ression algorithms in error-prone environments at low bit-rates (i.e., less than 64 Kbps). Tools are provided that address both the band-limited nature and error resiliency aspects for access over wireless networks. The Face Animation part of the standard allows sending parameters that calibrate and animate synthetic faces. Tools TwinVQ Wave- General Algo- Scalable table rithmic thetic synth- Synthesis & Audio MPEG-2 AAC Main MPEG- 2AAC LC MPEG- 2AAC SSR MPEG Family of Specifications Noise Shaping Long Term Prediction Tools for Large Step Scalability TwinVQ Structured Audio tools SA Sample Format Figure Appendix B-5. MPEG-4 Tools MPEG-4 only standardizes the parameters of these models, not the models themselves. MPEG-4 Parts The MPEG-4 requirements have been addressed by the six parts of the MPEG-4 Version 1 standard: Part 1: Systems - specifies scene description, multiplexing, synchronization, buffer management, and management and protection of intellectual property Part 2: Visual - specifies coded representation of natural & synthetic visual objects Part 3: Audio - specifies the coded representation of natural and synthetic audio objects Part 4: Conformance Testing - defines conformance conditions for bitstreams and devices; this part is used to test MPEG-4 implementations Part 5: Reference Software - includes software corresponding to most parts of MPEG-4 (normative and non-normative tools); it can be used for implementing compliant products as ISO waives the copyright of the code Part 6: Delivery Multimedia Integration Framework (DMIF) - defines a session Video Communications: The Whole Picture protocol for the management of multimedia streaming over generic delivery technologies. Parts 1-3 and 6 specify the core MPEG-4 technology; Parts 4 and 5 are supporting parts. Parts 1, 2 and 3 are delivery independent, leaving to Part 6 (DMIF) the task of dealing with the idiosyncrasies of the delivery layer. The MPEG-4 parts are independent and can be used independently or in conjunction with proprietary technologies.