DefaultLivePlaybackSpeedControl

@UnstableApi
public final class DefaultLivePlaybackSpeedControl implements LivePlaybackSpeedControl

A LivePlaybackSpeedControl that adjusts the playback speed using a proportional controller.

The control mechanism calculates the adjusted speed as 1.0 + proportionalControlFactor x (currentLiveOffsetSec - targetLiveOffsetSec). Unit speed (1.0f) is used, if the currentLiveOffsetSec is closer to targetLiveOffsetSec than the value set with setMaxLiveOffsetErrorMsForUnitSpeed.

The resulting speed is clamped to a minimum and maximum speed defined by the media, the fallback values set with setFallbackMinPlaybackSpeed and setFallbackMaxPlaybackSpeed or the minimum and maximum fallback default values.

When the player rebuffers, the target live offset is increased to adjust to the reduced network capabilities. The live playback speed control also keeps track of the minimum possible live offset to decrease the target live offset again if conditions improve. The minimum possible live offset is derived from the current offset and the duration of buffered media.

Summary

Nested types

Builder for a DefaultLivePlaybackSpeedControl.

Constants
static final float

The default maximum factor by which playback can be sped up that should be used if no maximum playback speed is defined by the media.
static final float

The default minimum factor by which playback can be sped up that should be used if no minimum playback speed is defined by the media.
static final long

The default maximum difference between the current live offset and the target live offset, in milliseconds, for which unit speed (1.0f) is used.
static final float

The default smoothing factor when smoothing the minimum possible live offset that can be achieved during playback.
static final long

The default minimum interval between playback speed changes, in milliseconds.
static final float

The default proportional control factor used to adjust the playback speed.
static final long

The default increment applied to the target live offset each time the player is rebuffering, in milliseconds

Public methods
float
getAdjustedPlaybackSpeed(long liveOffsetUs, long bufferedDurationUs)

Returns the adjusted playback speed in order get closer towards the target live offset.
long

Returns the current target live offset, in microseconds, or TIME_UNSET if no target live offset is defined for the current media.
void

Notifies the live playback speed control that a rebuffer occurred.
void

Sets the live configuration defined by the media.
void
setTargetLiveOffsetOverrideUs(long liveOffsetUs)

Sets the target live offset in microseconds that overrides the live offset configured by the media.

Constants

DEFAULT_FALLBACK_MAX_PLAYBACK_SPEED

public static final float DEFAULT_FALLBACK_MAX_PLAYBACK_SPEED = 1.03f

The default maximum factor by which playback can be sped up that should be used if no maximum playback speed is defined by the media.

DEFAULT_FALLBACK_MIN_PLAYBACK_SPEED

public static final float DEFAULT_FALLBACK_MIN_PLAYBACK_SPEED = 0.97f

The default minimum factor by which playback can be sped up that should be used if no minimum playback speed is defined by the media.

DEFAULT_MAX_LIVE_OFFSET_ERROR_MS_FOR_UNIT_SPEED

public static final long DEFAULT_MAX_LIVE_OFFSET_ERROR_MS_FOR_UNIT_SPEED = 20

The default maximum difference between the current live offset and the target live offset, in milliseconds, for which unit speed (1.0f) is used.

DEFAULT_MIN_POSSIBLE_LIVE_OFFSET_SMOOTHING_FACTOR

public static final float DEFAULT_MIN_POSSIBLE_LIVE_OFFSET_SMOOTHING_FACTOR = 0.999f

The default smoothing factor when smoothing the minimum possible live offset that can be achieved during playback.

DEFAULT_MIN_UPDATE_INTERVAL_MS

public static final long DEFAULT_MIN_UPDATE_INTERVAL_MS = 1000

The default minimum interval between playback speed changes, in milliseconds.

DEFAULT_PROPORTIONAL_CONTROL_FACTOR

public static final float DEFAULT_PROPORTIONAL_CONTROL_FACTOR = 0.1f

The default proportional control factor used to adjust the playback speed.

DEFAULT_TARGET_LIVE_OFFSET_INCREMENT_ON_REBUFFER_MS

public static final long DEFAULT_TARGET_LIVE_OFFSET_INCREMENT_ON_REBUFFER_MS = 500

The default increment applied to the target live offset each time the player is rebuffering, in milliseconds

Public methods

getAdjustedPlaybackSpeed

public float getAdjustedPlaybackSpeed(long liveOffsetUs, long bufferedDurationUs)

Returns the adjusted playback speed in order get closer towards the target live offset.

Parameters
long liveOffsetUs

The current live offset, in microseconds.
long bufferedDurationUs

The duration of media that's currently buffered, in microseconds.
Returns
float

The adjusted factor by which playback should be sped up.

getTargetLiveOffsetUs

public long getTargetLiveOffsetUs()

Returns the current target live offset, in microseconds, or TIME_UNSET if no target live offset is defined for the current media.

notifyRebuffer

public void notifyRebuffer()

Notifies the live playback speed control that 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.

setLiveConfiguration

public void setLiveConfiguration(MediaItem.LiveConfiguration liveConfiguration)

Sets the live configuration defined by the media.

Parameters
MediaItem.LiveConfiguration liveConfiguration

The LiveConfiguration as defined by the media.

setTargetLiveOffsetOverrideUs

public void setTargetLiveOffsetOverrideUs(long liveOffsetUs)

Sets the target live offset in microseconds that overrides the live offset configured by the media. Passing C.TIME_UNSET deletes a previous override.

If no target live offset is configured by setLiveConfiguration, this override has no effect.