ExoTrackSelection


@UnstableApi
interface ExoTrackSelection : TrackSelection

Known direct subclasses
BaseTrackSelection

An abstract base class suitable for most ExoTrackSelection implementations.

FakeTrackSelection

A fake ExoTrackSelection that only returns 1 fixed track, and allows querying the number of calls to its methods.

Known indirect subclasses
AdaptiveTrackSelection

A bandwidth based adaptive ExoTrackSelection, whose selected track is updated to be the one of highest quality given the current network conditions and the state of the buffer.

FixedTrackSelection

A TrackSelection consisting of a single track.

RandomTrackSelection

An ExoTrackSelection whose selected track is updated randomly.


A TrackSelection that can change the individually selected track as a result of calling updateSelectedTrack or evaluateQueueSize. This only happens between calls to enable and disable.

Summary

Nested types

Contains of a subset of selected tracks belonging to a TrackGroup.

Factory for ExoTrackSelection instances.

Public functions

Unit

Disables this track selection.

Unit

Enables the track selection.

Int
evaluateQueueSize(
    playbackPositionUs: Long,
    queue: (Mutable)List<MediaChunk!>!
)

Returns the number of chunks that should be retained in the queue.

Boolean
excludeTrack(index: Int, exclusionDurationMs: Long)

Attempts to exclude the track at the specified index in the selection, making it ineligible for selection by calls to updateSelectedTrack for the specified period of time.

Long

Returns the most recent bitrate estimate utilised for track selection.

Format!

Returns the Format of the individual selected track.

Int

Returns the index of the selected track.

Int

Returns the index in the track group of the individual selected track.

Any?

Returns optional data associated with the current track selection.

Int

Returns the reason for the current track selection.

Boolean
isTrackExcluded(index: Int, nowMs: Long)

Returns whether the track at the specified index in the selection is excluded.

Unit

Called to notify the selection of a position discontinuity.

Unit

Called to notify when the playback is paused or resumed.

Unit
onPlaybackSpeed(playbackSpeed: Float)

Called to notify the selection of the current playback speed.

Unit

Called to notify when a rebuffer occurred.

Boolean
shouldCancelChunkLoad(
    playbackPositionUs: Long,
    loadingChunk: Chunk!,
    queue: (Mutable)List<MediaChunk!>!
)

Returns whether an ongoing load of a chunk should be canceled.

Unit
updateSelectedTrack(
    playbackPositionUs: Long,
    bufferedDurationUs: Long,
    availableDurationUs: Long,
    queue: (Mutable)List<MediaChunk!>!,
    mediaChunkIterators: Array<MediaChunkIterator!>!
)

Updates the selected track for sources that load media in discrete MediaChunks.

Inherited Constants

From androidx.media3.exoplayer.trackselection.TrackSelection
const Int

The first value that can be used for application specific track selection types.

const Int

An unspecified track selection type.

Inherited functions

From androidx.media3.exoplayer.trackselection.TrackSelection
Format!
getFormat(index: Int)

Returns the format of the track at a given index in the selection.

Int

Returns the index in the track group of the track at a given index in the selection.

TrackGroup!

Returns the TrackGroup to which the selected tracks belong.

Int

Returns an integer specifying the type of the selection, or TYPE_UNSET if not specified.

Int
indexOf(format: Format!)

Returns the index in the selection of the track with the specified format.

Int
indexOf(indexInTrackGroup: Int)

Returns the index in the selection of the track with the specified index in the track group.

Int

Returns the number of tracks in the selection.

Public functions

disable

fun disable(): Unit

Disables this track selection. No further dynamic changes via updateSelectedTrack, evaluateQueueSize or shouldCancelChunkLoad will happen after this call.

This method may only be called when the track selection is already enabled.

enable

fun enable(): Unit

Enables the track selection. Dynamic changes via updateSelectedTrack, evaluateQueueSize or shouldCancelChunkLoad will only happen after this call.

This method may not be called when the track selection is already enabled.

evaluateQueueSize

fun evaluateQueueSize(
    playbackPositionUs: Long,
    queue: (Mutable)List<MediaChunk!>!
): Int

Returns the number of chunks that should be retained in the queue.

May be called by sources that load media in discrete MediaChunks and support discarding of buffered chunks.

To avoid excessive re-buffering, implementations should normally return the size of the queue. An example of a case where a smaller value may be returned is if network conditions have improved dramatically, allowing chunks to be discarded and re-buffered in a track of significantly higher quality. Discarding chunks may allow faster switching to a higher quality track in this case.

Note that even if the source supports discarding of buffered chunks, the actual number of discarded chunks is not guaranteed. The source will call updateSelectedTrack with the updated queue of chunks before loading a new chunk to allow switching to another quality.

This method will only be called when the selection is enabled and none of the MediaChunks in the queue are currently loading.

Parameters
playbackPositionUs: Long

The current playback position in microseconds. If playback of the period to which this track selection belongs has not yet started, the value will be the starting position in the period minus the duration of any media in previous periods still to be played.

queue: (Mutable)List<MediaChunk!>!

The queue of buffered MediaChunks. Must not be modified.

Returns
Int

The number of chunks to retain in the queue.

excludeTrack

fun excludeTrack(index: Int, exclusionDurationMs: Long): Boolean

Attempts to exclude the track at the specified index in the selection, making it ineligible for selection by calls to updateSelectedTrack for the specified period of time.

