# ExoTrackSelection

Artifact: [androidx.media3:media3-exoplayer](https://developer.android.com/jetpack/androidx/releases/media3) [View Source](https://cs.android.com/search?q=file:androidx/media3/exoplayer/trackselection/ExoTrackSelection.java+class:androidx.media3.exoplayer.trackselection.ExoTrackSelection)

*** ** * ** ***


```
@UnstableApi
public interface ExoTrackSelection extends TrackSelection
```

<br />

Known direct subclasses [BaseTrackSelection](https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/BaseTrackSelection), [ForwardingTrackSelection](https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ForwardingTrackSelection)

|---|---|
| `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/BaseTrackSelection` | An abstract base class suitable for most `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection` implementations. |
| `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ForwardingTrackSelection` | An `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection` forwarding all calls to a wrapped instance. |

Known indirect subclasses [AdaptiveTrackSelection](https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/AdaptiveTrackSelection), [FakeTrackSelection](https://developer.android.com/reference/androidx/media3/test/utils/FakeTrackSelection), [FixedTrackSelection](https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/FixedTrackSelection), [RandomTrackSelection](https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/RandomTrackSelection)

|---|---|
| `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/AdaptiveTrackSelection` | A bandwidth based adaptive `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection`, whose selected track is updated to be the highest priority track given the current network conditions and the state of the buffer. |
| `https://developer.android.com/reference/androidx/media3/test/utils/FakeTrackSelection` | A fake `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection` that supports selecting a subset of tracks within a `https://developer.android.com/reference/androidx/media3/common/TrackGroup`, returns 1 fixed track, and tracks the number of calls to its methods. |
| `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/FixedTrackSelection` | A `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection` consisting of a single track. |
| `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/RandomTrackSelection` | An `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection` whose selected track is updated randomly. |

*** ** * ** ***

A `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection` that can change the individually selected track as a result of calling `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#updateSelectedTrack(long,long,long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>,androidx.media3.exoplayer.source.chunk.MediaChunkIterator[])` or `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#evaluateQueueSize(long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>)`. This only happens between calls to `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#enable()` and `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#disable()`.

## Summary

| ### Nested types |
|---|
| `public final class https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection.Definition` Contains of a subset of selected tracks belonging to a `https://developer.android.com/reference/androidx/media3/common/TrackGroup`. |
| `public interface https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection.Factory` Factory for `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection` instances. |

| ### Public methods |
|---|---|
| `default void` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#clearTrackExclusions()()` Clears the existing track exclusions. |
| `abstract void` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#disable()()` Disables this track selection. |
| `abstract void` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#enable()()` Enables the track selection. |
| `abstract int` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#evaluateQueueSize(long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>)(long playbackPositionUs, https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk> queue)` Returns the number of chunks that should be retained in the queue. |
| `abstract boolean` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#excludeTrack(int,long)(int index, long exclusionDurationMs)` Attempts to exclude the track at the specified index in the selection, making it ineligible for selection by calls to `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#updateSelectedTrack(long,long,long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>,androidx.media3.exoplayer.source.chunk.MediaChunkIterator[])` for the specified period of time. |
| `default long` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#getLatestBitrateEstimate()()` Returns the most recent bitrate estimate utilised for track selection. |
| `abstract https://developer.android.com/reference/androidx/media3/common/Format` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#getSelectedFormat()()` Returns the `https://developer.android.com/reference/androidx/media3/common/Format` of the individual selected track. |
| `abstract int` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#getSelectedIndex()()` Returns the index of the selected track. |
| `abstract int` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#getSelectedIndexInTrackGroup()()` Returns the index in the track group of the individual selected track. |
| `abstract @https://developer.android.com/reference/androidx/annotation/Nullable https://developer.android.com/reference/java/lang/Object.html` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#getSelectionData()()` Returns optional data associated with the current track selection. |
| `abstract int` | `@https://developer.android.com/reference/androidx/media3/common/C.SelectionReason https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#getSelectionReason()()` Returns the reason for the current track selection. |
| `abstract boolean` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#isTrackExcluded(int,long)(int index, long nowMs)` Returns whether the track at the specified index in the selection is excluded. |
| `default void` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#onDiscontinuity()()` Called to notify the selection of a position discontinuity. |
| `default void` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#onPlayWhenReadyChanged(boolean)(boolean playWhenReady)` Called to notify when the playback is paused or resumed. |
| `abstract void` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#onPlaybackSpeed(float)(float playbackSpeed)` Called to notify the selection of the current playback speed. |
| `default void` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#onRebuffer()()` Called to notify when a rebuffer occurred. |
| `default boolean` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#shouldCancelChunkLoad(long,androidx.media3.exoplayer.source.chunk.Chunk,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>)( long playbackPositionUs, https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/Chunk loadingChunk, https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk> queue )` Returns whether an ongoing load of a chunk should be canceled. |
| `abstract void` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#updateSelectedTrack(long,long,long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>,androidx.media3.exoplayer.source.chunk.MediaChunkIterator[])( long playbackPositionUs, long bufferedDurationUs, long availableDurationUs, https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk> queue, MediaChunkIterator[] mediaChunkIterators )` Updates the selected track for sources that load media in discrete `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk`s. |

