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Version: 8.4.2

How to programmatically detect audio track changes

This article describes how you can use the THEOplayer API to detect audio track quality changes. An audio track "change" is triggered by enabling (or disabling) an audio track.

The AudioTrack API provides this functionality. More specifically, as a developer, you'll subscribe to the change event in the AudioTrack API.

Implementing this functionality is a common use-case for developers who want to build their own UI, and annotate the audio track that is currently active.

SDKs​

THEOplayer allows you to track audio track changes on the following SDKs.

Web SDKAndroid SDKiOS SDKtvOS SDKAndroid TV SDKChromecast SDKRoku SDK
YesYesYesYesYesYes

Implementation​

The AudioTrack API is available across all of our base SDKs. As described in the introduction, to detect text track changes, you want to detect the change event in the AudioTrack API.

Web SDK​

The implementation of the Web SDK applies to all web-based platforms, including Tizen and webOS.

The Web SDK exposes the AudioTrack API through player.audioTracks. This audioTracks property is a MediaTrackList that inherits from the TrackList. This TrackList dispatches the events from the TrackListEventMap. This TrackListEventMap contains the change event, as well as the addtrack and removetrack event.

The code below allows you to detect text track changes.

player.audioTracks.addEventListener("change", function (event) {
  const track = event.track;
  console.log(track, track.label, track.language, track.enabled);
});

The properties of a media track (e.g. enabled, language) are described in the MediaTrack API reference.

Android SDK​

The implementation of the Android SDK applies to all Android-based platforms, including Android TV and Fire TV.

The Android SDK exposes the AudioTrack API through player.getAudioTracks(). This getAudioTracks() method returns a MediaTrackList that inherits from the TrackList. This TrackList dispatches the events from the AudioTrackListEventTypes. The AudioTrackListEventTypes contains the TRACKLISTCHANGE event, as well as the ADDTRACK and REMOVETRACK event.

The code below allows you to detect audio track changes.

player.getAudioTracks().addEventListener(AudioTrackListEventTypes.TRACKLISTCHANGE, trackListChangeEvent -> {
    MediaTrack track = trackListChangeEvent.getTrack();
    System.out.println(track.getLabel() + ", " + track.getLanguage() + ", " + track.isEnabled());
});

The properties of a media track (e.g. enabled, language) are described in the MediaTrack and Track API references.

iOS/tvOS SDK and Legacy iOS/tvOS SDK (4.12.x)​

The implementation of the iOS SDK applies to all iOS-based platforms, including iPadOS and tvOS.

The iOS SDK exposes the AudioTrack API through player.audioTracks. This audioTracks property is a MediaTrackList. This MediaTrackList dispatches the events from the AudioTrackListEventTypes. The AudioTrackListEventTypes contains the CHANGE event, as well as the ADD_TRACK and REMOVE_TRACK event.

The code below allows you to detect audio track changes.

player?.audioTracks.addEventListener(type: AudioTrackListEventTypes.CHANGE, listener: { (event) in
    let track : AudioTrack = event.track as! AudioTrack
    print(track.label, track.language, track.enabled)
})

The properties of a media track (e.g. enabled, language) are described in the MediaTrack and Track API references.

Roku SDK​

This subsection is in maintenance. Reach out to our team if you need help.

Related articles

Are you reading this article because you're interested in audio tracks? Continue reading below.

Are you reading this article because you're implementing a custom UI? Then you'll find the following articles interesting: