Expo Audio (expo-av)A library that provides an API to implement audio playback and recording in apps.
TheAudiocomponent fromexpo-avdocumented on this page will be replaced by an improved version inexpo-audioin an upcoming release when the new library is stable. Learn aboutexpo-audio.
Audio from expo-av allows you to implement audio playback and recording in your app.
Audio recording APIs are not available on tvOS (Apple TV).
Note that audio automatically stops if headphones/bluetooth audio devices are disconnected.
See the playlist example app for an example on the media playback API, and the recording example app for an example of the recording API.
Installation
- npx expo install expo-avIf 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.
Usage
Playing sounds
import { useEffect, useState } from 'react';
import { View, StyleSheet, Button } from 'react-native';
import { Audio } from 'expo-av';
export default function App() {
const [sound, setSound] = useState();
async function playSound() {
console.log('Loading Sound');
const { sound } = await Audio.Sound.createAsync( require('./assets/Hello.mp3')
);
setSound(sound);
console.log('Playing Sound');
await sound.playAsync();
}
useEffect(() => {
return sound
? () => {
console.log('Unloading Sound');
sound.unloadAsync();
}
: undefined;
}, [sound]);
return (
<View style={styles.container}>
<Button title="Play Sound" onPress={playSound} />
</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 { Audio } from 'expo-av';
export default function App() {
const [recording, setRecording] = useState();
const [permissionResponse, requestPermission] = Audio.usePermissions();
async function startRecording() {
try {
if (permissionResponse.status !== 'granted') {
console.log('Requesting permission..');
await requestPermission();
}
await Audio.setAudioModeAsync({
allowsRecordingIOS: true,
playsInSilentModeIOS: true,
});
console.log('Starting recording..');
const { recording } = await Audio.Recording.createAsync( Audio.RecordingOptionsPresets.HIGH_QUALITY
);
setRecording(recording);
console.log('Recording started');
} catch (err) {
console.error('Failed to start recording', err);
}
}
async function stopRecording() {
console.log('Stopping recording..');
setRecording(undefined);
await recording.stopAndUnloadAsync();
await Audio.setAudioModeAsync(
{
allowsRecordingIOS: false,
}
);
const uri = recording.getURI();
console.log('Recording stopped and stored at', uri);
}
return (
<View style={styles.container}>
<Button
title={recording ? 'Stop Recording' : 'Start Recording'}
onPress={recording ? stopRecording : startRecording}
/>
</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
prepareToRecordAsyncwill 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 { Audio } from 'expo-av';
Constants
Type: Record<string, RecordingOptions>
Constant which contains definitions of the two preset examples of RecordingOptions, as implemented in the Audio SDK.
HIGH_QUALITY
RecordingOptionsPresets.HIGH_QUALITY = {
isMeteringEnabled: true,
android: {
extension: '.m4a',
outputFormat: AndroidOutputFormat.MPEG_4,
audioEncoder: AndroidAudioEncoder.AAC,
sampleRate: 44100,
numberOfChannels: 2,
bitRate: 128000,
},
ios: {
extension: '.m4a',
outputFormat: IOSOutputFormat.MPEG4AAC,
audioQuality: IOSAudioQuality.MAX,
sampleRate: 44100,
numberOfChannels: 2,
bitRate: 128000,
linearPCMBitDepth: 16,
linearPCMIsBigEndian: false,
linearPCMIsFloat: false,
},
web: {
mimeType: 'audio/webm',
bitsPerSecond: 128000,
},
};
LOW_QUALITY
RecordingOptionsPresets.LOW_QUALITY = {
isMeteringEnabled: true,
android: {
extension: '.3gp',
outputFormat: AndroidOutputFormat.THREE_GPP,
audioEncoder: AndroidAudioEncoder.AMR_NB,
sampleRate: 44100,
numberOfChannels: 2,
bitRate: 128000,
},
ios: {
extension: '.caf',
audioQuality: IOSAudioQuality.MIN,
sampleRate: 44100,
numberOfChannels: 2,
bitRate: 128000,
linearPCMBitDepth: 16,
linearPCMIsBigEndian: false,
linearPCMIsFloat: false,
},
web: {
mimeType: 'audio/webm',
bitsPerSecond: 128000,
},
};
Hooks
| Parameter | Type |
|---|---|
| options(optional) | PermissionHookOptions<object> |
Check or request permissions to record audio.
This uses both requestPermissionAsync and getPermissionsAsync to interact with the permissions.
