ffmpeg cut of from start and back - ruby convert script

README.md

Cut of from start/back of file

Useful for postprocessing various youtube videos with jingles/ad "follow us" stuff at the end.

ffmpeg has an easy way to cut off from beginning, but not to say "cut of 20s from the end". So one has to use to do arithmetics with duration. Here, using ruby script.

USAGE

ruby convert.rb 6 22 file_to_video.mp4 out/

will cut off 6s from beginning and 22s from the end of the file and will write the result to out/ folder.

convert.rb

#!/usr/bin/env ruby

if ARGV.length != 4
  $stderr.puts "USAGE: #{__FILE__} CutOfFromStart CutOfFromEnd InFile OutDir"
  $stderr.puts " example : #{__FILE__} file.mp4 0 7 out/  will cut off 7 seconds from the end"
  exit 1
end

require 'shellwords'

def e(arg)
  Shellwords.escape(arg)
end

cut_of_front, cut_of_back, in_file, out_file = ARGV

length = `ffprobe -v 0 -show_entries format=duration -of compact=p=0:nk=1 #{e in_file}`.to_f

cmd = "ffmpeg -i #{e in_file} -ss #{cut_of_front.to_i} -to #{length.floor - cut_of_back.to_i} #{e File.join(out_file, in_file)}"
puts cmd
exec cmd