How to insert subtitles?

You may be asking this question if you need captions or subtitles on your video. The sourceDescription property textTracks can be used to add an array of side-loaded text tracks to the player. All valid tracks will be available for playback as long as the player’s source is not set again. In the following guide, you will find several related topics and some code samples for different SDKs.

The textTracks property and objects can also be used for other purposes, e.g.: for including preview thumbnails and chapters. Please see linked documentation and article to find out more.

Table of Contents


Web SDK Android SDK iOS SDK tvOS SDK Android TV SDK Chromecast SDK
Yes Yes Yes
  • Can I activate captions in THEOplayer? How?
  • Can I load subtitles in several languages, for the user to choose?
  • Can I add styles to my subtitles


For builds before THEOplayer version 2.80, the feature texttrackrendering must be active on your license.

Code examples


Each text track should be described as a TextTrackDescription.

player.source = {
  sources: [
      src: "//path/to/your-manifest.m3u8", // sets source
      type: "application/x-mpegurl", // sets type - find other values at https://support.theoplayer.com/hc/en-us/articles/214350425-SourceDescription-API#TypedSource
  textTracks: [
      default: true, //optional
      kind: "subtitles", //optional - find other values at https://support.theoplayer.com/hc/en-us/articles/214350425#TextTrackDescription
      label: "English subs", //optional - this will appear in your UI
      src: "path/to/your-subs-track1.vtt",
      srclang: "en",
Android SDK
public static final SourceDescription SOURCE_WITH_SUBS =
        new SourceDescription.Builder("//path/to/your-manifest.m3u8")
                new TextTrackDescription.Builder("path/to/your-subs-track1.vtt")
iOS/tvOS SDK and Legacy iOS/tvOS SDK (4.12.x)
var sampleSource: SourceDescription {
        let src = "https://your.m3u8"
        let stream = "application/x-mpegurl"
        let textTrack1 = TextTrackDescription(src: "https://your.webvtt", srclang: "English", isDefault: true, kind: .subtitles, label:"English", format: .WebVTT)
        let textTrack2 = TextTrackDescription(src: "https://your.webvtt", srclang: "Arabic", isDefault: false, kind: .subtitles, label:"Arabic", format: .WebVTT)

        return SourceDescription(
            source: TypedSource(
                src: src,
                type: stream
            textTracks: [textTrack1,textTrack2]

Then set the source to the player by:

self.theoplayer.source = sampleSource

Subtitle styling

To style your subtitles look into the player source property textTrackStyle.

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