# MaskingMediaPeriod

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/source/MaskingMediaPeriod.java+class:androidx.media3.exoplayer.source.MaskingMediaPeriod)

*** ** * ** ***


```
@UnstableApi
public final class MaskingMediaPeriod implements MediaPeriod, MediaPeriod.Callback
```

<br />

*** ** * ** ***

Media period that defers calling `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource#createPeriod(androidx.media3.exoplayer.source.MediaSource.MediaPeriodId,androidx.media3.exoplayer.upstream.Allocator,long)` on a given source until `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#createPeriod(androidx.media3.exoplayer.source.MediaSource.MediaPeriodId)` has been called. This is useful if you need to return a media period immediately but the media source that should create it is not yet available or prepared.

## Summary

| ### Nested types |
|---|
| `public interface https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod.PrepareListener` Listener for preparation events. |

| ### Public fields |
|---|---|
| `final https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource.MediaPeriodId` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#id()` The `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource.MediaPeriodId` used to create the masking media period. |
| `long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#preparePositionOverrideUs()` |
| `final long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#preparePositionUs()` |

| ### Public constructors |
|---|
| `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#MaskingMediaPeriod(androidx.media3.exoplayer.source.MediaSource.MediaPeriodId,androidx.media3.exoplayer.upstream.Allocator,long)( https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource.MediaPeriodId id, https://developer.android.com/reference/androidx/media3/exoplayer/upstream/Allocator allocator, long preparePositionUs )` Creates a new masking media period. |

| ### Public methods |
|---|---|
| `boolean` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#continueLoading(androidx.media3.exoplayer.LoadingInfo)(https://developer.android.com/reference/androidx/media3/exoplayer/LoadingInfo loadingInfo)` Attempts to continue loading. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#createPeriod(androidx.media3.exoplayer.source.MediaSource.MediaPeriodId)(https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource.MediaPeriodId id)` Calls `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource#createPeriod(androidx.media3.exoplayer.source.MediaSource.MediaPeriodId,androidx.media3.exoplayer.upstream.Allocator,long)` on the wrapped source then prepares it if `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#prepare(androidx.media3.exoplayer.source.MediaPeriod.Callback,long)` has been called. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#discardBuffer(long,boolean)(long positionUs, boolean toKeyframe)` Discards buffered media up to the specified position. |
| `long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#getAdjustedSeekPositionUs(long,androidx.media3.exoplayer.SeekParameters)( long positionUs, https://developer.android.com/reference/androidx/media3/exoplayer/SeekParameters seekParameters )` Returns the position to which a seek will be performed, given the specified seek position and `https://developer.android.com/reference/androidx/media3/exoplayer/SeekParameters`. |
| `long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#getBufferedPositionUs()()` Returns an estimate of the position up to which data is buffered for the enabled tracks. |
| `long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#getNextLoadPositionUs()()` Returns the next load time, or `https://developer.android.com/reference/androidx/media3/common/C#TIME_END_OF_SOURCE()` if loading has finished. |
| `long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#getPreparePositionOverrideUs()()` Returns the prepare position override set by `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#overridePreparePositionUs(long)`. |
| `long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#getPreparePositionUs()()` Returns the position at which the masking media period was prepared, in microseconds. |
| `https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/androidx/media3/common/StreamKey>` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#getStreamKeys(java.util.List<androidx.media3.exoplayer.trackselection.ExoTrackSelection>)(https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection> trackSelections)` Returns a list of `https://developer.android.com/reference/androidx/media3/common/StreamKey` which allow to filter the media in this period to load only the parts needed to play the provided `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection`. |
| `https://developer.android.com/reference/androidx/media3/exoplayer/source/TrackGroupArray` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#getTrackGroups()()` Returns the `https://developer.android.com/reference/androidx/media3/common/TrackGroup`s exposed by the period. |
| `boolean` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#isLoading()()` Returns whether the media period is currently loading. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#maybeThrowPrepareError()()` Throws an error that's preventing the period from becoming prepared. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#onContinueLoadingRequested(androidx.media3.exoplayer.source.MediaPeriod)(https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod source)` Called by the loader to indicate that it wishes for its `https://developer.android.com/reference/androidx/media3/exoplayer/source/SequenceableLoader#continueLoading(androidx.media3.exoplayer.LoadingInfo)` method to be called when it can continue to load data. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#onPrepared(androidx.media3.exoplayer.source.MediaPeriod)(https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod mediaPeriod)` Called when preparation completes. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#overridePreparePositionUs(long)(long preparePositionUs)` Overrides the default prepare position at which to prepare the media period. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#prepare(androidx.media3.exoplayer.source.MediaPeriod.Callback,long)(https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod.Callback callback, long positionUs)` Prepares this media period asynchronously. |
| `long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#readDiscontinuity()()` Attempts to read a discontinuity. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#reevaluateBuffer(long)(long positionUs)` Re-evaluates the buffer given the playback position. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#releasePeriod()()` Releases the period. |
| `long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#seekToUs(long)(long positionUs)` Attempts to seek to the specified position in microseconds. |
| `long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#selectTracks(androidx.media3.exoplayer.trackselection.ExoTrackSelection[],boolean[],androidx.media3.exoplayer.source.SampleStream[],boolean[],long)( @https://developer.android.com/reference/androidx/media3/common/util/NullableType ExoTrackSelection[] selections, boolean[] mayRetainStreamFlags, @https://developer.android.com/reference/androidx/media3/common/util/NullableType SampleStream[] streams, boolean[] streamResetFlags, long positionUs )` Performs a track selection. |
| `long` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#setEndPositionUs(long)(long endPositionUs)` Sets the end position at which the period stops loading and providing samples. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#setMediaSource(androidx.media3.exoplayer.source.MediaSource)(https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource mediaSource)` Sets the `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource` that will create the underlying media period. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#setPrepareListener(androidx.media3.exoplayer.source.MaskingMediaPeriod.PrepareListener)(https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod.PrepareListener listener)` Sets a listener for preparation events. |
| `void` | `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#setUsesStreamPrerollFlags()()` Notifies the media period that the player will use `https://developer.android.com/reference/androidx/media3/exoplayer/source/SampleStream#getFlags()` to check if streams contain initial discontinuities at the start of the period rather than using `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod#readDiscontinuity()`. |

