ffmpeg/tools/loudnorm.rb

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#!/usr/bin/env ruby
require 'open3'
require 'json'
ffmpeg_bin = 'ffmpeg'
target_il = -24.0
target_lra = +11.0
target_tp = -2.0
samplerate = '48k'
if ARGF.argv.count != 2
puts "Usage: #{$PROGRAM_NAME} input.wav output.wav"
exit 1
end
ff_cmd = Array.new([
ffmpeg_bin,
'-hide_banner',
'-i', ARGF.argv[0],
'-af', "loudnorm='I=#{target_il}:LRA=#{target_lra}:tp=#{target_tp}:print_format=json'",
'-f', 'null',
'-']);
_stdin, _stdout, stderr, wait_thr = Open3.popen3(*ff_cmd)
if wait_thr.value.success?
stats = JSON.parse(stderr.read.lines[-12, 12].join)
loudnorm_string = 'loudnorm='
loudnorm_string += 'print_format=summary:'
loudnorm_string += 'linear=true:'
loudnorm_string += "I=#{target_il}:"
loudnorm_string += "LRA=#{target_lra}:"
loudnorm_string += "tp=#{target_tp}:"
loudnorm_string += "measured_I=#{stats['input_i']}:"
loudnorm_string += "measured_LRA=#{stats['input_lra']}:"
loudnorm_string += "measured_tp=#{stats['input_tp']}:"
loudnorm_string += "measured_thresh=#{stats['input_thresh']}:"
loudnorm_string += "offset=#{stats['target_offset']}"
else
puts stderr.read
exit 1
end
ff_cmd = Array.new([
ffmpeg_bin,
'-y', '-hide_banner',
'-i', ARGF.argv[0],
'-af', loudnorm_string,
'-ar', samplerate,
ARGF.argv[1].to_s]);
_stdin, _stdout, stderr, wait_thr = Open3.popen3(*ff_cmd)
if wait_thr.value.success?
puts stderr.read.lines[-12, 12].join
exit 0
else
puts stderr.read
exit 1
end