[null | PermissionResponse, RequestPermissionMethod<PermissionResponse>, GetPermissionMethod<PermissionResponse>]Example
const [permissionResponse, requestPermission] = Audio.usePermissions();
Classes
Warning: Experimental for web.
This class represents an audio recording. After creating an instance of this class, prepareToRecordAsync
must be called in order to record audio. Once recording is finished, call stopAndUnloadAsync. Note that
only one recorder is allowed to exist in the state between prepareToRecordAsync and stopAndUnloadAsync
at any given time.
Note that your experience must request audio recording permissions in order for recording to function.
See the Permissions module for more details.
Additionally, audio recording is not supported in the iOS Simulator.
A newly constructed instance of Audio.Recording.
Example
const recording = new Audio.Recording();
try {
await recording.prepareToRecordAsync(Audio.RecordingOptionsPresets.HIGH_QUALITY);
await recording.startAsync();
// You are now recording!
} catch (error) {
// An error occurred!
}
Recording Methods
| Parameter | Type | Description |
|---|---|---|
| options(optional) | RecordingOptions | Options for the recording, including sample rate, bitrate, channels, format, encoder, and extension. If no options are passed to,
the recorder will be created with options Default: RecordingOptionsPresets.LOW_QUALITY |
| onRecordingStatusUpdate(optional) | null | (status: RecordingStatus) => void | A function taking a single parameter Default: null |
| progressUpdateIntervalMillis(optional) | null | number | The interval between calls of Default: null |
Creates and starts a recording using the given options, with optional onRecordingStatusUpdate and progressUpdateIntervalMillis.
const { recording, status } = await Audio.Recording.createAsync(
options,
onRecordingStatusUpdate,
progressUpdateIntervalMillis
);
// Which is equivalent to the following:
const recording = new Audio.Recording();
await recording.prepareToRecordAsync(options);
recording.setOnRecordingStatusUpdate(onRecordingStatusUpdate);
await recording.startAsync();
Promise<RecordingObject>A Promise that is rejected if creation failed, or fulfilled with the following dictionary if creation succeeded.
Example
try {
const { recording: recordingObject, status } = await Audio.Recording.createAsync(
Audio.RecordingOptionsPresets.HIGH_QUALITY
);
// You are now recording!
} catch (error) {
// An error occurred!
}
Deprecated Use
createNewLoadedSoundAsync()instead.
| Parameter | Type |
|---|---|
| initialStatus(optional) | AVPlaybackStatusToSet |
| onPlaybackStatusUpdate(optional) | null | (status: AVPlaybackStatus) => void |
Promise<SoundObject>| Parameter | Type | Description |
|---|---|---|
| initialStatus(optional) | AVPlaybackStatusToSet | The initial intended Default: {} |
| onPlaybackStatusUpdate(optional) | null | (status: AVPlaybackStatus) => void | A function taking a single parameter Default: null |
Creates and loads a new Sound object to play back the Recording. Note that this will only succeed once the Recording
is done recording and stopAndUnloadAsync() has been called.
Promise<SoundObject>A Promise that is rejected if creation failed, or fulfilled with the SoundObject.
Returns a list of available recording inputs. This method can only be called if the Recording has been prepared.
Promise<RecordingInput[]>A Promise that is fulfilled with an array of RecordingInput objects.
Returns the currently-selected recording input. This method can only be called if the Recording has been prepared.
Promise<RecordingInput>A Promise that is fulfilled with a RecordingInput object.
Gets the status of the Recording.
Promise<RecordingStatus>A Promise that is resolved with the RecordingStatus object.
Gets the local URI of the Recording. Note that this will only succeed once the Recording is prepared
to record. On web, this will not return the URI until the recording is finished.
null | stringA string with the local URI of the Recording, or null if the Recording is not prepared
to record (or, on Web, if the recording has not finished).
Pauses recording. This method can only be called if the Recording has been prepared.
This is only available on Android API version 24 and later.
Promise<RecordingStatus>A Promise that is fulfilled when recording has paused, or rejects if recording could not be paused.
If the Android API version is less than 24, the Promise will reject. The promise is resolved with the
RecordingStatus of the recording.
| Parameter | Type | Description |
|---|---|---|
| options(optional) | RecordingOptions |
Default: RecordingOptionsPresets.LOW_QUALITY |
Loads the recorder into memory and prepares it for recording. This must be called before calling startAsync().
This method can only be called if the Recording instance has never yet been prepared.
