SNHC Audio and Audio Composition 23 24 25 26 27 28 29 30 31 32 33 sourceWarmth 3.0 sourceBrilliance 0.5 roomPresence 0.5 runningReverberance 0.1 envelopment 0.1 lateReverberance 3.5 heavyness 2.0 liveness 0.5 } } } 466 Summary In this chapter, the MPEG-4 audio SNHC and composition tools were presented. The SNHC frame- work enables both synthetic and natural audio, as well as digital sound effects, to be included in a single MPEG-4 presentation. The main tools for synthetic audio coding, structured audio (SA), and the text-to-speech interface (TTSI), were presented. Finally, the tools related to the composition and presentation of sound that are defined in the Systems part of MPEG-4 were discussed. These tools are known as AudioBIFS and its extension, Advanced AudioBIFS. The application areas of the MPEG-4 SNHC audio and audio composition tools range from digital sound synthesis and TTS synthesis to postprocessing and mixing of natural and synthetic audio, and to interactive 3D audiovisual environments for virtual and augmented reality. References