Flash 8 Cookbook

3.3. Setting the Frame Rate

Problem

You want to set the frame rate of a Flash document.

Solution

Set the frame rate value in the Document Properties or in the Property inspector.

Discussion

To register in the human brain, an image needs a certain amount of time—it is not instantaneous; this is referred to as persistence of vision. If an animation or video format displays images faster than the time the brain requires to process an image, the illusion of fluid motion is created. If, on the other hand, images are displayed slower than the persistence of vision, individual images are perceptible, and the animation or video looks uneven. In animation and video each image in the sequence is called a frame. Higher frame rates (more frames per second) generally result in smoother animation.

Unless you change the default settings, Flash uses 12 frames per second for new documents. However, the setting of 12 frames per second is not optimal in every situation. High-quality animation and video outlets, such as television and movies, use nearly 30 frames per second, so Flash’s default setting is obviously lower in quality than those media. However, before you set the frame rate of a Flash document to 30 or greater (Flash allows a maximum frame rate of 120 frames per second) you need to consider whether the SWF will be able to run at that frame rate.

There are two basic factors that affect the actual frame rate at which an SWF plays back—the amount of processing power required by the SWF and the amount ...