Promise<RecordingStatus>A Promise that is fulfilled when the recorder is loaded and prepared, or rejects if this failed. If another Recording exists
in your experience that is currently prepared to record, the Promise will reject. If the RecordingOptions provided are invalid,
the Promise will also reject. The promise is resolved with the RecordingStatus of the recording.
| Parameter | Type | Description |
|---|---|---|
| inputUid | string | The uid of a |
Sets the current recording input.
Promise<void>A Promise that is resolved if successful or rejected if not.
| Parameter | Type | Description |
|---|---|---|
| onRecordingStatusUpdate | null | (status: RecordingStatus) => void | A function taking a single parameter |
Sets a function to be called regularly with the RecordingStatus of the Recording.
onRecordingStatusUpdate will be called when another call to the API for this recording completes (such as prepareToRecordAsync(),
startAsync(), getStatusAsync(), or stopAndUnloadAsync()), and will also be called at regular intervals while the recording can record.
Call setProgressUpdateInterval() to modify the interval with which onRecordingStatusUpdate is called while the recording can record.
void| Parameter | Type | Description |
|---|---|---|
| progressUpdateIntervalMillis | number | The new interval between calls of |
Sets the interval with which onRecordingStatusUpdate is called while the recording can record.
See setOnRecordingStatusUpdate for details. This value defaults to 500 milliseconds.
voidBegins recording. This method can only be called if the Recording has been prepared.
Promise<RecordingStatus>A Promise that is fulfilled when recording has begun, or rejects if recording could not be started.
The promise is resolved with the RecordingStatus of the recording.
Stops the recording and deallocates the recorder from memory. This reverts the Recording instance
to an unprepared state, and another Recording instance must be created in order to record again.
This method can only be called if the Recording has been prepared.
On Android this method may fail with
E_AUDIO_NODATAwhen called too soon afterstartAsyncand no audio data has been recorded yet. In that case the recorded file will be invalid and should be discarded.
Promise<RecordingStatus>A Promise that is fulfilled when recording has stopped, or rejects if recording could not be stopped.
The promise is resolved with the RecordingStatus of the recording.
Type: Class implements Playback
This class represents a sound corresponding to an Asset or URL.
A newly constructed instance of Audio.Sound.
Example
const sound = new Audio.Sound();
try {
await sound.loadAsync(require('./assets/sounds/hello.mp3'));
await sound.playAsync();
// Your sound is playing!
// Don't forget to unload the sound from memory
// when you are done using the Sound object
await sound.unloadAsync();
} catch (error) {
// An error occurred!
}
Method not described below and the rest of the API for
Audio.Soundis the same as the imperative playback API forVideo. See the AV documentation for further information.
Sound Methods
Deprecated Use
Sound.createAsync()instead
| Parameter | Type |
|---|---|
| source | AVPlaybackSource |
| initialStatus(optional) | AVPlaybackStatusToSet |
| onPlaybackStatusUpdate(optional) | null | (status: AVPlaybackStatus) => void |
| downloadFirst(optional) | boolean |
Promise<SoundObject>| Parameter | Type | Description |
|---|---|---|
| source | AVPlaybackSource | The source of the sound. See the AV documentation for details on the possible |
| initialStatus(optional) | AVPlaybackStatusToSet | The initial intended Default: {} |
| onPlaybackStatusUpdate(optional) | null | (status: AVPlaybackStatus) => void | A function taking a single parameter Default: null |
| downloadFirst(optional) | boolean | If set to true, the system will attempt to download the resource to the device before loading. This value defaults to Default: true |
Creates and loads a sound from source.
const { sound } = await Audio.Sound.createAsync(
source,
initialStatus,
onPlaybackStatusUpdate,
downloadFirst
);
// Which is equivalent to the following:
const sound = new Audio.Sound();
sound.setOnPlaybackStatusUpdate(onPlaybackStatusUpdate);
await sound.loadAsync(source, initialStatus, downloadFirst);
Promise<SoundObject>A Promise that is rejected if creation failed, or fulfilled with the SoundObject if creation succeeded.
Example
try {
const { sound: soundObject, status } = await Audio.Sound.createAsync(
require('./assets/sounds/hello.mp3'),
{ shouldPlay: true }
);
// Your sound is playing!
} catch (error) {
// An error occurred!
