Recompression vidéo H264/H265

video_recompress.rb

#!/usr/bin/env ruby
# frozen_string_literal: true

require 'optparse'
require 'ostruct'

DEFAULT_X264_PARAMS = {
  'b-adapt'      => 2,
  'ref'          => 16,
  'direct'       => 'auto',
  'trellis'      => 2,
  'analyse'      => 'all',
  'merange'      => 24,
  'me'           => 'umh',
  'rc-lookahead' => 48,
  'bframes'      => 6
}.freeze

def encoders
  %w(x264 x265)
end

def video_sizes
  %w(480p 576p 720p 1080p native)
end

def audio_formats
  %w(mono stereo)
end

# All video file extension parsed by default
def accepted_file_extensions
  %w(mp4 mts m2ts mov).flat_map { |e| [e, e.upcase] }
end

# By default use mono 64 kbps AAC audio, as we never have the need for stereo
# using smartphone / DSLR recordings
def audio_flags
  if flags.audio == 'stereo'
    '--ab 128'
  else
    '--ab 64 --mixdown mono'
  end
end

def encoder_flags
  flags.encoder = 'x264' unless flags.encoder == 'x265'

  "-e #{flags.encoder}"
end

def size_flags
  height = flags.resolution.to_i
  width = (height * 16).div(9)
  "--width #{width} --height #{height}" if height > 0
end

def x264_flags
  params = DEFAULT_X264_PARAMS.dup

  if flags.resolution.to_i > 720
    params['rc-lookahead'] = 64
    params['bframes'] = 8
  end

  values = params.map { |k, v| "#{k}=#{v}" }.join(':')
  "-x '#{values}'"
end

# x264 presets guide : https://forum.handbrake.fr/viewtopic.php?f=6&t=19426
flags = OpenStruct.new
flags.optim = '--optimize --use-opencl --use-hwd --format mp4'

OptionParser.new do |opts|
  opts.banner = 'Usage: video_recompress files [options]'

  opts.on('-r', '--resolution [native]', video_sizes, 'Video height') do |o|
    flags.resolution = o
  end

  opts.on('-a', '--audio-format [mono]', audio_formats, 'Audio format') do |o|
    flags.audio = o
  end

  opts.on('-e', '--encoder [x264]', encoders, 'Force H265 encoding') do |o|
    flags.encoder = o
  end

  opts.on('-o', '--output DIRECTORY', String, 'Destination directory') do |o|
    flags.output = o
  end

  opts.on('-h', '--help', 'Displays help') do
    puts opts
    exit
  end
end.parse!

# require 'pp'
# pp flags
#
mask = File.join(ARGV.last, "*.{#{accepted_file_extensions.join(',')}}")
puts "Globbing #{mask} ..."
Dir.glob(mask) do |entry|
  puts "Processing : #{entry}\n"
  next unless File.file? entry

  source_dir     = File.dirname(entry)
  source_prefix  = File.basename(entry, '.*')
  # archive_dir  = File.join(source_dir, '..', "out-#{flags.height}")
  dest_dir       = File.join(source_dir, '..', 'out-originals')
  flags.output ||= File.join(dest_dir, "#{source_prefix} - .mp4")
  # Dir.mkdir(flags.output)

  # Compress video file
  # -v0 flag disabled most of the verbosity
  command = []
  command << '/Applications/HandBrakeCLI -v0'
  command << "-i '#{entry}'"
  command << "-o '#{flags.output}'"
  command << flags.optim
  command << audio_flags
  command << size_flags
  command << "--quality #{flags.quality || 23}"
  command << encoder_flags
  command << x264_flags
  command.compact!
  command = command.join(' ')
  puts "Running    : #{command}\n"
  # system command

  # # We have to open the source file to read its mtime and attribute it to
  # # the encoded file
  # File.utime Time.now, File.new(entry).mtime, flags.destination
  #
  # # Move original file to archive directory
  # Dir.mkdir(archive_dir)
  # File.mv(source_file, archive_dir)
end