#!/usr/bin/env python3
#    ffmpeg-album-normalise: Normalise music album-by-album using FFmpeg loudnorm
#    Copyright © 2019  Lee Yingtong Li (RunasSudo)
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Affero General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU Affero General Public License for more details.
#
#    You should have received a copy of the GNU Affero General Public License
#    along with this program.  If not, see <https://www.gnu.org/licenses/>.

import argparse
import json
import os.path
import subprocess
import sys

parser = argparse.ArgumentParser(description='Scan audio files for loudness')
parser.add_argument('filename', nargs='+', help='Input files')
parser.add_argument('--levels', '-l', default='levels.json', help='levels.json output file')
args = parser.parse_args()

levels = {}
if os.path.exists(args.levels):
	with open(args.levels, 'r') as f:
		levels = json.load(f)

for filename in args.filename:
	print(filename)
	
	if filename in levels:
		continue
	
	proc = subprocess.run(['ffmpeg', '-i', filename, '-filter:a', 'loudnorm=print_format=json', '-f', 'null', '-'], capture_output=True, encoding='utf-8')
	
	if proc.returncode != 0:
		print('FFmpeg error')
		sys.exit(1)
	
	data_str = proc.stderr[proc.stderr.index('{', proc.stderr.index('Parsed_loudnorm_0')):]
	data = json.loads(data_str)
	
	levels[filename] = data
	
	with open(args.levels, 'w') as f:
		json.dump(levels, f)