MPEG-4 Structured Audio

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MPEG-4 Structured Audio

• Mihir Anandpara
• EE 382C Embedded Software Systems

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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

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Structured Audio

• Structured Coding v/s Traditional Coding
• Audio Synthesis through programs

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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

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AudioBIFS

• Audio Binary Information For Scene Description
• Audio Composition, Effects Processing and Virtual
  Reality Modeling
• Scene Graph setup

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Example
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AudioFX node

• Download of custom effects post-processing on the
  composited/decoded sound signal
• Examples
• Simple echo
• Reverberation
• Chorus

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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

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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

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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

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Future Work

• Implementation of block-based signal processing
  at control rate

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Questions?