Digital Audio Processor

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Digital Audio Processor

• William Buttinger and Dimitri Podoliev

2
Project Overview

• Highly customizable digital audio system
• Provide pre-built effects packages with
  user-specifiable parameters
• Use audio building blocks with the packages to
  create unique effects
• Use a computer to configure the processor

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Overall Block Diagram
Module1
Module2
ModuleN

Signal_outN
Signal_out1
parametersN
parameters1
18
18
18
18
Signal_inN
Signal_in1
input1
Analog_In1
Interconnect Architecture
Input1
RS232
reprogram
computer
Reprogram Controller
params1
Analog_In2
Input2
. .
inputN
Analog_InN
InputN
paramsN
18
18
18
18
Left_in
right_in
Left_out
right_out
Codec Controller
SDATA_IN
SDATA_OUT
Bit_clock
AC97
To all modules
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Interconnect Architecture

• Asynchronous Interconnect

• Router provides most flexibility

• Reprogramming done by
• synchronized FSM.

• Control Bit controls a tristate buffer

Control bit
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Modules
Module Name
Parameters
Delay Duration, Level, Feedback
Band Pass Central Frequency, Width
Compressor Threshold, Ratio, Attack time,
Release Time
Expander Threshold, Ratio, Attack time,
Release Time
Mixer -
Multiplier Co-efficient
..More?
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Theoretical Implementation of FiltersSignal
Processing

• Digital filters implementation
• IIR (Infinite Impulse Response)
• FIR (Finite Impulse Response)

• Design Path of an IIR filter
• Bode plot
• Transfer Function
• Impulse Response
• Z-transform
• Difference equation
• Verilog implementation using modular blocks

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Implementation of a single pole Low Pass Filter

• Transfer function

• Difference equation

• Implementation diagram

• Other filters, such as
• High Pass
• Band Pass
• Band Reject
• Can be easily implemented using this building
  block

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Design of a Simple Phaser
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Routing of a Simple Phaser Filter
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• Questions?