flatten3davi.rb

require 'fileutils'
require 'tmpdir'
require 'cocaine'
require 'aviglitch'

infile = ARGV.shift
skip = (ARGV.shift || 1).to_i
outfile = './out.avi'
info = Cocaine::CommandLine.new('ffmpeg', '-i :in 2>&1', :expected_outcodes => [0, 1]).run(:in => infile)
tbc = info.match /(¥d+) tbc/
if tbc.nil?
  puts "Usage: ruby %s <infile>" % $0
  exit 1
end
fps = (2 * tbc[1].to_i).to_s

audio, video1, video2 = ()
audiom = info.scan /Stream #([¥d:]+): Audio:/
unless audiom.empty?
  audio = audiom[0][0]
end
videom = info.scan /Stream #([¥d:]+): Video:/
unless videom.empty?
  video1 = videom[0][0]
  video2 = videom[1][0]
end

Dir.mktmpdir do |dir|
  audioout = "%s/audio.wav" % dir
  videoout = "%s/video.avi" % dir
  video1out = "%s/video1.avi" % dir
  video2out = "%s/video2.avi" % dir
  cmd = Cocaine::CommandLine.new 'ffmpeg', '-i :in -map :map -r :fps -codec copy -y :out'
  cmd.run :in => infile, :map => audio, :fps => fps, :out => audioout
  cmd.run :in => infile, :map => video1, :fps => fps, :out => video1out
  cmd.run :in => infile, :map => video2, :fps => fps, :out => video2out
  va = AviGlitch.open video1out
  vb = AviGlitch.open video2out
  vbase = AviGlitch.open video2out  # AviGlitch::Frames must has #clone method
  vbase.glitch_with_index do |d, i|
    pos = (i / skip).to_i
    p = pos * skip
    p += 1 unless p % 2 == 0
    t = pos % 2 == 0 ? va : vb
    t.frames[p].data
  end
  vbase.output videoout
  cmd = Cocaine::CommandLine.new 'ffmpeg', '-i :video -i :audio -codec copy -y :out'
  cmd.run :audio => audioout, :video => videoout, :out => outfile
end