MPEG-4 Structured Audio

Mihir Anandpara

EE 382C – Embedded Software Systems

Overview

Structured Audio Systems Audio Synthesis and Effects processing

in MPEG-4 AudioBIFS layer in MPEG-4 Software Implementation and Results Conclusions and Future Work

Structured Audio

Structured Coding v/s Traditional Coding Audio Synthesis through programs

Structured Audio in MPEG-4

Structured Audio Orchestra Language – SAOL• Run-time control of sound through score

• Audio rate and Control rate separation

• Custom effects processing on sound signal

AudioBIFS

Audio Binary Information For Scene Description

Audio Composition, Effects Processing and Virtual Reality Modeling

Scene Graph setup

Example

AudioFX node

Download of custom effects post-processing on the composited/decoded sound signal

Examples:• Simple echo

• Reverberation

• Chorus

Complexity of Effects processing algorithms

Critical issue in studying implementation of an execution engine for effects processing

Complexity Vector • Core Opcode calls

• Floating point divides, multiplies

• Memory accesses

Software Implementation

Scene Graph setup AudioMix, AudioSwitch, AudioDelay

nodes for sound composition Flexible and scalable signal processing

engine for AudioFX node to implement several effects

Results

Implementation of a subset of the AudioBIFS system

SAOL execution engine for AudioFX Complexity analysis of typical effects

processing algorithms Investigation of parallel execution of

effects processing algorithms

Future Work

Implementation of block-based signal processing at control rate

Questions?