datamoshing.rb

#!/usr/bin/env ruby
# remove key frame information from AVI (codec: Cinepak)
# example result http://www.vimeo.com/3334387

# a name of AVI file
filename = ARGV.shift

f = open(filename)
data = f.read
f.close

main, index = data.split('idx1')
frames = main.split('00dc')
header = frames.shift

indexes = index.split('00dc')
indexes.shift

frames.each_with_index do |frame, i|
  if indexes[i][0] == 18
    frames[i] = "\x00" * frame.size
  end
end

print [([header] + frames).join('00dc'), index].join('idx1')