Frame rate, properties, and size

It's important to be aware of the relationship between frame rate, animated properties, and file size. When you export a composition to the SWF format, the file stores all changing values for an object on every frame on which a property changes. Although this is only about 6 bytes per frame for each changing property, the total can become large, especially at higher frame rates.

For example, suppose you have an object that changes position during a 1-second long animation set to 10 frames per second (fps). The tweening would require approximately 60 bytes (6 bytes times 10 frames) when you exported the animation. If you tripled the frame rate to 30 fps for smoother animation, three times as much tweening information would be created--about 180 bytes--when you exported the animation. Animating a second property, such as object opacity, would double that size to 360 bytes. Animating more properties, adding more keyframes, and applying changes to multiple objects would increase the exported file size proportionally.

It's important, therefore, to consider the costs of animating even SWF-native properties. Fortunately, you can vary your frame rate without adjusting the duration of your animations, letting you find the balance between a smooth animation and a small file size.