Exclusion will fail if all other tracks are currently excluded. If excluding the currently selected track, note that it will remain selected until the next call to updateSelectedTrack.

This method will only be called when the selection is enabled.

Parameters
index: Int

The index of the track in the selection.

exclusionDurationMs: Long

The duration of time for which the track should be excluded, in milliseconds.

Returns
Boolean

Whether exclusion was successful.

getLatestBitrateEstimate

fun getLatestBitrateEstimate(): Long

Returns the most recent bitrate estimate utilised for track selection.

The default behavior is to return RATE_UNSET_INT, indicating that the bitrate estimate was not computed for the track selection decision.

getSelectedFormat

fun getSelectedFormat(): Format!

Returns the Format of the individual selected track.

getSelectedIndex

fun getSelectedIndex(): Int

Returns the index of the selected track.

getSelectedIndexInTrackGroup

fun getSelectedIndexInTrackGroup(): Int

Returns the index in the track group of the individual selected track.

getSelectionData

fun getSelectionData(): Any?

Returns optional data associated with the current track selection.

getSelectionReason

@C.SelectionReason
fun getSelectionReason(): Int

Returns the reason for the current track selection.

isTrackExcluded

fun isTrackExcluded(index: Int, nowMs: Long): Boolean

Returns whether the track at the specified index in the selection is excluded.

Parameters
index: Int

The index of the track in the selection.

nowMs: Long

The current time in the timebase of elapsedRealtime.

onDiscontinuity

fun onDiscontinuity(): Unit

Called to notify the selection of a position discontinuity.

This happens when the playback position jumps, e.g., as a result of a seek being performed.

onPlayWhenReadyChanged

fun onPlayWhenReadyChanged(playWhenReady: Boolean): Unit

Called to notify when the playback is paused or resumed.

Parameters
playWhenReady: Boolean

Whether playback will proceed when ready.

onPlaybackSpeed

fun onPlaybackSpeed(playbackSpeed: Float): Unit

Called to notify the selection of the current playback speed. The playback speed may affect adaptive track selection.

Parameters
playbackSpeed: Float

The factor by which playback is sped up.

onRebuffer

fun onRebuffer(): Unit

Called to notify when a rebuffer occurred.

A rebuffer is defined to be caused by buffer depletion rather than a user action. Hence this method is not called during initial buffering or when buffering as a result of a seek operation.

shouldCancelChunkLoad

fun shouldCancelChunkLoad(
    playbackPositionUs: Long,
    loadingChunk: Chunk!,
    queue: (Mutable)List<MediaChunk!>!
): Boolean

Returns whether an ongoing load of a chunk should be canceled.

May be called by sources that load media in discrete MediaChunks and support canceling the ongoing chunk load. The ongoing chunk load is either the last in the queue or another type of Chunk, for example, if the source loads initialization or encryption data.

To avoid excessive re-buffering, implementations should normally return false. An example where true might be returned is if a load of a high quality chunk gets stuck and canceling this load in favor of a lower quality alternative may avoid a rebuffer.

The source will call evaluateQueueSize after the cancelation finishes to allow discarding of chunks, and updateSelectedTrack before loading a new chunk to allow switching to another quality.

This method will only be called when the selection is enabled.

Parameters
playbackPositionUs: Long

The current playback position in microseconds. If playback of the period to which this track selection belongs has not yet started, the value will be the starting position in the period minus the duration of any media in previous periods still to be played.

loadingChunk: Chunk!

The currently loading Chunk that will be canceled if this method returns true.

queue: (Mutable)List<MediaChunk!>!

The queue of buffered MediaChunks, including the loadingChunk if it's a MediaChunk. Must not be modified.

Returns
Boolean

Whether the ongoing load of loadingChunk should be canceled.

updateSelectedTrack

fun updateSelectedTrack(
    playbackPositionUs: Long,
    bufferedDurationUs: Long,
    availableDurationUs: Long,
    queue: (Mutable)List<MediaChunk!>!,
    mediaChunkIterators: Array<MediaChunkIterator!>!
): Unit

Updates the selected track for sources that load media in discrete MediaChunks.

This method will only be called when the selection is enabled.

Parameters
playbackPositionUs: Long

The current playback position in microseconds. If playback of the period to which this track selection belongs has not yet started, the value will be the starting position in the period minus the duration of any media in previous periods still to be played.

bufferedDurationUs: Long

The duration of media currently buffered from the current playback position, in microseconds. Note that the next load position can be calculated as (playbackPositionUs + bufferedDurationUs).

availableDurationUs: Long

The duration of media available for buffering from the current playback position, in microseconds, or TIME_UNSET if media can be buffered to the end of the current period. Note that if not set to TIME_UNSET, the position up to which media is available for buffering can be calculated as (playbackPositionUs + availableDurationUs).

queue: (Mutable)List<MediaChunk!>!

The queue of already buffered MediaChunks. Must not be modified.

mediaChunkIterators: Array<MediaChunkIterator!>!

An array of MediaChunkIterators providing information about the sequence of upcoming media chunks for each track in the selection. All iterators start from the media chunk which will be loaded next if the respective track is selected. Note that this information may not be available for all tracks, and so some iterators may be empty.