Defining preroll & clip durations

InTheAction module lets you capture video clips in a single click. To do this, you have to specify the Clip Duration and Preroll Duration values.


What is Clip Duration?

Based on the type and duration of the action that you want to record, you need to define the approximate Clip Duration of the video you are going to capture. For instance, the duration of a golf swing is approximately 3 to 4 seconds from the address to the finish of the swing.


What is Preroll Duration?

If you wait until you see the golfer start to swing before starting capture, you may miss the first moments of the swing. To avoid this you should set a Preroll Duration value which corresponds to the second(s) of video footage that took place before you started capture.

Preroll forces the computer to continually remember the number of seconds you specify. When you trigger capture it includes these seconds at the beginning of the new clip. Usually just a few seconds of preroll are required but the maximum amount is limited by the amount of available memory (RAM).


When should you start capture?

The moment when you trigger capture also creates a Default Synchronization point on the captured video. Synchpoints are used to easily synchronize video clips for comparison (see Synchronizing clips in InTheAction). For this reason it makes sense to trigger capture at an obvious point for comparison e.g. when the club strikes the ball as shown in the following diagram.

To define the preroll and clip durations.

The current settings for preroll and clip durations are displayed at the bottom of the InTheAction module as shown below.


To change these settings:

1.	Click the Change Capture Options link.

2.	Enter a Clip Duration and Preroll Duration suitable for the action being observed. The largest preroll duration you can set is related to the amount of available RAM memory of your computer.

If the duration is unknown you can still use InTheAction in it's Manual Capture mode. In this case, you will have to start AND stop the capture. You will not define any durations.