## Public fields

### id

```
public final MediaSource.MediaPeriodId id
```

The `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource.MediaPeriodId` used to create the masking media period.

### preparePositionOverrideUs

```
public long preparePositionOverrideUs
```

### preparePositionUs

```
public final long preparePositionUs
```

## Public constructors

### MaskingMediaPeriod

```
public MaskingMediaPeriod(
    MediaSource.MediaPeriodId id,
    Allocator allocator,
    long preparePositionUs
)
```

Creates a new masking media period. The media source must be set via `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#setMediaSource(androidx.media3.exoplayer.source.MediaSource)` before preparation can start.

| Parameters |
|---|---|
| `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource.MediaPeriodId id` | The identifier used to create the masking media period. |
| `https://developer.android.com/reference/androidx/media3/exoplayer/upstream/Allocator allocator` | The allocator used to create the media period. |
| `long preparePositionUs` | The expected start position, in microseconds. |

## Public methods

### continueLoading

```
public boolean continueLoading(LoadingInfo loadingInfo)
```

Attempts to continue loading.

This method may be called both during and after the period has been prepared.

A period may call `https://developer.android.com/reference/androidx/media3/exoplayer/source/SequenceableLoader.Callback#onContinueLoadingRequested(T)` on the `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod.Callback` passed to `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod#prepare(androidx.media3.exoplayer.source.MediaPeriod.Callback,long)` to request that this method be called when the period is permitted to continue loading data. A period may do this both during and after preparation.

| Parameters |
|---|---|
| `https://developer.android.com/reference/androidx/media3/exoplayer/LoadingInfo loadingInfo` | The `https://developer.android.com/reference/androidx/media3/exoplayer/LoadingInfo` when attempting to continue loading. |

| Returns |
|---|---|
| `boolean` | True if progress was made, meaning that `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod#getNextLoadPositionUs()` will return a different value than prior to the call. False otherwise. |