| ### Inherited Constants |
|---|
| From [androidx.media3.exoplayer.trackselection.TrackSelection](https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection) |---|---| | `default static final int` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection#TYPE_CUSTOM_BASE() = 10000` The first value that can be used for application specific track selection types. | | `default static final int` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection#TYPE_UNSET() = 0` An unspecified track selection type. | |

| ### Inherited methods |
|---|
| From [androidx.media3.exoplayer.trackselection.TrackSelection](https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection) |---|---| | `abstract https://developer.android.com/reference/androidx/media3/common/Format` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection#getFormat(int)(int index)` Returns the format of the track at a given index in the selection. | | `abstract int` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection#getIndexInTrackGroup(int)(int index)` Returns the index in the track group of the track at a given index in the selection. | | `abstract https://developer.android.com/reference/androidx/media3/common/TrackGroup` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection#getTrackGroup()()` Returns the `https://developer.android.com/reference/androidx/media3/common/TrackGroup` to which the selected tracks belong. | | `abstract int` | `@https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection.Type https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection#getType()()` Returns an integer specifying the type of the selection, or `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection#TYPE_UNSET()` if not specified. | | `abstract int` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection#indexOf(androidx.media3.common.Format)(https://developer.android.com/reference/androidx/media3/common/Format format)` Returns the index in the selection of the track with the specified format. | | `abstract int` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection#indexOf(int)(int indexInTrackGroup)` Returns the index in the selection of the track with the specified index in the track group. | | `abstract int` | `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/TrackSelection#length()()` Returns the number of tracks in the selection. | |

## Public methods

### clearTrackExclusions

```
default void clearTrackExclusions()
```

Clears the existing track exclusions. The excluded tracks will be eligible for selection from the next call to `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#updateSelectedTrack(long,long,long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>,androidx.media3.exoplayer.source.chunk.MediaChunkIterator[])`.

### disable

```
abstract void disable()
```

Disables this track selection. No further dynamic changes via `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#updateSelectedTrack(long,long,long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>,androidx.media3.exoplayer.source.chunk.MediaChunkIterator[])`, `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#evaluateQueueSize(long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>)` or `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#shouldCancelChunkLoad(long,androidx.media3.exoplayer.source.chunk.Chunk,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>)` will happen after this call.

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

### enable

```
abstract void enable()
```

Enables the track selection. Dynamic changes via `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#updateSelectedTrack(long,long,long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>,androidx.media3.exoplayer.source.chunk.MediaChunkIterator[])`, `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#evaluateQueueSize(long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>)` or `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#shouldCancelChunkLoad(long,androidx.media3.exoplayer.source.chunk.Chunk,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>)` will only happen after this call.

