TheAudio Output Devices API allows web applications to prompt users about what output device should be used for audio playback.

Concepts and usage

Operating systems commonly allow users to specify that audio should be played from speakers, a Bluetooth headset, or some other audio output device.This API allows applications to provide this same functionality from within a web page.

Even if allowed by a permission policy, access to a particular audio output device still requires explicit user permission, as the user may be in a location where playing audio through some output devices is not appropriate.

The API provides theMediaDevices.selectAudioOutput() method that allows users to select their desired audio output from those that are allowed by thespeaker-selection directive of thePermissions-Policy HTTP header for the document.The selected device then has user permission, allowing it to be enumerated withMediaDevices.enumerateDevices() and set as the audio output device usingHTMLMediaElement.setSinkId().

Audio devices may arbitrarily connect and disconnect.Applications that wish to react to this kind of change can listen to thedevicechange event and useenumerateDevices() to determine ifsinkId is present in the returned devices.This might trigger, for example, pausing or unpausing playback.

Interfaces

Extensions to other interfaces

The Audio Output Devices API extends the following APIs, adding the listed features:

MediaDevices

MediaDevices.selectAudioOutput()

This method prompts the user to select a specific audio output device, for example a speaker or headset.Selecting a device grants user permission to use that device and returns information about the device, including its ID.

HTMLMediaElement

HTMLMediaElement.setSinkId()

This method sets the ID of the audio device to use for output, which will be used if permitted.

HTMLMediaElement.sinkId

This property returns the unique ID of the audio device being used for output, or an empty string if the default user agent device is being used.

Security requirements

Access to the API is subject to the following constraints:

• All methods and properties may only be called in asecure context.

• MediaDevices.selectAudioOutput() grants user permission for a selected device to be used as the audio output sink:

  • Access may be gated by thespeaker-selection HTTPPermission Policy.
  • Transient user activation is required.The user has to interact with the page or a UI element for the method to be called.

• HTMLMediaElement.setSinkId() sets a permitted ID as the audio output:

  • Access may be gated by thespeaker-selection HTTPPermission Policy.
  • User permission is required to set a non-default device ID.
    • This can come from selection in the prompt launched byMediaDevices.selectAudioOutput()
    • User permission to set the output device is also implicitly granted if the user has already granted permission to use a media input device in the same group withMediaDevices.getUserMedia().

Examples

Here's an example of usingselectAudioOutput(), within a function that is triggered by a button click, and then setting the selected device as the audio output.

The code first checks ifselectAudioOutput() is supported, and if it is, uses it to select an output and return adevice ID.We then play some audio using the default output, and then callsetSinkId() in order to switch to the selected output device.

document.querySelector("#myButton").addEventListener("click", async () => {  if (!navigator.mediaDevices.selectAudioOutput) {    console.log("selectAudioOutput() not supported or not in secure context.");    return;  }  // Display prompt to select device  const audioDevice = await navigator.mediaDevices.selectAudioOutput();  // Create an audio element and start playing audio on the default device  const audio = document.createElement("audio");  audio.src = "https://example.com/audio.mp3";  audio.play();  // Change the sink to the selected audio output device.  audio.setSinkId(audioDevice.deviceId);});

Note that if you log the output details, they might look something like this:

console.log(  `${audioDevice.kind}: ${audioDevice.label} id = ${audioDevice.deviceId}`,);// audiooutput: Realtek Digital Output (Realtek(R) Audio) id = 0wE6fURSZ20H0N2NbxqgowQJLWbwo+5ablCVVJwRM3k=

Specifications

Browser compatibility

api.MediaDevices.selectAudioOutput

api.HTMLMediaElement.setSinkId

api.HTMLMediaElement.sinkId

http.headers.Permissions-Policy.speaker-selection