2
3 import argparse
4 import logging
5 import shlex
6 import subprocess
7
9 Normalize audio input.
10
11 The command uses ffprobe to analyze an input file with the ebur128
12 filter, and finally run ffmpeg to normalize the input depending on the
13 computed adjustment.
14
15 ffmpeg encoding arguments can be passed through the extra arguments
16 after options, for example as in:
17 normalize.py --input input.mp3 --output output.mp3 -- -loglevel debug -y
18 '''
19
20 logging.basicConfig(format=
'normalize|%(levelname)s> %(message)s', level=logging.INFO)
21 log = logging.getLogger()
22
23
25 argparse.ArgumentDefaultsHelpFormatter, argparse.RawDescriptionHelpFormatter
27 pass
28
29
31 parser = argparse.ArgumentParser(description=HELP, formatter_class=Formatter)
32 parser.add_argument('--input', '-i', required=True, help='specify input file')
33 parser.add_argument('--output', '-o', required=True, help='specify output file')
34 parser.add_argument('--dry-run', '-n', help='simulate commands', action='store_true')
35 parser.add_argument('encode_arguments', nargs='*', help='specify encode options used for the actual encoding')
36
37 args = parser.parse_args()
38
39 analysis_cmd = [
40 'ffprobe', '-v', 'error', '-of', 'compact=p=0:nk=1',
41 '-show_entries', 'frame_tags=lavfi.r128.I', '-f', 'lavfi',
42 f"amovie='{args.input}',ebur128=metadata=1"
43 ]
44
45 def _run_command(cmd, dry_run=False):
46 log.info(f"Running command:\n$ {shlex.join(cmd)}")
47 if not dry_run:
48 result = subprocess.run(cmd, check=True, stdout=subprocess.PIPE)
49 return result
50
51 result = _run_command(analysis_cmd)
52
53 loudness = ref = -23
54 for line in result.stdout.splitlines():
55 sline = line.rstrip()
56 if sline:
57 loudness = sline
58
59 adjust = ref -
float(loudness)
60 if abs(adjust) < 0.0001:
61 logging.info(f"No normalization needed for '{args.input}'")
62 return
63
64 logging.info(f"Adjusting '{args.input}' by {adjust:.2f}dB...")
65 normalize_cmd = [
66 'ffmpeg', '-i', args.input, '-af', f'volume={adjust:.2f}dB'
67 ] + args.encode_arguments + [args.output]
68
69 _run_command(normalize_cmd, args.dry_run)
70
71
72 if __name__ == '__main__':