AdaptiveTrackSelection (ExoPlayer library)

java.lang.Object
- com.google.android.exoplayer2.trackselection.BaseTrackSelection
- - com.google.android.exoplayer2.trackselection.AdaptiveTrackSelection

All Implemented Interfaces:

ExoTrackSelection, TrackSelection
```
public class AdaptiveTrackSelection
extends BaseTrackSelection
```
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.

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description
`protected static class`	`AdaptiveTrackSelection.AdaptationCheckpoint`	Checkpoint to determine allocated bandwidth.
`static class`	`AdaptiveTrackSelection.Factory`	Factory for `AdaptiveTrackSelection` instances.

Nested classes/interfaces inherited from interface com.google.android.exoplayer2.trackselection.ExoTrackSelection
ExoTrackSelection.Definition

Field Summary

Fields
Modifier and Type	Field	Description
`static float`	`DEFAULT_BANDWIDTH_FRACTION`
`static float`	`DEFAULT_BUFFERED_FRACTION_TO_LIVE_EDGE_FOR_QUALITY_INCREASE`
`static int`	`DEFAULT_MAX_DURATION_FOR_QUALITY_DECREASE_MS`
`static int`	`DEFAULT_MIN_DURATION_FOR_QUALITY_INCREASE_MS`
`static int`	`DEFAULT_MIN_DURATION_TO_RETAIN_AFTER_DISCARD_MS`

Fields inherited from class com.google.android.exoplayer2.trackselection.BaseTrackSelection
group, length, tracks

Constructor Summary

Constructors
Modifier	Constructor	Description
	`AdaptiveTrackSelection(TrackGroup group, int[] tracks, BandwidthMeter bandwidthMeter)`
`protected`	`AdaptiveTrackSelection(TrackGroup group, int[] tracks, BandwidthMeter bandwidthMeter, long minDurationForQualityIncreaseMs, long maxDurationForQualityDecreaseMs, long minDurationToRetainAfterDiscardMs, float bandwidthFraction, float bufferedFractionToLiveEdgeForQualityIncrease, List<AdaptiveTrackSelection.AdaptationCheckpoint> adaptationCheckpoints, Clock clock)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected boolean`	`canSelectFormat(Format format, int trackBitrate, float playbackSpeed, long effectiveBitrate)`	Called when updating the selected track to determine whether a candidate track can be selected.
`void`	`disable()`	Disables this track selection.
`void`	`enable()`	Enables the track selection.
`int`	`evaluateQueueSize(long playbackPositionUs, List<? extends MediaChunk> queue)`	Returns the number of chunks that should be retained in the queue.
`protected long`	`getMinDurationToRetainAfterDiscardUs()`	Called from `evaluateQueueSize(long, List)` to determine the minimum duration of buffer to retain after discarding chunks.
`int`	`getSelectedIndex()`	Returns the index of the selected track.
`Object`	`getSelectionData()`	Returns optional data associated with the current track selection.
`int`	`getSelectionReason()`	Returns the reason for the current track selection.
`void`	`onPlaybackSpeed(float playbackSpeed)`	Called to notify the selection of the current playback speed.
`protected boolean`	`shouldEvaluateQueueSize(long nowMs, List<? extends MediaChunk> queue)`	Called from `evaluateQueueSize(long, List)` to determine whether an evaluation should be performed.
`void`	`updateSelectedTrack(long playbackPositionUs, long bufferedDurationUs, long availableDurationUs, List<? extends MediaChunk> queue, MediaChunkIterator[] mediaChunkIterators)`	Updates the selected track for sources that load media in discrete `MediaChunk`s.

Methods inherited from class com.google.android.exoplayer2.trackselection.BaseTrackSelection
blacklist, equals, getFormat, getIndexInTrackGroup, getSelectedFormat, getSelectedIndexInTrackGroup, getTrackGroup, hashCode, indexOf, indexOf, isBlacklisted, length

Methods inherited from interface com.google.android.exoplayer2.trackselection.ExoTrackSelection
onDiscontinuity, onPlayWhenReadyChanged, onRebuffer, shouldCancelChunkLoad

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - DEFAULT_MIN_DURATION_FOR_QUALITY_INCREASE_MS
```
public static final int DEFAULT_MIN_DURATION_FOR_QUALITY_INCREASE_MS
```
    See Also:
    
    Constant Field Values
  - DEFAULT_MAX_DURATION_FOR_QUALITY_DECREASE_MS
```
public static final int DEFAULT_MAX_DURATION_FOR_QUALITY_DECREASE_MS
```
    See Also:
    
