constant-source-node.mdx

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import AudioNodePropsTable from "@site/src/components/AudioNodePropsTable" import { Optional, ReadOnly } from '@site/src/components/Badges';

ConstantSourceNode

The ConstantSourceNode is an AudioScheduledSourceNode which represents an audio source, that outputs a single constant value. The offset parameter controls this value. Although the node is called "constant" its offset value can be automated to change over time, which makes it powerful tool for controlling multiple other AudioParam values in an audio graph. Just like AudioScheduledSourceNode, it can be started only once.

Constructor

constructor(context: BaseAudioContext, options?: ConstantSourceOptions)

ConstantSourceOptions

Parameter	Type	Default
offset	number	1	Initial value for offset

Or by using BaseAudioContext factory method: BaseAudioContext.createConstantSource() that creates node with default values.

Example

import React, { useRef } from 'react';
import { Text } from 'react-native';
import {
  AudioContext,
  OscillatorNode,
  GainNode,
  ConstantSourceNode
} from 'react-native-audio-api';

function App() {
  const audioContextRef = useRef<AudioContext | null>(null);
  if (!audioContextRef.current) {
    audioContextRef.current = new AudioContext();
  }
  const audioContext = audioContextRef.current;

  const oscillator1 = audioContext.createOscillator();
  const oscillator2 = audioContext.createOscillator();
  const gainNode1 = audioContext.createGain();
  const gainNode2 = audioContext.createGain();
  const constantSource = audioContext.createConstantSource();

  oscillator1.frequency.value = 440;
  oscillator2.frequency.value = 392;
  constantSource.offset.value = 0.5;

  oscillator1.connect(gainNode1);
  gainNode1.connect(audioContext.destination);

  oscillator2.connect(gainNode2);
  gainNode2.connect(audioContext.destination);

  // We connect the constant source to the gain nodes gain AudioParams
  // to control both of them at the same time
  constantSource.connect(gainNode1.gain);
  constantSource.connect(gainNode2.gain);

  oscillator1.start(audioContext.currentTime);
  oscillator2.start(audioContext.currentTime);
  constantSource.start(audioContext.currentTime);
}

Properties

It inherits all properties from AudioScheduledSourceNode.

Name	Type	Default value	Description
offset	AudioParam	1.0	a-rate AudioParam representing the value which the node constantly outputs.

Methods

It inherits all methods from AudioScheduledSourceNode.