4.1. Basics of BIFS

After an introduction to the basic concepts of BIFS, the main BIFS features are presented in this section, from the usage point of view.

4.1.1. Scene and Nodes

What the user of the MPEG-4 terminal sees and hears is the scene. The scene has a visual and an audio component. The visual component (i.e., what is on the screen) can be a 2D or a 3D world. A 2D scene is one in which objects have the same visual size regardless of their being in front or in the back. This type of representation is sometimes called 2.5D because, although the objects are flat, they have a depth order, which is a first step toward the third dimension. 3D fanatics would call a 2D world the orthographic projection of a 3D world.

The sound component of a ...

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