Ruby En Rails 2007 Conference

Posted by andy

On June 7th the Ruby En Rails 2007 Conference will be held here in Amsterdam. I'm really looking forward to meeting up with the dutch Rails crowd. I'll be giving a lighting talk on Mongrel clustering and will share my experience with this in use on a busy site. Also looking forward to some of the talks, especially the opening keynote. Hope to see you there!!

Update: I just read there are no more seats left, so hope you got in!

Using MPlayer identify with Ruby

Posted by andy

For a project I need to fetch some metadata from WAV recordings. Mplayer can extract this information nicely with the -identify command. I’m using Ruby Sessions for executing the external mplayer command, although a simple IO.POpen() might do fine too. The code wrapper class looks like this:

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require 'rubygems'
require_gem 'session'

class MediafileInfo
        MPLAYER_BINARY = "mplayer"
        MPLAYER_IDENTIFY = "-identify -vo null -ao null -frames 0"

        def initialize(filename)
                stdout, stderr = '', ''
                shell = Session::Shell.new
                shell.execute "#{MPLAYER_BINARY} #{MPLAYER_IDENTIFY} #{filename}", :stdout => stdout, :stderr => stderr

                vars = (stdout.split(/\n/).collect! { |o| o if o =~ /^ID_/ } ).compact!

                vars.each { |v|
                        a, b = v.split("=")
                        eval "@#{a.to_s.downcase} = \"#{b}\""
                }
        end

        # Intercept calls
        def method_missing(method_name, *args)
                value = eval "@id_#{method_name.to_s.downcase}"
        end
end

All ID_* lines that mplayer spits out will now be method calls (and instance variables) of your MediafileInfo object. The method_missing call is there to do proper value defaulting if the variable doesn’t exist, but I’m not using it as such right now. To get the playing time of every type of mediafile that mplayer understands you simply do someting like: 
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info = MediafileInfo.new("voicemail.wav")

puts "Voicemail playtime: #{info.length.to_i} seconds"
Ruby 0wnz! :)