Drop the length of a particular audio file and junk into your Jekyll page.

jekyll_media_length.rb

# jekyll_media_length / by @holman
#
#   Drop the length of a particular audio file and junk into your Jekyll page.
#   (See https://twitter.com/Una/status/655856628198014976 for more context).
#
# INSTALL:
#
#   brew install taglib
#   gem install taglib-ruby
#
#   Toss this file into your _plugins directory.
#
# USAGE:
#
#   In your HTML page webzone device, do a liquid tag with the path to the audio
#   file, like:
#
#     {% media_length media/song.mp3 %}
#     # => 4:12
#
# YAY NEATO
#
#   Have a cupcake, you've earned it.
#

require 'taglib'

module Jekyll
  class MediaLength < Liquid::Tag
    def initialize(tag_name, filename, tokens)
      super
      @filename = filename.strip
    end

    def render(context)
      length = nil

      TagLib::FileRef.open(@filename) do |file|
        properties = file.audio_properties if file
        length = properties.length         if properties
      end

      if length
        minutes = length / 60
        seconds = length % 60

        "#{minutes}:#{"%.2d" % seconds}"
      end
    end
  end
end

Liquid::Template.register_tag('media_length', Jekyll::MediaLength)