ffmpeg screenshots

thumbnail.rb

#!/usr/bin/ruby

require "streamio-ffmpeg"

class Video
  def initialize(f="", outf="./", at=[20, 50, 80])
    @video=FFMPEG::Movie.new(f)
    @at=at.map { |x| (@video.duration*x/100).to_i}
    $stderr.puts "Video #{f} (#{@video.duration} secs) - Screenshots at #{@at.inspect}"
  @outf=outf
  end

  def run
    bname=File.basename(@video.path)
    @at.length.times do |i|
      cmd="ffmpeg -y -i #{@video.path} -ss #{@at[i]} -vframes 1 -vf fps=fps=1 -f image2 #{@outf}/x#{bname}-#{i}.jpg "
      system(cmd ) #+ ' 2>/dev/null')
    end
  end

end

Screenshots=[20, 50, 80]
outf="./out"
Dir.mkdir(outf) unless File.directory?(outf)
v=Video.new(ARGV[0], outf, Screenshots)
v.run

Lazy to edit... But helps to have -ss before -i - This tiny change makes ffmpeg seek directly to the offset and not have to decode video sequence till then... i.e.

cmd="ffmpeg -y -ss #{@at[i]} -i #{@video.path} -vframes 1 -f image2 #{@outf}/#{bname}-#{i}.jpg "

^^^ Huge f****** speedup.