Expo Audio (expo-audio)

A library that provides an API to implement audio playback and recording in apps.

This page documents an upcoming version of the Audio library. Expo Audio is currently in alpha and subject to breaking changes.

expo-audio is a cross-platform audio library for accessing the native audio capabilities of the device.

Audio recording APIs are not available on tvOS (Apple TV).

Note that audio automatically stops if headphones/bluetooth audio devices are disconnected.

Installation

If you are installing this in an existing React Native app, start by installing expo in your project. Then, follow the additional instructions as mentioned by the library's README under "Installation in bare React Native projects" section.

Configuration in app config

You can configure expo-audio using its built-in config plugin if you use config plugins in your project (EAS Build or npx expo run:[android|ios]). The plugin allows you to configure various properties that cannot be set at runtime and require building a new app binary to take effect. If your app does not use EAS Build, then you'll need to manually configure the package.

Example app.json with config plugin

{
  "expo": {
    "plugins": [
      [
        "expo-audio",
        {
          "microphonePermission": "Allow $(PRODUCT_NAME) to access your microphone."
        }
      ]
    ]
  }
}

Configurable properties

Usage

Playing sounds

import { useEffect, useState } from 'react';
import { View, StyleSheet, Button } from 'react-native';
import { useAudioPlayer } from 'expo-audio';

export default function App() {
  const player = useAudioPlayer(audioSource);

  return (
    <View style={styles.container}>
      <Button title="Play Sound" onPress={() => player.play()} />
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    backgroundColor: '#ecf0f1',
    padding: 10,
  },
});

Recording sounds

import { useState } from 'react';
import { View, StyleSheet, Button } from 'react-native';
import { useAudioRecorder, RecordingOptions, AudioModule, RecordingPresets } from 'expo-audio';

export default function App() {
  const audioRecorder = useAudioRecorder(RecordingPresets.HIGH_QUALITY);

  const record = () => audioRecorder.record();

  const stopRecording = async () => {
    // The recording will be available on `audioRecorder.uri`.
    await audioRecorder.stop();
  };

  useEffect(() => {
    (async () => {
      const status = await AudioModule.requestRecordingPermissionsAsync();
      if (!status.granted) {
        Alert.alert('Permission to access microphone was denied');
      }
    })();
  }, []);

  return (
    <View style={styles.container}>
      <Button
        title={audioRecorder.isRecording ? 'Stop Recording' : 'Start Recording'}
        onPress={audioRecorder.isRecording ? stopRecording : record}
      />
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    backgroundColor: '#ecf0f1',
    padding: 10,
  },
});

Playing or recording audio in background 

iOS

On iOS, audio playback and recording in background is only available in standalone apps, and it requires some extra configuration. On iOS, each background feature requires a special key in UIBackgroundModes array in your Info.plist file. In standalone apps this array is empty by default, so to use background features you will need to add appropriate keys to your app.json configuration.

See an example of app.json that enables audio playback in background:

{
  "expo": {
    ...
    "ios": {
      ...
      "infoPlist": {
        ...
        "UIBackgroundModes": [
          "audio"
        ]
      }
    }
  }
}

Notes on web usage

• A MediaRecorder issue on Chrome produces WebM files missing the duration metadata. See the open Chromium issue.
• MediaRecorder encoding options and other configurations are inconsistent across browsers, utilizing a Polyfill such as kbumsik/opus-media-recorder or ai/audio-recorder-polyfill in your application will improve your experience. Any options passed to prepareToRecordAsync will be passed directly to the MediaRecorder API and as such the polyfill.
• Web browsers require sites to be served securely for them to listen to a mic. See MediaDevices getUserMedia() security for more details.

API

import { useAudioPlayer, useAudioRecorder } from 'expo-audio';

Constants

RecordingPresets.HIGH_QUALITY = {
 extension: '.m4a',
  sampleRate: 44100,
  numberOfChannels: 2,
  bitRate: 128000,
  android: {
    outputFormat: 'mpeg4',
    audioEncoder: 'aac',
  },
  ios: {
    outputFormat: IOSOutputFormat.MPEG4AAC,
    audioQuality: AudioQuality.MAX,
    linearPCMBitDepth: 16,
    linearPCMIsBigEndian: false,
    linearPCMIsFloat: false,
  },
  web: {
    mimeType: 'audio/webm',
    bitsPerSecond: 128000,
  },
};

RecordingPresets.LOW_QUALITY = {
  extension: '.m4a',
  sampleRate: 44100,
  numberOfChannels: 2,
  bitRate: 64000,
  android: {
    extension: '.3gp',
    outputFormat: '3gp',
    audioEncoder: 'amr_nb',
  },
  ios: {
    audioQuality: AudioQuality.MIN,
    outputFormat: IOSOutputFormat.MPEG4AAC,
    linearPCMBitDepth: 16,
    linearPCMIsBigEndian: false,
    linearPCMIsFloat: false,
  },
  web: {
    mimeType: 'audio/webm',
    bitsPerSecond: 128000,
  },
};

Hooks

Classes

Methods

Event Subscriptions

Interfaces

Types

Enums