Simple macOS script for taking screenshots every X seconds on multiple displays

record-screen-timelapse.rb

#! /usr/bin/env ruby

require 'time'

def usage
  puts "USAGE: ./record-timelapse every 10 displays 1,2"
end

if ARGV[0] != "every" || ARGV[2] != "displays"
  usage
  exit
end

sleep_duration = ARGV[1].to_i
displays = ARGV[3].split(",").map(&:to_i)

puts "Taking screenshots of displays: #{display} every #{sleep_duration} seconds"
puts "Starting in 3 seconds..."
sleep(3)

displays.each do |display|
  `mkdir display#{display}`
end

loop do
  now = Time.now.strftime('%Y-%m-%dT%H-%M-%S')

  displays.each do |display|
    filename = "display#{display}/screenshot-at-#{now}.png"
    `screencapture -D#{display} -C -x #{filename}`
  end
  puts "captured at #{now}"

  sleep(sleep_duration)
end

# https://trac.ffmpeg.org/wiki/Slideshow
#
# -framerate X : how many images to show per second
# -r Y : output framerate (should probably be multiple of X, and either 24, 30 or 60)
#
# ffmpeg -framerate 15 -pattern_type glob -i "./display1/*.png" -c:v libx264 -r 30 -pix_fmt yuv420p display1.mp4