Beginnings of a rudimentary CLI telemetry utility for Assetto Corsa written in Ruby.

ac-telemetry.rb

#!/usr/bin/env ruby

$: << './lib'

require 'socket'
require 'bindata'
require 'json'

class UTF8String < BinData::String
  def snapshot
    super.force_encoding('UTF-8')
  end
end

class BinData::String
  def snapshot
    super.force_encoding('UTF-16LE')
  end
end

class Handshaker < BinData::Record
  int32le :identifier
  int32le :version
  int32le :operation_id
end

class HandshakerResponse < BinData::Record
  string :car_name, read_length: 100
  string :driver_name, read_length: 100
  int32le :identifier
  int32le :version
  string :track_name, read_length: 100
  string :track_config, read_length: 100
end

class RTCarInfo < BinData::Record
  string :identifier, read_length: 4, trim_padding: true
  int32le :rt_size
  float_le :speed_kmh
  float_le :speed_mph
  float_le :speed_ms
  int8 :is_abs_enabled
  int8 :is_abs_in_action
  int8 :is_tc_in_action
  int8 :is_tc_enabled
  int8 :is_in_pit
  int8 :is_engine_limiter_on
  float_le :acc_g_vertical
  float_le :acc_g_horizontal
  float_le :acc_g_frontal
  int32le :lap_time
  int32le :last_lap
  int32le :best_lap
  int32le :lap_count
  float_le :gas
  float_le :brake
  float_le :clutch
  float_le :engine_rpm
  float_le :steer
  int32le :gear
  float_le :cg_height
  float_le :wheel_angular_speed
  float_le :slip_angle
  float_le :slip_angle_contact_patch
  float_le :slip_ratio
  float_le :tyre_slip
  float_le :nd_slip
  float_le :load
  float_le :dy
  float_le :mz
  float_le :tyre_dirty_level
  float_le :camber_rad
  float_le :tyre_radius
  float_le :tyre_loaded_radius
  float_le :suspension_height
  float_le :car_position_normalized
  float_le :car_slope
  float_le :car_coordinates
end

class RTLap < BinData::Record
  int32le :car_identifier_number
  int32le :lap
  string :driver_name, read_length: 100
  string :car_name, read_length: 100
  int32le :time
end

class Parser
  def detect(record)
    case record[:bytesize]
    when 408
      handle_handshake_response(record)
    when 328
      handle_rtcarinfo(record)
    else
      nil
    end
  end

  def handle_handshake_response(record)
    HandshakerResponse.read(record[:snap])
  end

  def handle_rtcarinfo(record)
    RTCarInfo.read(record[:snap])
  end
end

class ACTelemetry
  AC_PORT = 9996
  AC_HANDSHAKE = Handshaker.new(identifier: 1, version: 1, operation_id: 0).to_binary_s
  AC_UPDATE = Handshaker.new(identifier: 1, version: 1, operation_id: 1).to_binary_s
  AC_DISMISS = Handshaker.new(identifier: 1, version: 1, operation_id: 3).to_binary_s

  CLIENT_PORT = 9999
  CLIENT_IP_ADDR = '0.0.0.0'

  def initialize(args)
    @ac_ip_addr = args.pop
    @udp = UDPSocket.new
    @udp.bind(CLIENT_IP_ADDR, CLIENT_PORT)
    @parser = Parser.new
  end

  def run!
    listen
    loop do
      timestamp = -> { Time.now.to_s }

      $stderr.puts "Command? [(h)andshake,(u)pdate,(d)ismiss,(t)test,(q)uit]"
      cmd = gets.chomp

      case cmd
      when "h"
        request :handshake
      when "u"
        request :update
      when "d"
        request :dismiss
      when "t"
        msg = "Test: #{timestamp.call}"
        $stderr.puts "Sending test message to #{@ac_ip_addr}:#{AC_PORT}"
        request msg
      when "q"
        $stderr.puts "Exiting..."
        exit 0
      end
    end
  end

  def request(type)
    case type
    when :handshake
      $stderr.puts "Sending handshake..."
      send(AC_HANDSHAKE)
    when :update
      $stderr.puts "Sending update..."
      send(AC_UPDATE)
    when :dismiss
      $stderr.puts "Sending dismiss..."
      send(AC_DISMISS)
    else
      send(type)
    end
  end

  def listen
    Thread.new do
      reader do |record|
        $stdout.print "#{record.inspect}\n" if @debug
        $stdout.print "#{@parser.detect(record).inspect}\n"
        $stdout.flush
      end
    end
  end

  def reader
    loop do
      data, addrinfo = @udp.recvfrom(4096)
      host, port = addrinfo[3], addrinfo[1]
      record = {
        host: host,
        port: port,
        bytesize: data.bytesize,
        snap: data
      }
      yield record
    end
  end

  def send(msg)
    @udp.send(msg,0,@ac_ip_addr,AC_PORT)
  end
end

begin
  if $0 == __FILE__
    ACTelemetry.new(ARGV).run!
  end
rescue Interrupt
  # Ctrl^C
  exit 130
rescue Errno::EPIPE
  # STDOUT was closed
  exit 74 # EX_IOERR
end