Ticket #733: coreaudio.rb

# -*- encoding: utf-8 -*-

framework "CoreAudio"

module CoreAudio
  # constants shortcut
  SystemObject = KAudioObjectSystemObject
  PropertyScopeGlobal = KAudioObjectPropertyScopeGlobal
  PropertyElementMaster = KAudioObjectPropertyElementMaster

  # typdef
  class AudioObjectID < Pointer
    def initialize
      super("I")
    end
  end
  class AudioDeviceID < AudioObjectID
  end
  class AudioStreamID < AudioObjectID
  end

  module_function

  def get_property(type, selector, scope=PropertyScopeGlobal, element=PropertyElementMaster)
    addr = AudioObjectPropertyAddress.new(selector, scope, element)
    size_p = Pointer.new_with_type("I")
    size_p[0] = 4
    if type.is_a?(Pointer)
      data_p = type
    elsif type.class < Pointer
      data_p = type.new
    else
      data_p = Pointer.new(type)
    end
    osstatus = AudioObjectGetPropertyData(SystemObject, addr, 0, nil, size_p, data_p)
    unless osstatus == 0
      raise "AudioObjectGetPropertyData() fail '#{[osstatus].pack("N")}'"
    end
    data_p[0]
  end

  def get_default_output_device
    devid_p = AudioDeviceID.new("I")
    get_property(devid_p, KAudioHardwarePropertyDefaultOutputDevice)
  end

  def create_io_proc_id(devid, &blk)
    proc_id_p = Pointer.new("^?")
    osstatus = AudioDeviceCreateIOProcID(devid, blk, nil, proc_id_p)
    unless osstatus == 0
      raise "AudioDeviceCreateIOProcID() fail '#{[osstatus].pack("N")}'"
    end
    proc_id_p[0]
  end

  def destroy_io_proc_id(devid, procid)
    osstatus = AudioDeviceDestroyIOProcID(devid, procid)
    unless osstatus == 0
      raise "AudioDeviceDestroyIOProcID() fail '#{[osstatus].pack("N")}'"
    end
    nil
  end

  def device_start(devid, procid)
    osstatus = AudioDeviceStart(devid, procid)
    unless osstatus == 0
      raise "AudioDeciceStart() fail '#{[osstatus].pack("N")}'"
    end
  end

  def device_stop(devid, procid)
    osstatus = AudioDeviceStop(devid, procid)
    unless osstatus == 0
      raise "AudioDeciceStop() fail '#{[osstatus].pack("N")}'"
    end
  end
end