    argparse.ArgumentDefaultsHelpFormatter, argparse.RawDescriptionHelpFormatter):    pass  def normalize():    parser = argparse.ArgumentParser(description=HELP, formatter_class=Formatter)    parser.add_argument('--input', '-i', required=True, help='specify input file')    parser.add_argument('--output', '-o', required=True, help='specify output file')    parser.add_argument('--dry-run', '-n', help='simulate commands', action='store_true')    parser.add_argument('encode_arguments', nargs='*', help='specify encode options used for the actual encoding')     args = parser.parse_args()     analysis_cmd = [        'ffprobe', '-v', 'error', '-of', 'compact=p=0:nk=1',        '-show_entries', 'frame_tags=lavfi.r128.I', '-f', 'lavfi',        f"amovie='{args.input}',ebur128=metadata=1"    ]     def _run_command(cmd, dry_run=False):        log.info(f"Running command:\n$ {shlex.join(cmd)}")        if not dry_run:            result = subprocess.run(cmd, check=True, stdout=subprocess.PIPE)            return result     result = _run_command(analysis_cmd)     loudness = ref = -23    for line in result.stdout.splitlines():        sline = line.rstrip()        if sline:            loudness = sline     adjust = ref - float(loudness)    if abs(adjust) < 0.0001:        logging.info(f"No normalization needed for '{args.input}'")        return     logging.info(f"Adjusting '{args.input}' by {adjust:.2f}dB...")    normalize_cmd = [        'ffmpeg', '-i', args.input, '-af', f'volume={adjust:.2f}dB'    ] + args.encode_arguments + [args.output]     _run_command(normalize_cmd, args.dry_run)  if __name__ == '__main__':    normalize()