Track Selection

Track types

Each playback can have three types of tracks - AUDIO , VIDEO and TEXT. These different track types are denoted using TrackVariantInfo.Type.

//VIDEO Track type
val videoTrackType = TrackVariantInfo.Type.VIDEO
//AUDIO Track Type
val audioTrackType = TrackVariantInfo.Type.AUDIO
//TEXT Track type
val textTrackType = TrackVariantInfo.Type.TEXT

Tracks

Each elementary track of each type related to the playback is represented as a TrackVariantInfo object. Each track is differentiated using bitrate, language, mimetype, etc. The metadata of the track can be obtained using the various properties of this object.

Property Name	Type	Description
id	String	The unique identifier of the track.
type	Type	The type of the track.
languageCode	String	Either a valid 2-letter ISO 639-1 language code or a normalized language code mapped to its macro-language equivalent by ExoPlayer (e.g., a 5-letter code). Note: ExoPlayer normalize language codes to ISO 639-2/T or ISO 639-2/B codes, but certain 3-letter codes are mapped to their broader macro-language equivalents. Example: Chinese (zh) Variants: cmn → zh-cmn, hsn → zh-hsn
mimeType	String	Mime Type of the option (video/mp4, video/webm, audio/mp4, audio/eac3, text/ttml, text/webvtt etc.)
bitRate	Int	The bitrate of the track (-1 if not applicable)
channelCount	Int	The number of channels of the track (-1 if not applicable)
codecs	String	The codecs used by the track (mp4a.40.2, avc1.64000D, etc.)
sampleRate	Int	The sample rate of the track (-1 if not applicable)
width	Int	The width of the track variant. Applicable only for video tracks.
height	Int	The height of the track variant. Applicable only for video tracks.
iso3LanguageCode	String	The iso3 standard language code for audio/text tracks. This code follows the 3-letter format defined by the ISO 639-2 or ISO 639-3 standard.

Available Tracks

All the available tracks of each type of track can be obtained using the availableTrackVariants API on the player. This API returns an Array of TrackVariantInfo objects.

// get all video tracks
val availableVideoTracks = player.availableTrackVariants(TrackVariantInfo.Type.VIDEO)

//get all audio tracks
val availableAudioTracks = player.availableTrackVariants(TrackVariantInfo.Type.AUDIO)

//get all subtitle tracks
val availableTextTracks = player.availableTrackVariants(TrackVariantInfo.Type.TEXT)

Get active Track

The currently active track in each type can be obtained from the Player using the activeTrackVariant API. This API returns the active track of any given Type as a TrackVariantInfo object and TrackVariantInfo.UNKNOWN if active variant is not known.

val activeSubtitleTrack = player.getActiveTrackVariant(TrackVariantInfo.Type.TEXT)

val activeAudioTrack = player.getActiveTrackVariant(TrackVariantInfo.Type.AUDIO)

val activeVideoTrack = player.getActiveTrackVariant(TrackVariantInfo.Type.VIDEO)

Set preferred Track

Any particular track can be enabled using setPreferredTrackVariant API on the player. This API takes the preferred track parameter as a TrackVariantInfo object.
Pass TrackVariantInfo.NONE to clear all existing selection preferences.

//enable first subtitle track
player.setPreferredTrackVariant(TrackVariantInfo.Type.TEXT, availableTextTracks[0])

//disable subtitles
player.setPreferredTrackVariant(TrackVariantInfo.Type.TEXT, TrackVariantInfo.NONE)

//enable first audio track
player.setPreferredTrackVariant(TrackVariantInfo.Type.AUDIO, availableAudioTracks[0])

//enable first video track
player.setPreferredTrackVariant(TrackVariantInfo.Type.VIDEO, availableVideoTracks[0])

Set maximum / minimum bitrates

Configures the Player's variant adaptation logic with the passed maximum and minimum bitrate constraints.

const val MAX_BITRATE_BPS = 780_000 // use preferred value here
const val MIN_BITRATE_BPS = 140_000 // use preferred value here

player.setPreferredBitrateThresholds(MAX_BITRATE_BPS, MIN_BITRATE_BPS)

//pass (Integer.MAX_VALUE,0) to reset any capping
player.setPreferredBitrateThresholds(Integer.MAX_VALUE, 0)

tip

Invoke the API only after the Player enters the LOADED or STARTED state.

Dolby® Atmos™

Audio MIME Types

Dolby® Atmos™ content uses the eac3-joc MIME type, which stands for Enhanced AC-3 with Joint Object Coding. The player supports multiple audio codecs with the following hierarchy:

MIME Type	Audio format
eac3-joc	Dolby® Atmos™
eac3	Dolby® Digital Plus
mp4a.40.2	Advanced Audio Coding (AAC) or Stereo

Default Preference to Dolby Atmos

By default, the player will automatically start playing in Dolby® Atmos™ if the device supports it and the stream includes it.

Retrieving Available Mime Types

To get the available audio MIME types from the player:

val availableMimeTypes = player.availableMimeType(TrackVariantInfo.Type.AUDIO)

// Example output:
// ['eac3-joc', 'eac3', 'mp4a.40.2']

If it includes 'eac3-joc', then playback supports Dolby Atmos.

Handling Mid-Stream Codec Switching

To switch between Dolby® Atmos™, Dolby® Digital Plus and Stereo using setPreferredMimeTypes which is set through API on the player. This API takes the preferred track parameter as a TrackVariantInfo object.

val preferredMimeTypes = arrayOf("eac3-joc")
player?.setPreferredMimeTypes(TrackVariantInfo.Type.AUDIO,preferredMimeTypes)

info

Support
Currently, Dolby® Atmos™ is only supported for VOD (Video on Demand) content and Smart TV's.

Best Practices

Default to Dolby Atmos:
Always set setPreferredMimeTypes to ['eac3-joc'] if Dolby® Atmos™ support is a priority for your app.