Switch subtitle tracks

Learn how to discover, switch, and disable subtitle tracks in the FastPix Android Player.

SubtitleTrack properties

Each SubtitleTrack includes:

id — pass to setSubtitleTrack(id) to switch tracks.
languageCode / languageName / label — display in your subtitle menu.
isSelected, isPlayable, isDefault, isForced — for UI state.
Optional: role, codec, groupId.

Listen for subtitle track updates

1 import io.fastpix.media3.tracks.SubtitleTrackListener
2 
3 player.addSubtitleTrackListener(object : SubtitleTrackListener {
4     override fun onSubtitlesLoaded(tracks: List<SubtitleTrack>) {
5         // Populate subtitle selection UI
6     }
7     override fun onSubtitleChange(track: SubtitleTrack?) {
8         // track == null means subtitles are disabled
9     }
10     override fun onSubtitlesLoadedFailed(error: SubtitleTrackError) {
11         // Track not found, not playable, player not ready, etc.
12     }
13     override fun onSubtitleCueChange(info: SubtitleRenderInfo) {
14         // Optional: observe cues (text + timing) if building a custom subtitle renderer
15     }
16 })

Switch subtitle track by ID

1 val subs = player.getSubtitleTracks()
2 val target = subs.firstOrNull()
3 if (target != null) {
4     player.setSubtitleTrack(target.id)
5 }

Disable subtitles

1 player.disableSubtitles()

Set a default subtitle language

Set a preferred subtitle language that applies automatically when tracks become available. This never overrides a manual selection:

1 player.setDefaultSubtitleTrack(languageName = "Spanish")

Use BCP-47 / ISO language names like "English", "Spanish", "Hindi". If the preferred language doesn’t exist in the stream, the player keeps its normal selection.

1	import io.fastpix.media3.tracks.SubtitleTrackListener
2
3	player.addSubtitleTrackListener(object : SubtitleTrackListener {
4	override fun onSubtitlesLoaded(tracks: List<SubtitleTrack>) {
5	// Populate subtitle selection UI
6	}
7	override fun onSubtitleChange(track: SubtitleTrack?) {
8	// track == null means subtitles are disabled
9	}
10	override fun onSubtitlesLoadedFailed(error: SubtitleTrackError) {
11	// Track not found, not playable, player not ready, etc.
12	}
13	override fun onSubtitleCueChange(info: SubtitleRenderInfo) {
14	// Optional: observe cues (text + timing) if building a custom subtitle renderer
15	}
16	})

1	val subs = player.getSubtitleTracks()
2	val target = subs.firstOrNull()
3	if (target != null) {
4	player.setSubtitleTrack(target.id)
5	}