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

### evaluateQueueSize

```
abstract 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 `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk` 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 `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#updateSelectedTrack(long,long,long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>,androidx.media3.exoplayer.source.chunk.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 `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk` 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. |
| `https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk> queue` | The queue of buffered `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk`. Must not be modified. |

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

### excludeTrack

```
abstract 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 `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#updateSelectedTrack(long,long,long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>,androidx.media3.exoplayer.source.chunk.MediaChunkIterator[])` 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 `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#updateSelectedTrack(long,long,long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>,androidx.media3.exoplayer.source.chunk.MediaChunkIterator[])`.

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. |

### getLatestBitrateEstimate

```
default long getLatestBitrateEstimate()
```

Returns the most recent bitrate estimate utilised for track selection.

The default behavior is to return `https://developer.android.com/reference/androidx/media3/common/C#RATE_UNSET_INT()`, indicating that the bitrate estimate was not computed for the track selection decision.

### getSelectedFormat

```
abstract Format getSelectedFormat()
```

Returns the `https://developer.android.com/reference/androidx/media3/common/Format` of the individual selected track.

### getSelectedIndex

```
abstract int getSelectedIndex()
```

Returns the index of the selected track.

### getSelectedIndexInTrackGroup

```
abstract int getSelectedIndexInTrackGroup()
```

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

### getSelectionData

```
abstract @Nullable Object getSelectionData()
```

Returns optional data associated with the current track selection.

### getSelectionReason

```
@C.SelectionReason
abstract int getSelectionReason()
```

Returns the reason for the current track selection.

### isTrackExcluded

```
abstract 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 `https://developer.android.com/reference/android/os/SystemClock.html#elapsedRealtime()`. |

### onDiscontinuity

```
default void onDiscontinuity()
```

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

```
default void onPlayWhenReadyChanged(boolean playWhenReady)
```

Called to notify when the playback is paused or resumed.

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

### onPlaybackSpeed

```
abstract 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. |

### onRebuffer

```
default void onRebuffer()
```

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

```
default boolean shouldCancelChunkLoad(
    long playbackPositionUs,
    Chunk loadingChunk,
    List<MediaChunk> queue
)
```

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

May be called by sources that load media in discrete `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk` and support canceling the ongoing chunk load. The ongoing chunk load is either the last `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk` in the queue or another type of `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/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 `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#evaluateQueueSize(long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>)` after the cancelation finishes to allow discarding of chunks, and `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection#updateSelectedTrack(long,long,long,java.util.List<? extends androidx.media3.exoplayer.source.chunk.MediaChunk>,androidx.media3.exoplayer.source.chunk.MediaChunkIterator[])` before loading a new chunk to allow switching to another quality.

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

| 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. |
| `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/Chunk loadingChunk` | The currently loading `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/Chunk` that will be canceled if this method returns `true`. |
| `https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk> queue` | The queue of buffered `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk`, including the ` loadingChunk` if it's a `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk`. Must not be modified. |

| Returns |
|---|---|
| `boolean` | Whether the ongoing load of `loadingChunk` should be canceled. |

### updateSelectedTrack

```
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 `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk`s.

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

| 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. |
| `long 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)`. |
| `long availableDurationUs` | The duration of media available for buffering from the current playback position, in microseconds, or `https://developer.android.com/reference/androidx/media3/common/C#TIME_UNSET()` if media can be buffered to the end of the current period. Note that if not set to `https://developer.android.com/reference/androidx/media3/common/C#TIME_UNSET()`, the position up to which media is available for buffering can be calculated as `(playbackPositionUs + availableDurationUs)`. |
| `https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk> queue` | The queue of already buffered `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunk`s. Must not be modified. |
| `MediaChunkIterator[] mediaChunkIterators` | An array of `https://developer.android.com/reference/androidx/media3/exoplayer/source/chunk/MediaChunkIterator`s 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. |