Each animation you create for a Microsoft Agent character is composed of a timed sequence of frames. Each frame in the animation is composed of one or more bitmap images. Images can be as small as you need them or as large as the frame itself.
Animation details such as eye blinking or finger movement can be included as additional images for the frame. You can overlay several images to create a composite, and vary their position in the layers. This technique enables you to reuse images in multiple frames and vary the details that change. For example, if you want to have a character wave its hand, for each frame you could use a base image with everything but the hand and overlay the base image with a different hand image. Similarly, if you want to make the character blink, you can overlay a different set of eyes over a base image for each frame. Images can also be offset from the base image. However, only the part of the image that exists within the frame's size will be displayed.
You can have as many frames in an animation as you wish; however, a typical animation averages about 14 frames so that it plays for no more than 6 seconds. This modest length of time ensures that your character appears responsive to user input. In addition, the greater the number of frames, the larger your animation file. For downloaded Web-based characters, keep the size of your animation file as small as possible while still providing a reasonably-sized set of frames, so that the character's animation does not appear jerky.