node-mic/dist/audio.js

Microphone streaming library for Node.js

import { Transform } from 'stream';
export class AudioStream extends Transform {
    _debug;
    _silenceCount;
    _threshold;
    /** Number of silences before exiting. */
    get threshold() {
        return this._threshold;
    }
    set threshold(numFrames) {
        this._threshold = numFrames;
    }
    /** Number of times it has been silent. */
    get count() {
        return this._silenceCount;
    }
    /** Reset the silence count to 0. */
    resetCount() {
        this._silenceCount = 0;
    }
    constructor(options) {
        const { debug, ...transformOptions } = options;
        super(transformOptions);
        this._debug = debug || false;
        this._silenceCount = 0;
        this._threshold = 0;
    }
    _transform(chunk, encoding, callback) {
        let speechSample;
        let silenceLength = 0;
        if (this.threshold) {
            for (let i = 0; i < chunk.length; i = i + 2) {
                if (chunk[i + 1] > 128) {
                    speechSample = (chunk[i + 1] - 256) * 256;
                }
                else {
                    speechSample = chunk[i + 1] * 256;
                }
                speechSample += chunk[i];
                if (Math.abs(speechSample) > 2000) {
                    if (this._debug) {
                        console.log('Found speech block');
                    }
                    // emit 'sound' if we hear a sound after a silence
                    if (this.count > this.threshold) {
                        this.emit('sound');
                    }
                    this.resetCount();
                    break;
                }
                else {
                    silenceLength++;
                }
            }
            if (silenceLength === chunk.length / 2) {
                this._silenceCount++;
                if (this._debug) {
                    console.log('Found silence block: %d of %d', this.count, this.threshold);
                }
                // emit 'silence' only once each time the threshold condition is met
                if (this.count === this.threshold) {
                    this.emit('silence');
                }
            }
        }
        this.push(chunk);
        callback();
    }
}