React Native Voice Processor

Made in Vancouver, Canada by Picovoice

The React Native Voice Processor is an asynchronous audio capture library designed for real-time audio processing on mobile devices. Given some specifications, the library delivers frames of raw audio data to the user via listeners.

Table of Contents

• React Native Voice Processor
  • Table of Contents
  • Requirements
  • Compatibility
  • Installation
  • Permissions
  • Usage
    • Capturing with Multiple Listeners
  • Example

Requirements

• Node.js (16+)
• Android SDK (21+)
• JDK (8+)
• Xcode (11+)
• CocoaPods

Compatibility

• React Native 0.68.7+
• Android 5.0+ (API 21+)
• iOS 11.0+

Installation

React Native Voice Processor is available via npm. To import it into your React Native project install with npm or yarn:

yarn add @picovoice/react-native-voice-processor

or

npm i @picovoice/react-native-voice-processor --save

Permissions

To enable recording with the hardware's microphone, you must first ensure that you have enabled the proper permission on both iOS and Android.

On iOS, open the Info.plist file and add the following line:

<key>NSMicrophoneUsageDescription</key>
<string>[Permission explanation]</string>

On Android, open the AndroidManifest.xml and add the following line:

<uses-permission android:name="android.permission.RECORD_AUDIO" />

See our example app for how to properly request this permission from your users.

Usage

Access the singleton instance of VoiceProcessor:

import {
  VoiceProcessor,
  VoiceProcessorError
} from '@picovoice/react-native-voice-processor';

let voiceProcessor = VoiceProcessor.instance;

Add listeners for audio frames and errors:

voiceProcessor.addFrameListener((frame: number[]) => {
  // use audio frame
});
voiceProcessor.addErrorListener((error: VoiceProcessorError) => {
  // handle error
});

Ask for audio record permission and start recording with the desired frame length and audio sample rate:

const frameLength = 512;
const sampleRate = 16000;

try {
  if (await voiceProcessor.hasRecordAudioPermission()) {
    await voiceProcessor.start(frameLength, sampleRate);
  } else {
    // user did not grant permission
  }
} catch (e) {
  // handle start error
}

Stop audio capture:

try {
  await this._voiceProcessor.stop();
} catch (e) {
  // handle stop error
}

Once audio capture has started successfully, any frame listeners assigned to the VoiceProcessor will start receiving audio frames with the given frameLength and sampleRate.

Capturing with Multiple Listeners

Any number of listeners can be added to and removed from the VoiceProcessor instance. However, the instance can only record audio with a single audio configuration (frameLength and sampleRate), which all listeners will receive once a call to start() has been made. To add multiple listeners:

const listener1 = (frame) => { };
const listener2 = (frame) => { };
const listeners = [listener1, listener2];
voiceProcessor.addFrameListeners(listeners);

voiceProcessor.removeFrameListeners(listeners);
// or
voiceProcessor.clearFrameListeners();

Example

The React Native Voice Processor app demonstrates how to ask for user permissions and capture output from the VoiceProcessor.

To launch the demo, run:

yarn bootstrap
yarn example ios
# or
yarn example android

Releases

v1.2.0 - August 11, 2023

• Numerous API improvements
• Error handling improvements
• Allow for multiple listeners
• Upgrades to testing infrastructure and example app

v1.1.0 - February 23, 2023

• Migrated to new template

v1.0.0 - March 29, 2021

• Initial public release