}
| Parameter | Type | Description |
|---|---|---|
| callback | AudioSampleCallback | A function taking the |
Sets a function to be called during playback, receiving the audio sample as parameter.
void| Parameter | Type | Description |
|---|---|---|
| onMetadataUpdate | (metadata: AVMetadata) => void | A function taking a single object of type |
Sets a function to be called whenever the metadata of the sound object changes, if one is set.
void| Parameter | Type | Description |
|---|---|---|
| onPlaybackStatusUpdate | null | (status: AVPlaybackStatus) => void | A function taking a single parameter |
Sets a function to be called regularly with the AVPlaybackStatus of the playback object.
onPlaybackStatusUpdate will be called whenever a call to the API for this playback object completes
(such as setStatusAsync(), getStatusAsync(), or unloadAsync()), nd will also be called at regular intervals
while the media is in the loaded state.
Set progressUpdateIntervalMillis via setStatusAsync() or setProgressUpdateIntervalAsync() to modify
the interval with which onPlaybackStatusUpdate is called while loaded.
voidMethods
Checks user's permissions for audio recording.
Promise<PermissionResponse>A promise that resolves to an object of type PermissionResponse.
Asks the user to grant permissions for audio recording.
Promise<PermissionResponse>A promise that resolves to an object of type PermissionResponse.
We provide this API to customize the audio experience on iOS and Android.
Promise<void>A Promise that will reject if the audio mode could not be enabled for the device.
| Parameter | Type | Description |
|---|---|---|
| value | boolean |
|
Audio is enabled by default, but if you want to write your own Audio API in a bare workflow app, you might want to disable the Audio API.
Promise<void>A Promise that will reject if audio playback could not be enabled for the device.
Interfaces
An object obtained by permissions get and request functions.
| Property | Type | Description |
|---|---|---|
| canAskAgain | boolean | Indicates if user can be asked again for specific permission. If not, one should be directed to the Settings app in order to enable/disable the permission. |
| expires | PermissionExpiration | Determines time when the permission expires. |
| granted | boolean | A convenience boolean that indicates if the permission is granted. |
| status | PermissionStatus | Determines the status of the permission. |
Types
| Property | Type | Description |
|---|---|---|
| frames | number[] | All samples for this specific Audio Channel in PCM Buffer format (-1 to 1). |
| Property | Type | Description |
|---|---|---|
| allowsRecordingIOS(optional) | boolean | A boolean selecting if recording is enabled on iOS.
Default: false |
| interruptionModeAndroid | InterruptionModeAndroid | An enum selecting how your experience's audio should interact with the audio from other apps on Android. |
| interruptionModeIOS | InterruptionModeIOS | An enum selecting how your experience's audio should interact with the audio from other apps on iOS. |
| playsInSilentModeIOS(optional) | boolean | A boolean selecting if your experience's audio should play in silent mode on iOS. Default: false |
| playThroughEarpieceAndroid(optional) | boolean | A boolean selecting if the audio is routed to earpiece on Android. Default: false |
| shouldDuckAndroid(optional) | boolean | A boolean selecting if your experience's audio should automatically be lowered in volume ("duck") if audio from another
app interrupts your experience. If Default: true |
| staysActiveInBackground(optional) | boolean | A boolean selecting if the audio session (playback or recording) should stay active even when the app goes into background.
Default: false |
Object passed to the onAudioSampleReceived function. Represents a single sample from an audio source.
The sample contains all frames (PCM Buffer values) for each channel of the audio, so if the audio is stereo (interleaved),
there will be two channels, one for left and one for right audio.
| Property | Type | Description |
|---|---|---|
| channels | AudioChannel[] | An array representing the data from each channel in PCM Buffer format. Array elements are objects in the following format: |
| timestamp | number | A number representing the timestamp of the current sample in seconds, relative to the audio track's timeline.
|
Type: null or object shaped as below:
(sample) => void
void| Parameter | Type | Description |
|---|---|---|
| sample(index signature) | AudioSample | - |
Literal Type: multiple types
Acceptable values are: PermissionHookBehavior | Options
| Property | Type | Description |
|---|---|---|
| recording | Recording | The newly created and started |
| status | RecordingStatus | The |
The recording extension, sample rate, bitrate, channels, format, encoder, etc. which can be customized by passing options to prepareToRecordAsync().
We provide the following preset options for convenience, as used in the example above. See below for the definitions of these presets.
Audio.RecordingOptionsPresets.HIGH_QUALITYAudio.RecordingOptionsPresets.LOW_QUALITY
We also provide the ability to define your own custom recording options, but we recommend you use the presets,
as not all combinations of options will allow you to successfully prepareToRecordAsync().
