mov-to-gif - .movからanimation GIFを作る

mov-to-gif.rb

#!/usr/bin/env ruby

require 'tmpdir'

if ARGV.length != 3
  puts "mov-to-gif: Create animation GIF"
  puts "Usage: mov-to-gif 1 input.mov output.gif     -- normal (x1)"
  puts "Usage: mov-to-gif 2 input.mov output.gif     -- faster (x2)"
  puts "Usage: mov-to-gif 0.5 input.mov output.gif   -- slower (x0.5)"
  abort
end

rate = ARGV[0].to_f
movname = ARGV[1]
gifname = ARGV[2]

Dir.mktmpdir do |tmpdir|
  palette = "#{tmpdir}/palette.png"
  cmd = "ffmpeg -i #{movname} -vf fps=20,palettegen=stats_mode=diff -y #{palette}"
  puts cmd
  system(cmd)
  cmd = "ffmpeg -i #{movname} -i #{palette} -lavfi setpts=PTS/#{rate},fps=20,paletteuse -y #{gifname}"
  puts cmd
  system(cmd)
end

# cf.
# http://genjiapp.com/blog/2015/05/05/generating-much-better-animated-gif-from-movie-file.html
# http://fftest33.blog.fc2.com/blog-entry-36.html