Class: Plaything

Inherits:
Object
  • Object
show all
Defined in:
lib/plaything.rb,
lib/plaything/openal.rb,
lib/plaything/version.rb,
lib/plaything/objects/buffer.rb,
lib/plaything/objects/device.rb,
lib/plaything/objects/source.rb,
lib/plaything/objects/context.rb,
lib/plaything/support/paramable.rb,
lib/plaything/support/type_class.rb,
lib/plaything/support/managed_pointer.rb

Defined Under Namespace

Modules: OpenAL

Constant Summary collapse

Error = 
Class.new(StandardError)
VERSION = 
"1.0.0"

Instance Method Summary collapse

Constructor Details

#initialize(options = { sample_type: :int16, sample_rate: 44100, channels: 2 }) ⇒ Plaything

Open the default output device and prepare it for playback.

Options Hash (options):

  • sample_type (Symbol) — default: :int16
  • sample_rate (Integer) — default: 44100
  • channels (Integer) — default: 2

Raises:



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# File 'lib/plaything.rb', line 17

def initialize(options = { sample_type: :int16, sample_rate: 44100, channels: 2 })
  @device  = OpenAL.open_device(nil)
  raise Error, "Failed to open device" if @device.null?

  @context = OpenAL.create_context(@device, nil)
  OpenAL.make_context_current(@context)
  OpenAL.distance_model(:none)
  OpenAL.listenerf(:gain, 1.0)

  FFI::MemoryPointer.new(OpenAL::Source, 1) do |ptr|
    OpenAL.gen_sources(ptr.count, ptr)
    @source = OpenAL::Source.new(ptr.read_uint)
  end

  @sample_type = options.fetch(:sample_type)
  @sample_rate = Integer(options.fetch(:sample_rate))
  @channels    = Integer(options.fetch(:channels))

  @sample_format = { [ :int16, 2 ] => :stereo16, }.fetch([@sample_type, @channels]) do
    raise TypeError, "unknown sample format for type [#{@sample_type}, #{@channels}]"
  end

  FFI::MemoryPointer.new(OpenAL::Buffer, 3) do |ptr|
    OpenAL.gen_buffers(ptr.count, ptr)
    @buffers = OpenAL::Buffer.extract(ptr, ptr.count)
  end

  @free_buffers = @buffers.clone
  @queued_buffers = []
  @queued_frames = []

  # 44100 int16s = 22050 frames = 0.5s (1 frame * 2 channels = 2 int16 = 1 sample = 1/44100 s)
  @buffer_size  = @sample_rate * @channels * 1.0
  # how many samples there are in each buffer, irrespective of channels
  @buffer_length = @buffer_size / @channels
  # buffer_duration = buffer_length / sample_rate

  @total_buffers_processed = 0
end

Instance Method Details

#<<(frames) ⇒ Object

Queue audio frames for playback.



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# File 'lib/plaything.rb', line 99

def <<(frames)
  if buffers_processed > 0
    FFI::MemoryPointer.new(OpenAL::Buffer, buffers_processed) do |ptr|
      OpenAL.source_unqueue_buffers(@source, ptr.count, ptr)
      @total_buffers_processed += ptr.count
      @free_buffers.concat OpenAL::Buffer.extract(ptr, ptr.count)
      @queued_buffers.delete_if { |buffer| @free_buffers.include?(buffer) }
    end
  end

  wanted_size = (@buffer_size - @queued_frames.length).div(@channels) * @channels
  consumed_frames = frames.take(wanted_size)
  @queued_frames.concat(consumed_frames)

  if @queued_frames.length >= @buffer_size and @free_buffers.any?
    current_buffer = @free_buffers.shift

    FFI::MemoryPointer.new(@sample_type, @queued_frames.length) do |frames|
      frames.public_send(:"write_array_of_#{@sample_type}", @queued_frames)
      # stereo16 = 2 int16s (1 frame) = 1 sample
      OpenAL.buffer_data(current_buffer, @sample_format, frames, frames.size, @sample_rate)
      @queued_frames.clear
    end

    FFI::MemoryPointer.new(OpenAL::Buffer, 1) do |buffers|
      buffers.write_uint(current_buffer.to_native)
      OpenAL.source_queue_buffers(@source, buffers.count, buffers)
    end

    @queued_buffers.push(current_buffer)
  end

  consumed_frames.length
end

#drops ⇒ Integer 



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# File 'lib/plaything.rb', line 92

def drops
  0
end

#pause ⇒ Object

Pause playback of queued audio. Playback will resume from current position when #play is called.



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# File 'lib/plaything.rb', line 65

def pause
  OpenAL.source_pause(@source)
end

#play ⇒ Object

Note:

You must continue to supply audio, or playback will cease.

Start playback of queued audio.



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# File 'lib/plaything.rb', line 60

def play
  OpenAL.source_play(@source)
end

#position ⇒ Rational 



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# File 'lib/plaything.rb', line 82

def position
  Rational(@total_buffers_processed * @buffer_length + sample_offset, @sample_rate)
end

#queue_size ⇒ Integer 



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# File 'lib/plaything.rb', line 87

def queue_size
  @source.get(:buffers_queued, Integer) * @buffer_length - sample_offset
end

#stop ⇒ Object

Note:

All audio queues are completely cleared, and #position is reset.

Stop playback and clear any queued audio.



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# File 'lib/plaything.rb', line 72

def stop
  OpenAL.source_stop(@source)
  @source.detach_buffers
  @free_buffers.concat(@queued_buffers)
  @queued_buffers.clear
  @queued_frames.clear
  @total_buffers_processed = 0
end