#!/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 math
import os.path
import subprocess

parser = argparse.ArgumentParser(description='Normalise audio files using FFmpeg loudnorm')
parser.add_argument('filename', nargs='+', help='Input files')
parser.add_argument('--loudness', '-i', default=-24, type=float, help='Target loudness')
parser.add_argument('--outdir', '-o', default='.', help='Output directory')
parser.add_argument('--outfmt', '-t', default='wav', help='Output file format suffix')
parser.add_argument('--levels', '-l', default='levels.json', help='levels.json output file')
parser.add_argument('--args', '-a', default='', help='Additional arguments to pass to FFmpeg')
args = parser.parse_args()

with open(args.levels, 'r') as f:
	levels = json.load(f)

avg_i = 0
for _, level in levels.items():
	avg_i += 10**(float(level['input_i'])*10)
avg_i /= len(levels)
avg_i = math.log10(avg_i)/10

for filename in args.filename:
	print(filename)
	
	target_loudness = args.loudness + (float(levels[filename]['input_i']) - avg_i)
	
	cmd = ['ffmpeg', '-i', filename, '-filter:a']
	cmd.append('loudnorm=i={}:measured_i={}:measured_lra={}:measured_tp={}:measured_thresh={}:linear=true'.format(target_loudness, levels[filename]['input_i'], levels[filename]['input_lra'], levels[filename]['input_tp'], levels[filename]['input_thresh']))
	cmd.extend(args.args.split())
	cmd.append(os.path.join(args.outdir, os.path.splitext(filename)[0] + '.' + args.outfmt))
	
	proc = subprocess.run(cmd)
	
	if proc.returncode != 0:
		print('FFmpeg error')
		sys.exit(1)