mic-ts/dist/IsSilence.js

A simple stream wrapper for arecord (Linux (including Raspbian)) and sox (Mac/Windows). Returns a Passthrough stream object so that stream control like pause(), resume(), pipe(), etc. are all available.

import { Transform } from "stream";
export class IsSilence extends Transform {
    debug;
    consecSilenceCount;
    numSilenceFramesExitThresh;
    constructor(options) {
        super();
        this.debug = options.debug || false;
        this.consecSilenceCount = 0;
        this.numSilenceFramesExitThresh = 0;
    }
    getNumSilenceFramesExitThresh() {
        return this.numSilenceFramesExitThresh;
    }
    getConsecSilenceCount() {
        return this.consecSilenceCount;
    }
    setNumSilenceFramesExitThresh(numFrames) {
        this.numSilenceFramesExitThresh = numFrames;
    }
    incrConsecSilenceCount() {
        this.consecSilenceCount++;
        return this.consecSilenceCount;
    }
    resetConsecSilenceCount() {
        this.consecSilenceCount = 0;
    }
    _transform(chunk, _, callback) {
        let silenceLength = 0;
        const consecutiveSilence = this.getConsecSilenceCount();
        const numSilenceFramesExitThresh = this.getNumSilenceFramesExitThresh();
        if (numSilenceFramesExitThresh) {
            for (let i = 0; i < chunk.length; i += 2) {
                let speechSample;
                const next = chunk[i + 1];
                if (next) {
                    if (next > 128) {
                        speechSample = (next - 256) * 256;
                    }
                    else {
                        speechSample = next * 256;
                    }
                    speechSample += next;
                }
                if (speechSample && Math.abs(speechSample) > 2000) {
                    if (this.debug) {
                        console.log("Found speech block");
                    }
                    if (consecutiveSilence > numSilenceFramesExitThresh) {
                        this.emit("sound");
                    }
                    this.resetConsecSilenceCount();
                    break;
                }
                else {
                    silenceLength++;
                }
            }
            if (silenceLength === chunk.length / 2) {
                const newConsecutiveSilence = this.incrConsecSilenceCount();
                if (this.debug) {
                    console.log("Found silence block: %d of %d", newConsecutiveSilence, numSilenceFramesExitThresh);
                }
                if (newConsecutiveSilence === numSilenceFramesExitThresh) {
                    this.emit("silence");
                }
            }
        }
        this.push(chunk);
        callback();
    }
}
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