Class: TimeEngine

TimeEngine

Base class for time engines

A time engine generates more or less regular events and/or plays back a media stream. It implements one or multiple interfaces to be driven by a master (i.e. a Scheduler, a Transport or a PlayControl) in synchronization with other engines. The provided interfaces are scheduled, transported, and play-controlled.

The scheduled interface

The scheduled interface allows for synchronizing an engine to a monotonous time as it is provided by the Scheduler master.

advanceTime(time :Number) -> {Number}

The advanceTime method has to be implemented by an TimeEngine as part of the scheduled interface. The method is called by the master (e.g. the scheduler). It generates an event and to returns the time of the next event (i.e. the next call of advanceTime). The returned time has to be greater than the time received as argument of the method. In case that a TimeEngine has to generate multiple events at the same time, the engine has to implement its own loop while(event.time <= time) and return the time of the next event (if any).

resetTime(time=undefined :Number)

The resetTime method is provided by the TimeEngine base class. An engine may call this method to reset its next event time (e.g. when a parameter is changed that influences the engine's temporal behavior). When no argument is given, the time is reset to the current master time. When calling the method with Infinity the engine is suspended without being removed from the master.

The transported interface

The transported interface allows for synchronizing an engine to a position (i.e. media playback time) that can run forward and backward and jump as it is provided by the Transport master.

syncPosition(time :Number, position :Number, speed :Number) -> {Number}

The syncPositon method has to be implemented by a TimeEngine as part of the transported interface. The method syncPositon is called whenever the master of a transported engine has to (re-)synchronize the engine's position. This is for example required when the master (re-)starts playback, jumps to an arbitrary position, and when reversing playback direction. The method returns the next position of the engine in the given playback direction (i.e. speed < 0 or speed > 0).

advancePosition(time :Number, position :Number, speed :Number) -> {Number}

The advancePosition method has to be implemented by a TimeEngine as part of the transported interface. The master calls the advancePositon method when the engine's event position is reached. The method generates an event and returns the next position in the given playback direction (i.e. speed < 0 or speed > 0). The returned position has to be greater (i.e. when speed > 0) or less (i.e. when speed < 0) than the position received as argument of the method.

resetPosition(position=undefined :Number)

The resetPosition method is provided by the TimeEngine base class. An engine may call this method to reset its next event position. When no argument is given, the time is reset to the current master time. When calling the method with Infinity the engine is suspended without being removed from the master.

The speed-controlled interface

The "speed-controlled" interface allows for syncronizing an engine that is neither driven through the scheduled nor the transported interface. The interface allows in particular to synchronize engines that assure their own scheduling (i.e. audio player or an oscillator) to the event-based scheduled and transported engines.

syncSpeed(time :Number, position :Number, speed :Number, seek=false :Boolean)

The syncSpeed method has to be implemented by a TimeEngine as part of the speed-controlled interface. The method is called by the master whenever the playback speed changes or the position jumps arbitarily (i.e. on a seek).

Example that shows a TimeEngine running in a Scheduler that counts up at a given frequency: https://rawgit.com/wavesjs/waves-audio/master/examples/time-engine.html

Constructor

new TimeEngine()

Source:
Example
import * as audio from 'waves-audio';

class MyEngine extends audio.TimeEngine {
  constructor() {
    super();
    // ...
  }
}

Members

(static) master :Mixed

The engine's master.

Type:
  • Mixed
Source:

(readonly) audioTime :Number

The time engine's current (master) audio time.

Type:
  • Number
Source:

(readonly) currentPosition :Number

The time engine's current (master) position.

Type:
  • Number
Source:

(readonly) currentTime :Number

The time engine's current (master) time.

Type:
  • Number
Source:

Methods

(static) implementsScheduled()

Scheduled interface

  • advanceTime(time), called to generate next event at given time, returns next time
Source:

(static) implementsSpeedControlled()

Speed-controlled interface

  • syncSpeed(time, position, speed, ), called to
Source:

(static) implementsTransported()

Transported interface

  • syncPosition(time, position, speed), called to reposition TimeEngine, returns next position
  • advancePosition(time, position, speed), called to generate next event at given time and position, returns next position
Source: