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https://github.com/Picovoice/web-voice-processor

A library for real-time voice processing in web browsers
https://github.com/Picovoice/web-voice-processor

audio-processing browser downsampling javascript microphone pcm real-time realtime speech-recognition speech-to-text voice-commands voice-processing wake-word-detection web-browser webaudio-api worker

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A library for real-time voice processing in web browsers

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README 

        
# Web Voice Processor



[![GitHub release](https://img.shields.io/github/release/Picovoice/web-voice-processor.svg)](https://github.com/Picovoice/web-voice-processor/releases)

[![GitHub](https://img.shields.io/github/license/Picovoice/web-voice-processor)](https://github.com/Picovoice/web-voice-processor/releases)

[![npm](https://img.shields.io/npm/v/@picovoice/web-voice-processor?label=npm%20%5Bweb%5D)](https://www.npmjs.com/package/@picovoice/web-voice-processor)



Made in Vancouver, Canada by [Picovoice](https://picovoice.ai)



A library for real-time voice processing in web browsers.



- Uses the [Web Audio API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API) to access microphone audio.

- Leverages [Web Workers](https://developer.mozilla.org/en-US/docs/Web/API/Worker) to offload compute-intensive tasks off of the main thread.

- Converts the microphone sampling rate to 16kHz, the _de facto_ standard for voice processing engines.

- Provides a flexible interface to pass in arbitrary voice processing workers.



- [Web Voice Processor](#web-voice-processor)

  - [Browser compatibility](#browser-compatibility)

    - [Browser features](#browser-features)

  - [Installation](#installation)

  - [How to use](#how-to-use)

    - [Via ES Modules (Create React App, Angular, Webpack, etc.)](#via-es-modules-create-react-app-angular-webpack-etc)

    - [Via HTML script tag](#via-html-script-tag)

    - [Start listening](#start-listening)

    - [Stop listening](#stop-listening)

  - [Build from source](#build-from-source)



## Browser compatibility



All modern browsers (Chrome/Edge/Opera, Firefox, Safari) are supported, including on mobile. Internet Explorer is _not_ supported.



Using the Web Audio API requires a secure context (HTTPS connection), with the exception of `localhost`, for local development.



This library includes the utility function `browserCompatibilityCheck` which can be used to perform feature detection on the current browser and return an object

indicating browser capabilities.



ESM:



```javascript

import { browserCompatibilityCheck } from '@picovoice/web-voice-processor';

browserCompatibilityCheck();

```



IIFE:



```javascript

window.WebVoiceProcessor.browserCompatibilityCheck();

```



### Browser features



- '\_picovoice' : whether all Picovoice requirements are met

- 'AudioWorklet' (not currently used; intended for the future)

- 'isSecureContext' (required for microphone permission for non-localhost)

- 'mediaDevices' (basis for microphone enumeration / access)

- 'WebAssembly' (required for all Picovoice engines)

- 'webKitGetUserMedia' (legacy predecessor to getUserMedia)

- 'Worker' (required for resampler and for all engine processing)



## Installation



```console

npm install @picovoice/web-voice-processor

```



(or)



```console

yarn add @picovoice/web-voice-processor

```



## How to use



### Via ES Modules (Create React App, Angular, Webpack, etc.)



```javascript

import { WebVoiceProcessor } from '@picovoice/web-voice-processor';

```



### Via HTML script tag



Add the following to your HTML:



```html



```



The IIFE version of the library adds `WebVoiceProcessor` to the `window` global scope.



### Start listening



WebVoiceProcessor follows the subscribe/unsubscribe pattern. WebVoiceProcessor

will automatically start recording audio as soon as an engine is subscribed.



```javascript

const worker = new Worker('${WORKER_PATH}');

const engine = {

  onmessage: function(e) {

    /// ... handle inputFrame

  }

}



await WebVoiceProcessor.subscribe(engine);

await WebVoiceProcessor.subscribe(worker);

// or

await WebVoiceProcessor.subscribe([engine, worker]);

```



An `engine` is either a [Web Workers](https://developer.mozilla.org/en-US/docs/Web/API/Worker) or an object

implementing the following interface within their `onmessage` method:



```javascript

onmessage = function (e) {

    switch (e.data.command) {

        case 'process':

            process(e.data.inputFrame);

            break;

    }

};

```



where `e.data.inputFrame` is an `Int16Array` of `frameLength` audio samples.



For examples of using engines, look at [src/engines](src/engines).



This is async due to its [Web Audio API microphone request](https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia). The promise will be rejected if the user refuses permission, no suitable devices are found, etc. Your calling code should anticipate the possibility of rejection. When the promise resolves, the WebVoiceProcessor is running.



### Stop Listening



Unsubscribing the engines initially subscribed will stop audio recorder.



```javascript

await WebVoiceProcessor.unsubscribe(engine);

await WebVoiceProcessor.unsubscribe(worker);

//or

await WebVoiceProcessor.unsubscribe([engine, worker]);

```



### Reset



Use the `reset` function to remove all engines and stop recording audio.



```javascript

await WebVoiceProcessor.reset();

```



### Options



To update the audio settings in `WebVoiceProcessor`, use the `setOptions` function:



```javascript

// Override default options

let options = {

  frameLength: 512,

  outputSampleRate: 16000,

  deviceId: null,

  filterOrder: 50,

};



WebVoiceProcessor.setOptions(options);

```



### Custom Recorder Processor



**NOTE**: Issues related to custom recorder processor implementations are out of the scope of this repo.



Take a look at [recorder_processor.js](src/audio_worklet/recorder_processor.js) in this repo as a reference

on how to create a simple recorder processor. To learn more about creating a recorder processor,

check out [AudioWorkletProcessor](https://developer.mozilla.org/en-US/docs/Web/API/AudioWorkletProcessor) docs.



Add the option `customRecorderProcessorURL` to options object to use your own recorder processor.

Enter the string to the custom recorder processor URL or leave it blank to use the default recorder processor.



```javascript

// Override default options

let options = {

  frameLength: 512,

  outputSampleRate: 16000,

  deviceId: null,

  filterOrder: 50,

  customRecorderProcessorURL: "${URL_PATH_TO_RECORDER_PROCESSOR}"

};



WebVoiceProcessor.setOptions(options);

```



### VuMeter



`WebVoiceProcessor` includes a built-in engine which returns the [VU meter](https://en.wikipedia.org/wiki/VU_meter).

To capture the VU meter value, create a VuMeterEngine instance and subscribe it to the engine:



```javascript

function vuMeterCallback(dB) {

  console.log(dB)

}



const vuMeterEngine = new VuMeterEngine(vuMeterCallback);

WebVoiceProcessor.subscribe(vuMeterEngine);

```



The `vuMeterCallback` should expected a number in terms of [dBFS](https://en.wikipedia.org/wiki/DBFS) within the range of [-96, 0].



## Build from source



Use `yarn` or `npm` to build WebVoiceProcessor:



```console

yarn

yarn build

```



(or)



```console

npm install

npm run-script build

```



The build script outputs minified and non-minified versions of the IIFE and ESM formats to the `dist` folder. It also will output the TypeScript type definitions.