AudioStreamGenerator

Overview ¶

graphics.gd/classdb/AudioStreamGenerator is a type of audio stream that does not play back sounds on its own; instead, it expects a script to generate audio data for it. See also graphics.gd/classdb/AudioStreamGeneratorPlayback.

Here's a sample on how to use it to generate a sine wave:

package main

import (
	"graphics.gd/classdb/AudioStreamGenerator"
	"graphics.gd/classdb/AudioStreamGeneratorPlayback"
	"graphics.gd/classdb/AudioStreamPlayer"
	"graphics.gd/classdb/Node"
	"graphics.gd/variant/Angle"
	"graphics.gd/variant/Float"
	"graphics.gd/variant/Object"
	"graphics.gd/variant/Vector2"
)

type ExampleAudioStreamGenerator struct {
	Node.Extension[ExampleAudioStreamGenerator]

	AudioStreamPlayer AudioStreamPlayer.Instance

	playback AudioStreamGeneratorPlayback.Instance

	sample_hz, pulse_hz Float.X
	phase               Angle.Radians
}

func (eg *ExampleAudioStreamGenerator) Ready() {
	eg.sample_hz = Object.To[AudioStreamGenerator.Instance](eg.AudioStreamPlayer.Stream()).AsAudioStreamGenerator().MixRate()
	eg.AudioStreamPlayer.Play()
	eg.playback = Object.To[AudioStreamGeneratorPlayback.Instance](eg.AudioStreamPlayer.GetStreamPlayback())
	eg.FillBuffer()
}

func (eg *ExampleAudioStreamGenerator) FillBuffer() {
	increment := Angle.Radians(eg.pulse_hz / eg.sample_hz)
	frames_available := eg.playback.GetFramesAvailable()
	for range frames_available {
		eg.playback.PushFrame(Vector2.AddX(Vector2.One, Angle.Sin(eg.phase*Angle.Tau)))
		eg.phase = Float.Mod(eg.phase+increment, 1.0)
	}
}

In the example above, the "AudioStreamPlayer" node must use an graphics.gd/classdb/AudioStreamGenerator as its stream. The fill_buffer function provides audio data for approximating a sine wave.

See also graphics.gd/classdb/AudioEffectSpectrumAnalyzer for performing real-time audio spectrum analysis.

Note: Due to performance constraints, this class is best used from C# or from a compiled language via GDExtension. If you still want to use this class from GDScript, consider using a lower Instance.MixRate such as 11,025 Hz or 22,050 Hz.