### createPeriod

```
public void createPeriod(MediaSource.MediaPeriodId id)
```

Calls `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource#createPeriod(androidx.media3.exoplayer.source.MediaSource.MediaPeriodId,androidx.media3.exoplayer.upstream.Allocator,long)` on the wrapped source then prepares it if `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#prepare(androidx.media3.exoplayer.source.MediaPeriod.Callback,long)` has been called. Call `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#releasePeriod()` to release the period.

| Parameters |
|---|---|
| `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource.MediaPeriodId id` | The identifier that should be used to create the media period from the media source. |

### discardBuffer

```
public void discardBuffer(long positionUs, boolean toKeyframe)
```

Discards buffered media up to the specified position.

This method is only called after the period has been prepared.

| Parameters |
|---|---|
| `long positionUs` | The position in microseconds. |
| `boolean toKeyframe` | If true then for each track discards samples up to the keyframe before or at the specified position, rather than any sample before or at that position. |

### getAdjustedSeekPositionUs

```
public long getAdjustedSeekPositionUs(
    long positionUs,
    SeekParameters seekParameters
)
```

Returns the position to which a seek will be performed, given the specified seek position and `https://developer.android.com/reference/androidx/media3/exoplayer/SeekParameters`.

This method is only called after the period has been prepared.

| Parameters |
|---|---|
| `long positionUs` | The seek position in microseconds. |
| `https://developer.android.com/reference/androidx/media3/exoplayer/SeekParameters seekParameters` | Parameters that control how the seek is performed. Implementations may apply seek parameters on a best effort basis. |

| Returns |
|---|---|
| `long` | The actual position to which a seek will be performed, in microseconds. |

### getBufferedPositionUs

```
public long getBufferedPositionUs()
```

Returns an estimate of the position up to which data is buffered for the enabled tracks.

This method is only called when at least one track is selected.

| Returns |
|---|---|
| `long` | An estimate of the absolute position in microseconds up to which data is buffered, or `https://developer.android.com/reference/androidx/media3/common/C#TIME_END_OF_SOURCE()` if the track is fully buffered. |

### getNextLoadPositionUs

```
public long getNextLoadPositionUs()
```

Returns the next load time, or `https://developer.android.com/reference/androidx/media3/common/C#TIME_END_OF_SOURCE()` if loading has finished.

This method is only called after the period has been prepared. It may be called when no tracks are selected.

### getPreparePositionOverrideUs

```
public long getPreparePositionOverrideUs()
```

Returns the prepare position override set by `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#overridePreparePositionUs(long)`.

### getPreparePositionUs

```
public long getPreparePositionUs()
```

Returns the position at which the masking media period was prepared, in microseconds.

### getStreamKeys

```
public List<StreamKey> getStreamKeys(List<ExoTrackSelection> trackSelections)
```

Returns a list of `https://developer.android.com/reference/androidx/media3/common/StreamKey` which allow to filter the media in this period to load only the parts needed to play the provided `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection`.

This method is only called after the period has been prepared.

| Parameters |
|---|---|
| `https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection> trackSelections` | The `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection` describing the tracks for which stream keys are requested. |

| Returns |
|---|---|
| `https://developer.android.com/reference/java/util/List.html<https://developer.android.com/reference/androidx/media3/common/StreamKey>` | The corresponding `https://developer.android.com/reference/androidx/media3/common/StreamKey` for the selected tracks, or an empty list if filtering is not possible and the entire media needs to be loaded to play the selected tracks. |

### getTrackGroups

```
public TrackGroupArray getTrackGroups()
```

Returns the `https://developer.android.com/reference/androidx/media3/common/TrackGroup`s exposed by the period.

This method is only called after the period has been prepared.

| Returns |
|---|---|
| `https://developer.android.com/reference/androidx/media3/exoplayer/source/TrackGroupArray` | The `https://developer.android.com/reference/androidx/media3/common/TrackGroup`s. |

### isLoading

```
public boolean isLoading()
```

Returns whether the media period is currently loading.

### maybeThrowPrepareError

```
public void maybeThrowPrepareError()
```

Throws an error that's preventing the period from becoming prepared. Does nothing if no such error exists.

