Add an example for how to use AudioStreamGenerator

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VolTer 2023-04-23 17:12:42 +02:00
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<?xml version="1.0" encoding="UTF-8" ?>
<class name="AudioStreamGenerator" inherits="AudioStream" version="4.1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
<brief_description>
Audio stream that generates sounds procedurally.
An audio stream with utilities for procedural sound generation.
</brief_description>
<description>
This audio stream does not play back sounds, but expects a script to generate audio data for it instead. See also [AudioStreamGeneratorPlayback].
[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 [AudioStreamGeneratorPlayback].
Here's a sample on how to use it to generate a sine wave:
[codeblock]
var playback # Will hold the AudioStreamGeneratorPlayback.
@onready var sample_hz = $AudioStreamPlayer.stream.mix_rate
var pulse_hz = 440.0 # The frequency of the sound wave.
func _ready():
$AudioStreamPlayer.play()
playback = $AudioStreamPlayer.get_stream_playback()
fill_buffer()
func fill_buffer():
var phase = 0.0
var increment = pulse_hz / sample_hz
var frames_available = playback.get_frames_available()
for i in range(frames_available):
playback.push_frame(Vector2.ONE * sin(phase * TAU))
phase = fmod(phase + increment, 1.0)
[/codeblock]
In the example above, the "AudioStreamPlayer" node must use an [AudioStreamGenerator] as its stream. The [code]fill_buffer[/code] function provides audio data for approximating a sine wave.
See also [AudioEffectSpectrumAnalyzer] for performing real-time audio spectrum analysis.
[b]Note:[/b] 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 [member mix_rate] such as 11,025 Hz or 22,050 Hz.
</description>
<tutorials>
<link title="Audio Generator Demo">https://godotengine.org/asset-library/asset/526</link>
<link title="Godot 3.2 will get new audio features">https://godotengine.org/article/godot-32-will-get-new-audio-features</link>
</tutorials>
<members>
<member name="buffer_length" type="float" setter="set_buffer_length" getter="get_buffer_length" default="0.5">