TrackSelector

@UnstableApi
public abstract class TrackSelector

The component of an ExoPlayer responsible for selecting tracks to be consumed by each of the player's Renderers. The DefaultTrackSelector implementation should be suitable for most use cases.

Interactions with the player

• When the player is created it will initialize the track selector by calling init.
• When the player needs to make a track selection it will call selectTracks. This typically occurs at the start of playback, when the player starts to buffer a new period of the media being played, and when the track selector invalidates its previous selections.
• The player may perform a track selection well in advance of the selected tracks becoming active, where active is defined to mean that the renderers are actually consuming media corresponding to the selection that was made. For example when playing media containing multiple periods, the track selection for a period is made when the player starts to buffer that period. Hence if the player's buffering policy is to maintain a 30 second buffer, the selection will occur approximately 30 seconds in advance of it becoming active. In fact the selection may never become active, for example if the user seeks to some other period of the media during the 30 second gap. The player indicates to the track selector when a selection it has previously made becomes active by calling onSelectionActivated.
• When the track selector's configuration changes (for example, if it now wishes to prefer audio tracks in a particular language) or its previous selections become invalid, it can trigger invalidation by calling invalidate. This invokes onTrackSelectionsInvalidated on the InvalidationListener that was passed to init. When handling this callback, if parameters is not null, the listener must call onParametersActivated to activate the updated parameters before triggering the player to make new track selections. Note that the player will have to re-buffer if the new track selection for the currently playing period differs from the one that was invalidated.
• When the player is released, it will release the track selector by calling release.

Track selection parameters

Track selection parameters can be retrieved and modified on the application thread by calling getParameters and setParameters respectively (if supported, as indicated by isSetParametersSupported). Modifying parameters on the application thread triggers the invalidation flow described above, ensuring that the updated parameters are activated and applied on the playback thread.

Renderer configuration

Threading model

All methods must be called on the same playback thread, except for those specifically documented to be called on a separate application thread.

Summary

protected @Nullable BandwidthMeter bandwidthMeter

public TrackSelector()

public TrackSelectionParameters getParameters()

public @Nullable RendererCapabilities.Listener getRendererCapabilitiesListener()

@CallSuper
public void init(
    TrackSelector.InvalidationListener listener,
    BandwidthMeter bandwidthMeter
)

public boolean isSetParametersSupported()

public void onParametersActivated(@Nullable TrackSelectionParameters parameters)

public abstract void onSelectionActivated(@Nullable Object info)

@CallSuper
public void release()

public abstract TrackSelectorResult selectTracks(
    RendererCapabilities[] rendererCapabilities,
    TrackGroupArray trackGroups,
    MediaSource.MediaPeriodId periodId,
    Timeline timeline
)

public void setAudioAttributes(AudioAttributes audioAttributes)

public void setParameters(TrackSelectionParameters parameters)

protected final BandwidthMeter getBandwidthMeter()

protected final void invalidate(@Nullable TrackSelectionParameters parameters)

protected final void invalidateForRendererCapabilitiesChange(Renderer renderer)