This method is only called before the period has completed preparation.

| Throws |
|---|---|
| `https://developer.android.com/reference/java/io/IOException.html` | The underlying error. |

### onContinueLoadingRequested

```
public void onContinueLoadingRequested(MediaPeriod source)
```

Called by the loader to indicate that it wishes for its `https://developer.android.com/reference/androidx/media3/exoplayer/source/SequenceableLoader#continueLoading(androidx.media3.exoplayer.LoadingInfo)` method to be called when it can continue to load data. Called on the playback thread.

### onPrepared

```
public void onPrepared(MediaPeriod mediaPeriod)
```

Called when preparation completes.

Called on the playback thread. After invoking this method, the `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod` can expect for `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod#selectTracks(androidx.media3.exoplayer.trackselection.ExoTrackSelection[],boolean[],androidx.media3.exoplayer.source.SampleStream[],boolean[],long)` to be called with the initial track selection.

| Parameters |
|---|---|
| `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod mediaPeriod` | The prepared `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod`. |

### overridePreparePositionUs

```
public void overridePreparePositionUs(long preparePositionUs)
```

Overrides the default prepare position at which to prepare the media period. This method must be called before `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#createPeriod(androidx.media3.exoplayer.source.MediaSource.MediaPeriodId)`.

| Parameters |
|---|---|
| `long preparePositionUs` | The default prepare position to use, in microseconds. |

### prepare

```
public void prepare(MediaPeriod.Callback callback, long positionUs)
```

Prepares this media period asynchronously.

`callback.onPrepared` is called when preparation completes. If preparation fails, `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod#maybeThrowPrepareError()` will throw an `https://developer.android.com/reference/java/io/IOException.html`.

If preparation succeeds and results in a source timeline change (e.g. the period duration becoming known), `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource.MediaSourceCaller#onSourceInfoRefreshed(androidx.media3.exoplayer.source.MediaSource,androidx.media3.common.Timeline)` will be called before `callback.onPrepared`.

| Parameters |
|---|---|
| `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod.Callback callback` | Callback to receive updates from this period, including being notified when preparation completes. |
| `long positionUs` | The expected starting position, in microseconds. |

### readDiscontinuity

```
public long readDiscontinuity()
```

Attempts to read a discontinuity.

A discontinuity implies that the provided `https://developer.android.com/reference/androidx/media3/exoplayer/source/SampleStream` will start from a new playback position and any output pipelines need to be reset. This happens for example if the streams provide decode-only samples before the intended playback start position that need to be dropped.

After this method has returned a value other than `https://developer.android.com/reference/androidx/media3/common/C#TIME_UNSET()`, all `https://developer.android.com/reference/androidx/media3/exoplayer/source/SampleStream` provided by the period are guaranteed to start from a key frame.

This method is only called after the period has been prepared.

| Returns |
|---|---|
| `long` | The playback position after the discontinuity, in microseconds, or `https://developer.android.com/reference/androidx/media3/common/C#TIME_UNSET()` if there is no discontinuity. |

### reevaluateBuffer

```
public void reevaluateBuffer(long positionUs)
```

Re-evaluates the buffer given the playback position.

This method is only called after the period has been prepared.

A period may choose to discard buffered media or cancel ongoing loads so that media can be re-buffered in a different quality.

| Parameters |
|---|---|
| `long positionUs` | The current playback position in microseconds. If playback of this period has not yet started, the value will be the starting position in this period minus the duration of any media in previous periods still to be played. |

### releasePeriod

```
public void releasePeriod()
```

Releases the period.

### seekToUs

```
public long seekToUs(long positionUs)
```

Attempts to seek to the specified position in microseconds.

After this method has been called, all `https://developer.android.com/reference/androidx/media3/exoplayer/source/SampleStream`s provided by the period are guaranteed to start from a key frame.

This method is only called when at least one track is selected.

| Parameters |
|---|---|
| `long positionUs` | The seek position in microseconds. |

| Returns |
|---|---|
| `long` | The actual position to which the period was seeked, in microseconds. |

### selectTracks

```
public long selectTracks(
    @NullableType ExoTrackSelection[] selections,
    boolean[] mayRetainStreamFlags,
    @NullableType SampleStream[] streams,
    boolean[] streamResetFlags,
    long positionUs
)
```

Performs a track selection.

