BaseTrackSelection

Artifact: androidx.media3:media3-exoplayer

Kotlin |Java

@UnstableApi
public abstract class BaseTrackSelection implements 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 fields
`final int`	`@TrackSelection.Type type` The type of the selection.

Protected fields
`final TrackGroup`	`group` The selected `TrackGroup`.
`final int`	`length` The number of selected tracks within the `TrackGroup`.
`boolean`	`playWhenReady` The current value of whether playback will proceed when ready.
`final int[]`	`tracks` The indices of the selected tracks in `group`, in order of decreasing bandwidth.

Public constructors
`BaseTrackSelection(TrackGroup group, int[] tracks)`
`BaseTrackSelection( TrackGroup group, int[] tracks, @TrackSelection.Type int type )`

Public methods
`void`	`disable()` Disables this track selection.
`void`	`enable()` Enables the track selection.
`boolean`	`equals(@Nullable Object obj)`
`int`	`evaluateQueueSize(long playbackPositionUs, List<MediaChunk> queue)` Returns the number of chunks that should be retained in the queue.
`boolean`	`excludeTrack(int index, long exclusionDurationMs)` 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.
`final Format`	`getFormat(int index)` Returns the format of the track at a given index in the selection.
`final int`	`getIndexInTrackGroup(int index)` Returns the index in the track group of the track at a given index in the selection.
`final Format`	`getSelectedFormat()` Returns the `Format` of the individual selected track.
`final int`	`getSelectedIndexInTrackGroup()` Returns the index in the track group of the individual selected track.
`final TrackGroup`	`getTrackGroup()` Returns the `TrackGroup` to which the selected tracks belong.
`final int`	`getType()` Returns an integer specifying the type of the selection, or `TYPE_UNSET` if not specified.
`int`	`hashCode()`
`final int`	`indexOf(Format format)` Returns the index in the selection of the track with the specified format.
`final int`	`indexOf(int indexInTrackGroup)` Returns the index in the selection of the track with the specified index in the track group.
`boolean`	`isTrackExcluded(int index, long nowMs)` Returns whether the track at the specified index in the selection is excluded.
`final int`	`length()` Returns the number of tracks in the selection.
`void`	`@CallSuper onPlayWhenReadyChanged(boolean playWhenReady)` Called to notify when the playback is paused or resumed.
`void`	`onPlaybackSpeed(float playbackSpeed)` Called to notify the selection of the current playback speed.

Protected methods
`final boolean`	`getPlayWhenReady()` Returns whether the playback using this track selection will proceed when ready.

Inherited Constants

From androidx.media3.exoplayer.trackselection.TrackSelection

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

Inherited methods

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 @Nullable Object`	`getSelectionData()` Returns optional data associated with the current track selection.
`abstract int`	`@C.SelectionReason getSelectionReason()` Returns the reason for the current track selection.
`void`	`onDiscontinuity()` Called to notify the selection of a position discontinuity.
`void`	`onRebuffer()` Called to notify when a rebuffer occurred.
`boolean`	`shouldCancelChunkLoad( long playbackPositionUs, Chunk loadingChunk, List<MediaChunk> queue )` Returns whether an ongoing load of a chunk should be canceled.
`abstract void`	`updateSelectedTrack( long playbackPositionUs, long bufferedDurationUs, long availableDurationUs, List<MediaChunk> queue, MediaChunkIterator[] mediaChunkIterators )` Updates the selected track for sources that load media in discrete `MediaChunk`s.

Public fields

type

@TrackSelection.Type
public final int type

The type of the selection.

Protected fields

group

protected final TrackGroup group

The selected TrackGroup.

length

protected final int length

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

playWhenReady

protected boolean playWhenReady

The current value of whether playback will proceed when ready.

tracks

protected final int[] tracks

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

Public constructors

BaseTrackSelection

public BaseTrackSelection(TrackGroup group, int[] tracks)

Parameters
`TrackGroup group`	The `TrackGroup`. Must not be null.
`int[] tracks`	The indices of the selected tracks within the `TrackGroup`. Must not be null or empty. May be in any order.

BaseTrackSelection

public BaseTrackSelection(
    TrackGroup group,
    int[] tracks,
    @TrackSelection.Type int type
)

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

Public methods

disable

public void disable()

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

public void enable()

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

public boolean equals(@Nullable Object obj)

evaluateQueueSize

public int evaluateQueueSize(long playbackPositionUs, List<MediaChunk> queue)

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
`long playbackPositionUs`	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.
`List<MediaChunk> queue`	The queue of buffered `MediaChunks`. Must not be modified.

Returns
`int`	The number of chunks to retain in the queue.

excludeTrack

public boolean excludeTrack(int index, long exclusionDurationMs)

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
`int index`	The index of the track in the selection.
`long exclusionDurationMs`	The duration of time for which the track should be excluded, in milliseconds.

Returns
`boolean`	Whether exclusion was successful.

getFormat

public final Format getFormat(int index)

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

Parameters
`int index`	The index in the selection.

Returns
`Format`	The format of the selected track.

getIndexInTrackGroup

public final int getIndexInTrackGroup(int index)

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

Parameters
`int index`	The index in the selection.

Returns
`int`	The index of the selected track.

getSelectedFormat

public final Format getSelectedFormat()

Returns the Format of the individual selected track.

getSelectedIndexInTrackGroup

public final int getSelectedIndexInTrackGroup()

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

getTrackGroup

public final TrackGroup getTrackGroup()

Returns the TrackGroup to which the selected tracks belong.

getType

public final int getType()

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

Track selection types are specific to individual applications, but should be defined starting from TYPE_CUSTOM_BASE to ensure they don't conflict with any types that may be added to the library in the future.

hashCode

public int hashCode()

indexOf

public final int indexOf(Format format)

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

public final int indexOf(int indexInTrackGroup)

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

Parameters
`int indexInTrackGroup`	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

public boolean isTrackExcluded(int index, long nowMs)

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

Parameters
`int index`	The index of the track in the selection.
`long nowMs`	The current time in the timebase of `elapsedRealtime`.

length

public final int length()

Returns the number of tracks in the selection.

onPlayWhenReadyChanged

@CallSuper
public void onPlayWhenReadyChanged(boolean playWhenReady)

Called to notify when the playback is paused or resumed.

Parameters
`boolean playWhenReady`	Whether playback will proceed when ready.

onPlaybackSpeed

public void onPlaybackSpeed(float playbackSpeed)

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

Parameters
`float playbackSpeed`	The factor by which playback is sped up.

Protected methods

getPlayWhenReady

protected final boolean getPlayWhenReady()

Returns whether the playback using this track selection will proceed when ready.