BaseTrackSelection

Artifact: androidx.media3:media3-exoplayer

Kotlin |Java

@UnstableApi
abstract class BaseTrackSelection : ExoTrackSelection

Known direct subclasses

AdaptiveTrackSelection, FakeTrackSelection, FixedTrackSelection, RandomTrackSelection

`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.
`FakeTrackSelection`	A fake `ExoTrackSelection` that only returns 1 fixed track, and allows querying the number of calls to its methods.
`FixedTrackSelection`	A `TrackSelection` consisting of a single track.
`RandomTrackSelection`	An `ExoTrackSelection` whose selected track is updated randomly.

An abstract base class suitable for most ExoTrackSelection implementations.

Summary

Public constructors
`BaseTrackSelection(group: TrackGroup!, tracks: IntArray!)`
`BaseTrackSelection( group: TrackGroup!, tracks: IntArray!, @TrackSelection.Type type: Int )`

Public functions
`Unit`	`disable()` Disables this track selection.
`Unit`	`enable()` Enables the track selection.
`Boolean`	`equals(obj: Any?)`
`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.
`Format!`	`getFormat(index: Int)` Returns the format of the track at a given index in the selection.
`Int`	`getIndexInTrackGroup(index: Int)` Returns the index in the track group of the track at a given index in the selection.
`Format!`	`getSelectedFormat()` Returns the `Format` of the individual selected track.
`Int`	`getSelectedIndexInTrackGroup()` Returns the index in the track group of the individual selected track.
`TrackGroup!`	`getTrackGroup()` Returns the `TrackGroup` to which the selected tracks belong.
`Int`	`hashCode()`
`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.
`Boolean`	`isTrackExcluded(index: Int, nowMs: Long)` Returns whether the track at the specified index in the selection is excluded.
`Int`	`length()` Returns the number of tracks in the selection.
`Unit`	`@CallSuper onPlayWhenReadyChanged(playWhenReady: Boolean)` Called to notify when the playback is paused or resumed.
`Unit`	`onPlaybackSpeed(playbackSpeed: Float)` Called to notify the selection of the current playback speed.

Public properties
`Int`	`@TrackSelection.Type type` The type of the selection.

Protected properties
`TrackGroup!`	`group` The selected `TrackGroup`.
`Int`	`length` The number of selected tracks within the `TrackGroup`.
`Boolean`	`playWhenReady` The current value of whether playback will proceed when ready.
`IntArray<Int>!`	`tracks` The indices of the selected tracks in `group`, in order of decreasing bandwidth.

Inherited Constants

From androidx.media3.exoplayer.trackselection.TrackSelection

`const Int`	`TYPE_CUSTOM_BASE = 10000` The first value that can be used for application specific track selection types.
`const Int`	`TYPE_UNSET = 0` An unspecified track selection type.

Inherited functions

From androidx.media3.exoplayer.trackselection.ExoTrackSelection

`Long`	`getLatestBitrateEstimate()` Returns the most recent bitrate estimate utilised for track selection.
`abstract Int`	`getSelectedIndex()` Returns the index of the selected track.
`abstract Any?`	`getSelectionData()` Returns optional data associated with the current track selection.
`abstract Int`	`@C.SelectionReason getSelectionReason()` Returns the reason for the current track selection.
`Unit`	`onDiscontinuity()` Called to notify the selection of a position discontinuity.
`Unit`	`onRebuffer()` 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.
`abstract 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 `MediaChunk`s.

Public constructors

BaseTrackSelection

BaseTrackSelection(group: TrackGroup!, tracks: IntArray!)

Parameters
`group: TrackGroup!`	The `TrackGroup`. Must not be null.
`tracks: IntArray!`	The indices of the selected tracks within the `TrackGroup`. Must not be null or empty. May be in any order.

BaseTrackSelection

BaseTrackSelection(
    group: TrackGroup!,
    tracks: IntArray!,
    @TrackSelection.Type type: Int
)

Parameters
`group: TrackGroup!`	The `TrackGroup`. Must not be null.
`tracks: IntArray!`	The indices of the selected tracks within the `TrackGroup`. Must not be null or empty. May be in any order.
`@TrackSelection.Type type: Int`	The type that will be returned from `getType`.

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.

equals

fun equals(obj: Any?): Boolean

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.

getFormat

fun getFormat(index: Int): Format!

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

Parameters
`index: Int`	The index in the selection.

Returns
`Format!`	The format of the selected track.

getIndexInTrackGroup

fun getIndexInTrackGroup(index: Int): Int

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

Parameters
`index: Int`	The index in the selection.

Returns
`Int`	The index of the selected track.

getSelectedFormat

fun getSelectedFormat(): Format!

Returns the Format of the individual selected track.

getSelectedIndexInTrackGroup

fun getSelectedIndexInTrackGroup(): Int

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

getTrackGroup

fun getTrackGroup(): TrackGroup!

Returns the TrackGroup to which the selected tracks belong.

hashCode

fun hashCode(): Int

indexOf

fun indexOf(format: Format!): Int

Returns the index in the selection of the track with the specified format. The format is located by identity so, for example, selection.indexOf(selection.getFormat(index)) == index even if multiple selected tracks have formats that contain the same values.

Parameters
`format: Format!`	The format.

Returns
`Int`	The index in the selection, or `INDEX_UNSET` if the track with the specified format is not part of the selection.

indexOf

fun indexOf(indexInTrackGroup: Int): Int

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

Parameters
`indexInTrackGroup: Int`	The index in the track group.

Returns
`Int`	The index in the selection, or `INDEX_UNSET` if the track with the specified index is not part of the 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`.

length

fun length(): Int

Returns the number of tracks in the selection.

onPlayWhenReadyChanged

@CallSuper
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.

Public properties

type

@TrackSelection.Type
val type: Int

The type of the selection.

Protected properties

group

protected val group: TrackGroup!

The selected TrackGroup.

length

protected val length: Int

The number of selected tracks within the TrackGroup. Always greater than zero.

playWhenReady

protected val playWhenReady: Boolean

The current value of whether playback will proceed when ready.

tracks

protected val tracks: IntArray<Int>!

The indices of the selected tracks in group, in order of decreasing bandwidth.