Scrubbing TimelinePlus

TimelinePlus playback behaviour:

TimelinePlus triggers values (keyframes) on it’s tracks when the play head passes over them: in normal playback this is easily seen and understood. Whether or not to trigger keyframes becomes a little more complex when commands, jumps and stopping the timeline is introduced. This will try to explain what TimelinePlus will do in these cases.

Playback at Key Frames:

TimelinePlus is an event-based keyframe timeline; meaning it only makes changes to the elements (called Pins in Hippotizer) under it’s control when the Playhead crosses the keyframe.

If there is no keyframe (or fade between keyframes) on the track at the playhead then TimelinePlus will not change the corresponding pin value. This is similar to the way that a tracking lighting console works.

*Pins in Hippotizer operate on a Last Takes Precedence (LTP) basis. If two methods try to set the same pin whichever is last will set the value. Some methods (such as DMX) continuously set the pin value so a change made through Zookeeper will quickly be overridden by DMX resulting in the pin ‘snapping back’.

A Timeline generally only sets a pin once as the playhead passes over the keyframe, the exception to this is fades between two values of float key frames: during the fade the timeline will continuously set the pin value in order to execute the fade.

Playback Between Key Frames:

When the playhead is playing between key frames the timeline normally will not set pin values. (Except for fades as described above)

There are cases however where it becomes necessary to re-evaluate pin values at the play head even if there is not a key frame. This is called scrubbing the timeline.

In TimelinePlus there are two ways to scrub:

• While the timeline is playing, use a jump command to send the playhead to a new location in the timeline. Upon landing from the jump, the timeline will re-evaluate all tracks and set pin values even if its between key frames.
• While Playing, If a timeline has been stopped with the space bar or by pressing play, manually moving the playhead will re-evaluate all tracks if the scrub setting is enabled.
  

In all other cases (such as starting a timeline from a Stop Command) the timeline will not re-evaluate track values unless it’s a key frame. This is a key design aspect of the system as it allows for seamless loops to be programmed.