    Constant Field Values
  - DEFAULT_MIN_DURATION_TO_RETAIN_AFTER_DISCARD_MS
```
public static final int DEFAULT_MIN_DURATION_TO_RETAIN_AFTER_DISCARD_MS
```
    See Also:
    
    Constant Field Values
  - DEFAULT_BANDWIDTH_FRACTION
```
public static final float DEFAULT_BANDWIDTH_FRACTION
```
    See Also:
    
    Constant Field Values
  - DEFAULT_BUFFERED_FRACTION_TO_LIVE_EDGE_FOR_QUALITY_INCREASE
```
public static final float DEFAULT_BUFFERED_FRACTION_TO_LIVE_EDGE_FOR_QUALITY_INCREASE
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - AdaptiveTrackSelection
```
public AdaptiveTrackSelection(TrackGroup group,
                              int[] tracks,
                              BandwidthMeter bandwidthMeter)
```
    Parameters:
    
    group - The TrackGroup.
    
    tracks - The indices of the selected tracks within the TrackGroup. Must not be empty. May be in any order.
    
    bandwidthMeter - Provides an estimate of the currently available bandwidth.
  - AdaptiveTrackSelection
```
protected AdaptiveTrackSelection(TrackGroup group,
                                 int[] tracks,
                                 BandwidthMeter bandwidthMeter,
                                 long minDurationForQualityIncreaseMs,
                                 long maxDurationForQualityDecreaseMs,
                                 long minDurationToRetainAfterDiscardMs,
                                 float bandwidthFraction,
                                 float bufferedFractionToLiveEdgeForQualityIncrease,
                                 List<AdaptiveTrackSelection.AdaptationCheckpoint> adaptationCheckpoints,
                                 Clock clock)
```
    Parameters:
    
    group - The TrackGroup.
    
    tracks - The indices of the selected tracks within the TrackGroup. Must not be empty. May be in any order.
    
    bandwidthMeter - Provides an estimate of the currently available bandwidth.
    
    minDurationForQualityIncreaseMs - The minimum duration of buffered data required for the selected track to switch to one of higher quality.
    
    maxDurationForQualityDecreaseMs - The maximum duration of buffered data required for the selected track to switch to one of lower quality.
    
    minDurationToRetainAfterDiscardMs - When switching to a track of significantly higher quality, the selection may indicate that media already buffered at the lower quality can be discarded to speed up the switch. This is the minimum duration of media that must be retained at the lower quality.
    
    bandwidthFraction - The fraction of the available bandwidth that the selection should consider available for use. Setting to a value less than 1 is recommended to account for inaccuracies in the bandwidth estimator.
    
    bufferedFractionToLiveEdgeForQualityIncrease - For live streaming, the fraction of the duration from current playback position to the live edge that has to be buffered before the selected track can be switched to one of higher quality. This parameter is only applied when the playback position is closer to the live edge than minDurationForQualityIncreaseMs, which would otherwise prevent switching to a higher quality from happening.
    
    adaptationCheckpoints - The checkpoints that can be used to calculate available bandwidth for this selection.
    
    clock - The Clock.
- Method Detail
  - enable
```
@CallSuper
public void enable()
```
    Description copied from interface: ExoTrackSelection
    
    Enables the track selection. Dynamic changes via ExoTrackSelection.updateSelectedTrack(long, long, long, List, MediaChunkIterator[]), ExoTrackSelection.evaluateQueueSize(long, List) or ExoTrackSelection.shouldCancelChunkLoad(long, Chunk, List) will only happen after this call.
    This method may not be called when the track selection is already enabled.
    
    Specified by:
    
    enable in interface ExoTrackSelection
    
    Overrides:
    
    enable in class BaseTrackSelection
  - disable
```
@CallSuper
public void disable()
```
    Description copied from interface: ExoTrackSelection
    
    Disables this track selection. No further dynamic changes via ExoTrackSelection.updateSelectedTrack(long, long, long, List, MediaChunkIterator[]), ExoTrackSelection.evaluateQueueSize(long, List) or ExoTrackSelection.shouldCancelChunkLoad(long, Chunk, List) will happen after this call.
    This method may only be called when the track selection is already enabled.
    
    Specified by:
    
    disable in interface ExoTrackSelection
    
    Overrides:
    
    disable in class BaseTrackSelection
  - onPlaybackSpeed
```
public void onPlaybackSpeed(float playbackSpeed)
```
    Description copied from interface: ExoTrackSelection
    
    Called to notify the selection of the current playback speed. The playback speed may affect adaptive track selection.
    
    Specified by:
    
    onPlaybackSpeed in interface ExoTrackSelection
    
    Overrides:
    
    onPlaybackSpeed in class BaseTrackSelection
    
    Parameters:
    
    playbackSpeed - The factor by which playback is sped up.
  - updateSelectedTrack
```
public void updateSelectedTrack(long playbackPositionUs,
                                long bufferedDurationUs,
                                long availableDurationUs,
                                List<? extends MediaChunk> queue,
                                MediaChunkIterator[] mediaChunkIterators)
```
    Description copied from interface: ExoTrackSelection
    
    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 - 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 - 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 - The duration of media available for buffering from the current playback position, in microseconds, or C.TIME_UNSET if media can be buffered to the end of the current period. Note that if not set to C.TIME_UNSET, the position up to which media is available for buffering can be calculated as (playbackPositionUs + availableDurationUs).
    
    queue - The queue of already buffered MediaChunks. Must not be modified.
    
    mediaChunkIterators - 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.
  - getSelectedIndex
```
public int getSelectedIndex()
```
    Description copied from interface: ExoTrackSelection
    
    Returns the index of the selected track.
  - getSelectionReason
```
public int getSelectionReason()
```
    Description copied from interface: ExoTrackSelection
    
    Returns the reason for the current track selection.
  - getSelectionData
```
@Nullable
public Object getSelectionData()
```
    Description copied from interface: ExoTrackSelection
    
    Returns optional data associated with the current track selection.
  - evaluateQueueSize
```
public int evaluateQueueSize(long playbackPositionUs,
                             List<? extends MediaChunk> queue)
```
    Description copied from interface: ExoTrackSelection
    
    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 ExoTrackSelection.updateSelectedTrack(long, long, long, List, MediaChunkIterator[]) 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.
    
    Specified by:
    
    evaluateQueueSize in interface ExoTrackSelection
    
    Overrides:
    
    evaluateQueueSize in class BaseTrackSelection
    
    Parameters:
    
    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.
    
    queue - The queue of buffered MediaChunks. Must not be modified.
    
    Returns:
    
    The number of chunks to retain in the queue.
  - canSelectFormat
```
protected boolean canSelectFormat(Format format,
                                  int trackBitrate,
                                  float playbackSpeed,
                                  long effectiveBitrate)
```
    Called when updating the selected track to determine whether a candidate track can be selected.
    
    Parameters:
    
    format - The Format of the candidate track.
    
    trackBitrate - The estimated bitrate of the track. May differ from Format.bitrate if a more accurate estimate of the current track bitrate is available.
    
    playbackSpeed - The current factor by which playback is sped up.
    
    effectiveBitrate - The bitrate available to this selection.
    
    Returns:
    
    Whether this Format can be selected.
  - shouldEvaluateQueueSize
```
protected boolean shouldEvaluateQueueSize(long nowMs,
                                          List<? extends MediaChunk> queue)
```
    Called from evaluateQueueSize(long, List) to determine whether an evaluation should be performed.
    
    Parameters:
    
    nowMs - The current value of Clock.elapsedRealtime().
    
    queue - The queue of buffered MediaChunks. Must not be modified.
    
    Returns:
    
    Whether an evaluation should be performed.
  - getMinDurationToRetainAfterDiscardUs
```
protected long getMinDurationToRetainAfterDiscardUs()
```
    Called from evaluateQueueSize(long, List) to determine the minimum duration of buffer to retain after discarding chunks.
    
    Returns:
    
    The minimum duration of buffer to retain after discarding chunks, in microseconds.

Class AdaptiveTrackSelection

Nested Class Summary

Nested classes/interfaces inherited from interface com.google.android.exoplayer2.trackselection.ExoTrackSelection

Field Summary

Fields inherited from class com.google.android.exoplayer2.trackselection.BaseTrackSelection

Constructor Summary

Method Summary

Methods inherited from class com.google.android.exoplayer2.trackselection.BaseTrackSelection

Methods inherited from interface com.google.android.exoplayer2.trackselection.ExoTrackSelection

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_MIN_DURATION_FOR_QUALITY_INCREASE_MS

DEFAULT_MAX_DURATION_FOR_QUALITY_DECREASE_MS

DEFAULT_MIN_DURATION_TO_RETAIN_AFTER_DISCARD_MS

DEFAULT_BANDWIDTH_FRACTION

DEFAULT_BUFFERED_FRACTION_TO_LIVE_EDGE_FOR_QUALITY_INCREASE

Constructor Detail

AdaptiveTrackSelection

AdaptiveTrackSelection

Method Detail

enable

disable

onPlaybackSpeed

updateSelectedTrack

getSelectedIndex

getSelectionReason

getSelectionData

evaluateQueueSize

canSelectFormat

shouldEvaluateQueueSize

getMinDurationToRetainAfterDiscardUs