Script to break down YouTube playlist audio into separate files per-track, based on YouTube description/comment track lists. Depends on commandline ffmpeg

youtube-playlist-split.rb

#!/usr/bin/env ruby

require 'shellwords'
require 'open3'
require 'pry-rails'

if ARGV.length < 2
  case ARGV[0] 
  when nil, "--help"
    puts "Usage: youtube-playlist-split.rb AUDIO_FILE PLAYLIST_FILE
    
Will break apart a video or audio file in its current directory, according to track start times specified in PLAYLIST_FILE (in typical YouTube format)

Options:
  --help               Print this help
  --example-playlist   Show example playlist
    "
  when '--example-playlist'
    puts "example playlist:

1. Artist - Song 12:24
2. My Artist - My Song 42:20
3. Other Artist - Your Song 01:12:20"
  end
  exit
end

source = File.expand_path(ARGV[0])
pl = File.expand_path(ARGV[1])

ext = source.split('.').last
dir = source.split('/')[0..-2].join('/') + "/"

duration_str = Open3.capture3("ffmpeg -i #{Shellwords.escape(source)}")[1].match(/Duration: [\d:]*/).to_s.gsub("Duration: ","")

manifest = {}

trackstrs = File.read(pl).split("\n")

trackstrs.each do |x|
  filename = x.gsub(/[\d:]*$/, '').strip
  manifest[filename.to_sym] = {
    start_time: x.match(/[\d:]+:[\d:]+/).to_s
  }
end

def parsetime(str)
  str.split(':').map(&:to_i).inject(0) { |a, b| a * 60 + b }
end

mks = manifest.keys
mks.each_with_index do |k,i|
  next_item = manifest[mks[i+1]]
  if next_item
    next_str = next_item[:start_time]
  else
    next_str = duration_str
  end
  manifest[k][:end_time] = next_str
  manifest[k][:len] = parsetime(manifest[k][:end_time]) - parsetime(manifest[k][:start_time])
  filename = k.to_s.gsub(manifest[k][:start_time], '').strip
  # binding.pry
  if !filename.to_s.match(/^[\d]+/)
    filename = "#{i.to_s.rjust(2, "0")} #{filename}"
  end 
  filename = "#{Shellwords.escape(dir)}#{Shellwords.escape(filename)}.#{ext}"
  manifest[k][:filename] = filename
end

puts "Parsed track list:"
manifest.each do |k,v|
  puts "Filename: #{v[:filename]}"
  puts "Start time: #{v[:start_time]}     End time: #{v[:end_time]}     Length: #{v[:len]}"
end
puts "Proceed? Y/n"
answer = $stdin.gets.chomp
exit if answer.downcase == "n"

manifest.each.with_index do |x,i|
  # k = x[0]
  v = x[1]

  cmd = "ffmpeg -i #{Shellwords.escape(source)} -ss #{Shellwords.escape(v[:start_time])} -t #{Shellwords.escape(v[:len])} -c:a copy #{v[:filename]}"
  # binding.pry
  puts "Executing: " + cmd
  puts `#{cmd}`
  puts
  puts "-----------------------------------------------------"
  puts
end