A ruby command-line justin.tv/twitch.tv player. Requires rtmpdump 2.4, uses mplayer by default.

justin.rb

#!/usr/bin/env ruby
require 'rubygems'
require 'json'
require 'faraday'

# Script options
channel=ARGV[0]
stream=ENV['STREAM'] || "live"
player=ENV['PLAYER'] || "mplayer -quiet"

# Get an API request, parse as JSON, return an object
def get(url)
  response = Faraday.get url
  object = JSON.parse(response.body)
end

# Follow HTTP 302 once, give out proper location
def locate(url)
  response = Faraday.head url
  response.headers['location'] || url
end

# Usher gives us most rtmpdump parameters we need
response = get "http://usher.justin.tv/find/#{channel}.json?type=#{stream}"
info = response[0] # always return a list, only need the first element

# Justin generates a unique swf address with a built-in token
swf = locate 'http://www.justin.tv/widgets/live_site_player.swf'

# rtmp address components
connect = info['connect']
play = info['play']
rtmp = "#{connect}/#{play}"

# token has embedded json, escape quotes
token = info['token'].gsub('"', '\\"')

cmdline = "rtmpdump -r\"#{rtmp}\" -j\"#{token}\" -W\"#{swf}\" -m5 -o - | #{player} -"
puts cmdline
system(cmdline)