apple2js/js/ui/audio.ts

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import { BOOLEAN_OPTION, OptionHandler } from '../options';
import Apple2IO from '../apple2io';
import { debug } from '../util';
/*
* Audio Handling
*/
const QUANTUM_SIZE = 128;
const SAMPLE_SIZE = 1024;
const SAMPLE_RATE = 44000;
export const SOUND_ENABLED_OPTION = 'enable_sound';
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declare global {
interface Window {
webkitAudioContext: AudioContext;
}
}
const AudioContext = window.AudioContext || window.webkitAudioContext;
export class Audio implements OptionHandler {
private sound = true;
private samples: number[][] = [];
private audioContext;
private audioNode;
private workletNode: AudioWorkletNode;
private started = false;
ready: Promise<void>;
constructor(io: Apple2IO) {
this.audioContext = new AudioContext({
sampleRate: SAMPLE_RATE
});
if (window.AudioWorklet) {
this.ready = this.audioContext.audioWorklet.addModule('./dist/audio_worker.bundle.js');
this.ready
.then(() => {
this.workletNode = new AudioWorkletNode(this.audioContext, 'audio_worker');
io.sampleRate(this.audioContext.sampleRate, QUANTUM_SIZE);
io.addSampleListener((sample) => {
if (this.sound && this.audioContext.state === 'running') {
this.workletNode.port.postMessage(sample);
}
});
this.workletNode.connect(this.audioContext.destination);
})
.catch(console.error);
} else {
// TODO(flan): MDN says that createScriptProcessor is deprecated and
// replaced by AudioWorklet. FF and Chrome support AudioWorklet, but
// Safari does not (yet).
this.audioNode = this.audioContext.createScriptProcessor(SAMPLE_SIZE, 1, 1);
this.audioNode.onaudioprocess = (event) => {
const data = event.outputBuffer.getChannelData(0);
const sample = this.samples.shift();
let idx = 0;
let len = data.length;
if (sample) {
len = Math.min(sample.length, len);
for (; idx < len; idx++) {
data[idx] = sample[idx];
}
}
for (; idx < data.length; idx++) {
data[idx] = 0.0;
}
};
this.audioNode.connect(this.audioContext.destination);
io.sampleRate(this.audioContext.sampleRate, SAMPLE_SIZE);
io.addSampleListener((sample) => {
if (this.sound && this.audioContext.state === 'running') {
if (this.samples.length < 5) {
this.samples.push(sample);
}
}
});
this.ready = Promise.resolve();
}
window.addEventListener('keydown', this.autoStart);
if (window.ontouchstart !== undefined) {
window.addEventListener('touchstart', this.autoStart);
}
window.addEventListener('mousedown', this.autoStart);
debug('Sound initialized');
}
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autoStart = () => {
if (this.audioContext && !this.started) {
this.samples = [];
this.audioContext.resume().then(() => {
this.started = true;
}).catch((error) => {
console.warn('audio not started', error);
});
}
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};
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start = () => {
if (this.audioContext) {
this.samples = [];
this.audioContext.resume().catch((error) => {
console.warn('audio not resumed', error);
});
}
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};
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isEnabled = () => {
return this.sound;
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};
getOptions() {
return [
{
name: 'Audio',
options: [
{
name: SOUND_ENABLED_OPTION,
label: 'Enabled',
type: BOOLEAN_OPTION,
defaultVal: true,
}
]
}
];
}
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setOption = (name: string, value: boolean) => {
switch (name) {
case SOUND_ENABLED_OPTION:
this.sound = value;
}
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};
}