You will have to test your custom options on iOS and Android to make sure it's working. In the future,
we will enumerate all possible valid combinations, but at this time, our goal is to make the basic use-case easy (with presets)
and the advanced use-case possible (by exposing all the functionality available on all supported platforms).
| Property | Type | Description |
|---|---|---|
| android | RecordingOptionsAndroid | Recording options for the Android platform. |
| ios | RecordingOptionsIOS | Recording options for the iOS platform. |
| isMeteringEnabled(optional) | boolean | A boolean that determines whether audio level information will be part of the status object under the "metering" key. |
| keepAudioActiveHint(optional) | boolean | A boolean that hints to keep the audio active after |
| web | RecordingOptionsWeb | Recording options for the Web platform. |
| Property | Type | Description |
|---|---|---|
| audioEncoder | AndroidAudioEncoder | number | The desired audio encoder. See the |
| bitRate(optional) | number | The desired bit rate. Note that Example
|
| extension | string | The desired file extension. Example valid values are |
| maxFileSize(optional) | number | The desired maximum file size in bytes, after which the recording will stop (but Example
|
| numberOfChannels(optional) | number | The desired number of channels. Note that Example
|
| outputFormat | AndroidOutputFormat | number | The desired file format. See the |
| sampleRate(optional) | number | The desired sample rate. Note that the sampling rate depends on the format for the audio recording, as well as the capabilities of the platform. For instance, the sampling rate supported by AAC audio coding standard ranges from 8 to 96 kHz, the sampling rate supported by AMRNB is 8kHz, and the sampling rate supported by AMRWB is 16kHz. Please consult with the related audio coding standard for the supported audio sampling rate. Example 44100 |
| Property | Type | Description |
|---|---|---|
| audioQuality | IOSAudioQuality | number | The desired audio quality. See the |
| bitDepthHint(optional) | number | The desired bit depth hint. Example
|
| bitRate | number | The desired bit rate. Example
|
| bitRateStrategy(optional) | number | The desired bit rate strategy. See the next section for an enumeration of all valid values of |
| extension | string | The desired file extension. Example
|
| linearPCMBitDepth(optional) | number | The desired PCM bit depth. Example
|
| linearPCMIsBigEndian(optional) | boolean | A boolean describing if the PCM data should be formatted in big endian. |
| linearPCMIsFloat(optional) | boolean | A boolean describing if the PCM data should be encoded in floating point or integral values. |
| numberOfChannels | number | The desired number of channels. Example
|
| outputFormat(optional) | string | IOSOutputFormat | number | The desired file format. See the |
| sampleRate | number | The desired sample rate. Example
|
| Property | Type | Description |
|---|---|---|
| bitsPerSecond(optional) | number | - |
| mimeType(optional) | string | - |
TODO: For consistency with PlaybackStatus, should we include progressUpdateIntervalMillis here as well?
| Property | Type | Description |
|---|---|---|
| canRecord | boolean | Only for: Android iOS A boolean describing if the |
| durationMillis | number | Only for: Android iOS The current duration of the recorded audio or the final duration is the recording has been stopped. |
| isDoneRecording | boolean | Only for: Android iOS A boolean describing if the |
| isRecording | boolean | Only for: Android iOS A boolean describing if the |
| mediaServicesDidReset(optional) | boolean | Only for: iOS A boolean indicating whether media services were reset during recording. This may occur if the active input ceases to be available during recording. For example: airpods are the active input and they run out of batteries during recording. |
| metering(optional) | number | Only for: Android iOS A number that's the most recent reading of the loudness in dB. The value ranges from |
| uri(optional) | string | null | - |
| Property | Type | Description |
|---|---|---|
| sound | Sound | The newly created and loaded |
| status | AVPlaybackStatus | The |
Enums
InterruptionModeAndroid.DoNotMix ＝ 1If this option is set, your experience's audio interrupts audio from other apps.
InterruptionModeIOS.MixWithOthers ＝ 0This is the default option. If this option is set, your experience's audio is mixed with audio playing in background apps.
InterruptionModeIOS.DoNotMix ＝ 1If this option is set, your experience's audio interrupts audio from other apps.
Note Not all of the iOS formats included in this list of constants are currently supported by iOS, in spite of appearing in the Apple source code. For an accurate list of formats supported by iOS, see Core Audio Codecs and iPhone Audio File Formats.
Check official Apple documentation for more information.
Unified API
The rest of the API on the Sound.Audio is the same as the API for Video component ref. See the AV documentation for more information.