The call receives track `selections` for each renderer, `mayRetainStreamFlags` indicating whether the existing `https://developer.android.com/reference/androidx/media3/exoplayer/source/SampleStream` can be retained for each selection, and the existing `stream`s themselves. The call will update `streams` to reflect the provided selections, clearing, setting and replacing entries as required. If an existing sample stream is retained but with the requirement that the consuming renderer be reset, then the corresponding flag in `streamResetFlags` will be set to true. This flag will also be set if a new sample stream is created.

Note that previously passed `https://developer.android.com/reference/androidx/media3/exoplayer/trackselection/ExoTrackSelection` are no longer valid, and any references to them must be updated to point to the new selections.

This method is only called after the period has been prepared.

| Parameters |
|---|---|
| `@https://developer.android.com/reference/androidx/media3/common/util/NullableType ExoTrackSelection[] selections` | The renderer track selections. |
| `boolean[] mayRetainStreamFlags` | Flags indicating whether the existing sample stream can be retained for each track selection. A `true` value indicates that the selection is equivalent to the one that was previously passed, and that the caller does not require that the sample stream be recreated. If a retained sample stream holds any references to the track selection then they must be updated to point to the new selection. |
| `@https://developer.android.com/reference/androidx/media3/common/util/NullableType SampleStream[] streams` | The existing sample streams, which will be updated to reflect the provided selections. |
| `boolean[] streamResetFlags` | Will be updated to indicate new sample streams, and sample streams that have been retained but with the requirement that the consuming renderer be reset. |
| `long positionUs` | The current playback position in microseconds. If playback of this period has not yet started, the value will be the starting position. |

| Returns |
|---|---|
| `long` | The actual position at which the tracks were enabled, in microseconds. |

### setEndPositionUs

```
public long setEndPositionUs(long endPositionUs)
```

Sets the end position at which the period stops loading and providing samples.

This method may be called at any time.

If a value other than `https://developer.android.com/reference/androidx/media3/common/C#TIME_END_OF_SOURCE()` is returned, the implementation must stop returning samples from the created `https://developer.android.com/reference/androidx/media3/exoplayer/source/SampleStream` instances beyond the specified end position and mark further reads with `https://developer.android.com/reference/androidx/media3/common/C#BUFFER_FLAG_END_OF_STREAM()`. The stream may return additional out of order samples required for decoding.

| Parameters |
|---|---|
| `long endPositionUs` | The requested end position, in microseconds, or `https://developer.android.com/reference/androidx/media3/common/C#TIME_END_OF_SOURCE()` to not set an end position. |

| Returns |
|---|---|
| `long` | Returns the actual position, in microseconds, at which the source stops loading and providing samples, or `https://developer.android.com/reference/androidx/media3/common/C#TIME_END_OF_SOURCE()` if setting the end position is not supported and all samples until then end of the source will be provided. |

### setMediaSource

```
public void setMediaSource(MediaSource mediaSource)
```

Sets the `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaSource` that will create the underlying media period.

### setPrepareListener

```
public void setPrepareListener(MaskingMediaPeriod.PrepareListener listener)
```

Sets a listener for preparation events.

| Parameters |
|---|---|
| `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod.PrepareListener listener` | An listener to be notified of media period preparation events. If a listener is set, `https://developer.android.com/reference/androidx/media3/exoplayer/source/MaskingMediaPeriod#maybeThrowPrepareError()` will not throw but will instead pass the first preparation error (if any) to the listener. |

### setUsesStreamPrerollFlags

```
public void setUsesStreamPrerollFlags()
```

Notifies the media period that the player will use `https://developer.android.com/reference/androidx/media3/exoplayer/source/SampleStream#getFlags()` to check if streams contain initial discontinuities at the start of the period rather than using `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod#readDiscontinuity()`.

If invoked then `https://developer.android.com/reference/androidx/media3/exoplayer/source/MediaPeriod#readDiscontinuity()` should only report discontinuities that occur during playback, not any initial discontinuities at the start of the period.