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/**
* A simple audio pipe that allows you to push audio data to the audio output.
* Will allow you to sequentially play audio data.
*/
export class AudioPipe {
constructor() {
this.initialized = false;
this.nextAvailableTime = 0;
this.gain = 1;
}
/**
* Initializes the audio pipe by creating an AudioContext.
*/
initialize() {
this.audioContext = new AudioContext();
this.gainNode = this.audioContext.createGain();
this.gainNode.connect(this.audioContext.destination);
this.gainNode.gain.value = this.gain;
this.initialized = true;
}
/**
* @returns {number} The volume of the audio pipe [0,1].
*/
get volume() {
return this.gain;
}
/**
* Sets the volume of the audio pipe.
*
* @param {number} value - The volume of the audio pipe [0,1].
*/
set volume(value) {
if (this.initialized) {
// Change volume [0,1] to gain [-1,1]
this.gainNode.gain.value = 2 * value - 1;
}
this.gain = value;
}
/**
* Pushes audio data to the audio output.
*
* @param {Float32Array} data - The audio data to play.
* @param {number} [sampleRate=48000] - The sample rate of the audio data.
*/
push(data, sampleRate = 48000) {
if (!this.initialized) {
this.initialize();
}
const audioBuffer = new AudioBuffer({
length: data.length,
numberOfChannels: 1,
sampleRate: sampleRate
});
audioBuffer.copyToChannel(data, 0);
const audioBufferNode = new AudioBufferSourceNode(
this.audioContext,
{ buffer: audioBuffer }
);
audioBufferNode.connect(this.gainNode);
audioBufferNode.start(this.nextAvailableTime);
if (this.nextAvailableTime > this.audioContext.currentTime) {
// There is already at least one scheduled node, so we need to update the next available time
this.nextAvailableTime += audioBuffer.duration;
} else {
this.nextAvailableTime = this.audioContext.currentTime + audioBuffer.duration;
}
return audioBufferNode;
}
/**
* Pushes silence to the audio output.
*
* @param {number} duration - The duration of the silence in seconds.
* @param {number} [sampleRate=48000] - The sample rate of the silence.
*/
pushSilence(duration, sampleRate = 48000) {
if (!this.initialized) {
return; // Don't initialize for silence
}
const data = new Float32Array(Math.floor(duration * sampleRate));
this.push(data, sampleRate);
}
/**
* @returns {boolean} Whether the audio pipe is currently playing audio.
*/
get playing() {
if (!this.initialized) {
return false;
}
return this.audioContext.currentTime < this.nextAvailableTime;
}
}
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