BIFS, short for BInary Format for Scenes, is the format used by MPEG4 to describe scenes of all sorts. It is based on VRML, the Virtual Reality Modelling Language, and it includes almost all of its functionality plus 2D primitives, facial animation, enhanced audio and streaming of both models and animation. Unlike the raw ASCII text of VRML, the BIFS scene graph is stored in a highly compressed binary format, making files approximately one tenth the size of equivalent VRML scenes. However, since BIFS is closely based on VRML, it should almost always be possible to import VRML scenes into MPEG4 without modification, although the reverse is not necessarily true.
The MPEG4 standard defines a number of different profiles, each implementing a different subset of the full capabilities of the format; the idea is that different players will implement different profiles, and the profiles will be used for different purposes. They are as follows:
- Audio - for audio only scenes.
- Simple 2D - basic scene without many graphical elements.
- Complete 2D - adds backgrounds, bitmaps, circles, boxes and lines in 2D space.
- Complete - adds complete 3D graphical nodes such as sphere, cone, 3D boxes as well as directional lighting.
As of summer 2001, the most complete BIFS/MPEG4 viewer, the SONG Player, was still in development and not commercially available; the beta we were using at the BBC had some way to go before it would do everything MPEG4 was supposed to do.
See also: MPEG4, VRML, Web3D, X3D.