Audio

Provides basic sample playback.

We designed the Audio API to be as non-intrusive as possible, so audio will automatically stop if other audio starts playing on the device, if the device is locked, if the app / experience is backgrounded, or if headphones / bluetooth audio devices are disconnected.

Try the playlist example app (source code is on GitHub) to see an example usage of this API.

Enabling Audio

Audio is disabled by default, so your app must enable it explicitly to play sounds.

Exponent.Audio.setIsEnabled(value)

Arguments

• value (boolean) — true enables Expo Audio, and false disables it.

Returns

A Promise that will reject if audio playback could not be enabled for the device.

Playing sounds

Exponent.Audio.Sound

This class represents a sound corresponding to an Asset or URL.

Parameters

• options (object) —

  A map of options:

  • source — The source of the audio data to display. The following forms are supported:

    • A string with a network URL pointing to an audio file on the web.

    • require('path/to/file') for an audio file asset in the source code directory.

    • An Exponent.Asset object for an audio file asset.

    The iOS developer documentation lists the audio formats supported on iOS.

    The Android developer documentation lists the audio formats supported on Android.

Returns

A newly constructed instance of Exponent.Audio.Sound.

Example

const sound = new Exponent.Audio.Sound({
  source: require('./assets/sounds/hello.mp3'),
});

• soundInstance.loadAsync()

  Loads the sound into memory and prepares it for playing. This must be called before calling play.

  Returns

  A Promise that is fulfilled when the sound is loaded, or rejects if loading failed.

• soundInstance.unload()

  Unloads the sound. loadAsync must be called again in order to be able to play the sound.

• soundInstance.isLoaded()

  Returns

  A boolean that is true if and only if the sound is loaded.

• soundInstance.getDurationMillis()

  Returns

  The duration of the sound in milliseconds. This is available only after the sound is loaded.

• soundInstance.play()

  Plays the sound.

  Returns

  A Promise that is resolved, once the sound starts playing, with the status of the sound (see getStatus for details).

• soundInstance.pause()

  Pauses the sound.

  Returns

  A Promise that is resolved, once playback is paused, with the status of the sound (see getStatus for details).

• soundInstance.stop()

  Stops the sound.

  Returns

  A Promise that is resolved, once playback is stopped, with the status of the sound (see getStatus for details).

• soundInstance.setPosition(millis) Sets the playback position of the sound.

  Parameters

• millis (number) — The position to seek the sound to.

  Returns

  A Promise that is resolved, once the seek occurs, with the status of the sound (see getStatus for details).

• soundInstance.setVolume(value)

  Sets the volume of the sound. This is NOT the system volume, and will only affect this sound. This value defaults to 1.

  Parameters

  • value (number) — A number between 0 (silence) and 1 (maximum volume).

  Returns

  A Promise that is resolved, once the volume is set, with the status of the sound (see getStatus for details).

• soundInstance.setIsMuted(value)

  Sets whether the sound is muted. This is independent of the volume of the sound set in setVolume. This also does not affect the system volume, and only pertains to this sound. This value defaults to true.

  Parameters

• value (boolean) — true mutes the sound, and false unmutes it.

  Returns

  A Promise that is resolved, once the mute state is set, with the status of the sound (see getStatus for details).

• soundInstance.setIsLooping(value)

  Sets whether playback of the sound should loop. When true, it will loop indefinitely. This value defaults to false.

  Parameters

  • value (boolean) — true sets the sound to loop indefinitely.

  Returns

  A Promise that is resolved, once the loop state is set, with the status of the sound (see getStatus for details).

• soundInstance.getStatus()

  Gets the status of the sound.

  Returns

  A Promise that is resolved with the status of the sound: a dictionary with the following key-value pairs.

  • position_millis : the current position of playback in milliseconds.

  • is_playing : a boolean describing if the sound is currently playing.

  • is_muted : a boolean describing if the sound is currently muted.

  • is_looping : a boolean describing if the sound is currently looping.

• soundInstance.setStatusChangeCallback(callback)

  Sets a function to be called at regular intervals with the status of the Sound. See getStatus for details on status, and see setStatusPollingTimeoutMillis for details on the regularity with which this function is called.

  Parameters

  • callback (function) — A function taking a single parameter status (a dictionary, described in getStatus).

• soundInstance.setStatusPollingTimeoutMillis(millis)

  Sets the interval with which the status change callback is called. See setStatusChangeCallback for details on the status change callback. This value defaults to 100 milliseconds.

  Note that the status change callback will automatically be called when another call to the API for this sound completes (such as play, pause, or stop) regardless of this value.

  Parameters

  • millis (number) — The new interval between calls of the status change callback.

• soundInstance.setPlaybackFinishedCallback(callback)

  Sets a function to be called whenever this sound is finished playing to the end. This callback is not called when looping is enabled, or when the sound is stopped or paused before it finishes playing.

  Parameters

  • callback (function) — The callback receives no parameters.