Audio Processes

Book description

Designed for music technology students, enthusiasts, and professionals, Audio Processes: Musical Analysis, Modification, Synthesis, and Control describes the practical design of audio processes, with a step-by-step approach from basic concepts all the way to sophisticated effects and synthesizers. The themes of analysis, modification, synthesis, and control are covered in an accessible manner and without requiring extensive mathematical skills. The order of material aids the progressive accumulation of understanding, but topics are sufficiently contained that those with prior experience can read individual chapters directly.

Extensively supported with block diagrams, algorithms, and audio plots, the ideas and designs are applicable to a wide variety of contexts. The presentation style enables readers to create their own implementations, whatever their preferred programming language or environment. The designs described are practical and extensible, providing a platform for the creation of professional quality results for many different audio applications.

There is an accompanying website (www.routledge.com/cw/creasey), which provides further material and examples, to support the book and aid in process development.

This book includes:

  • A comprehensive range of audio processes, both popular and less well known, extensively supported with block diagrams and other easily understood visual forms.
  • Detailed descriptions suitable for readers who are new to the subject, and ideas to inspire those with more experience.
  • Designs for a wide range of audio contexts that are easily implemented in visual dataflow environments, as well as conventional programming languages.

Table of contents

  1. Cover
  2. Half Title
  3. Title
  4. Copyright
  5. Contents
  6. Abbreviations
  7. Preface
  8. Acknowledgements
  9. Chapter 1 Introduction
    1. 1.1 The Nature of Audio Processes
      1. 1.1.1 Introducing Audio Processes
      2. 1.1.2 Constructing an Audio Process
      3. 1.1.3 Real-Time and Non-Real-Time Systems
      4. 1.1.4 Audio Process Themes
    2. 1.2 Example Audio Process Systems
      1. 1.2.1 Playing an Acoustic Instrument
      2. 1.2.2 Combining Two Paths
      3. 1.2.3 Automated Analysis
      4. 1.2.4 Two Humans Working Together
  10. PART I — ANALYSIS
    1. Chapter 2 Audio Data Fundamentals
      1. 2.1 The Nature of Sound
        1. 2.1.1 Sound in the Time Domain
        2. 2.1.2 Cycle Length, Frequency, and Amplitude
        3. 2.1.3 Construction and Deconstruction with Sinusoids
      2. 2.2 Sound as Numbers
        1. 2.2.1 Overview
        2. 2.2.2 Sampling Continuous Data
        3. 2.2.3 A Complete Digital Audio System
        4. 2.2.4 Choosing a Sample Rate
        5. 2.2.5 Amplitude
    2. Chapter 3 Time Domain Analysis
      1. 3.1 Basic Concepts
        1. 3.1.1 Continuum of Sound Character
        2. 3.1.2 Harmonic Sounds
        3. 3.1.3 Inharmonic Sounds
        4. 3.1.4 Phase Effects
      2. 3.2 Dynamic Sound Character
        1. 3.2.1 Chime Bar
        2. 3.2.2 Amplitude Envelopes
        3. 3.2.3 Dynamic Waveform Changes
        4. 3.2.4 Oboe
        5. 3.2.5 Vibraphone
        6. 3.2.6 Piano
        7. 3.2.7 Tubular Bell
        8. 3.2.8 Vocal "sh" and "f" Sounds
      3. 3.3 Using Time Domain information
      4. 3.4 Learning More
    3. Chapter 4 Frequency Domain Analysis
      1. 4.1 Introduction
      2. 4.2 Static and Average Sound Character
        1. 4.2.1 Spectral Form
        2. 4.2.2 Frequency Domain Analysis of Simple Waveform Shapes
        3. 4.2.3 Average Spectrum Analysis Examples
      3. 4.3 Dynamic Sound Character
        1. 4.3.1 Representing Three Dimensions
        2. 4.3.2 Simple Spectrogram Examples
        3. 4.3.3 More Complex Spectrogram Examples
      4. 4.4 Using Frequency Domain Information
      5. 4.5 Learning More
  11. PART II — MODIFICATION
    1. Chapter 5 Basic Modifications
      1. 5.1 Introduction
      2. 5.2 Signal Flow Control
      3. 5.3 Amplitude Control
        1. 5.3.1 Simple Amplitude Control
        2. 5.3.2 Two Channel Amplitude Control
        3. 5.3.3 Naturalistic Amplitude Control
        4. 5.3.4 Working with Decibels
      4. 5.4 Mixing
      5. 5.5 Pan Control and Stereo Balance
        1. 5.5.1 Monophonic and Stereophonic Signals
        2. 5.5.2 Panning
        3. 5.5.3 Stereo Balance
      6. 5.6 Combination of Elements
        1. 5.6.1 Ordering
        2. 5.6.2 Series and Parallel Forms
        3. 5.6.3 Practical Combination Examples
      7. 5.7 Developing Processes and Learning More
    2. Chapter 6 Filtering
      1. 6.1 Introduction
        1. 6.1.1 Filters and Audio Processes
        2. 6.1.2 Filtering and Acoustic Sound Sources
        3. 6.1.3 Musical Frequency Ranges
        4. 6.1.4 Frequency (Magnitude) Responses
      2. 6.2 Standard Filters
        1. 6.2.1 Lowpass and Highpass Filters
        2. 6.2.2 Bandpass and Bandreject Filters
        3. 6.2.3 Comb and Allpass Filters
        4. 6.2.4 Variations in Filter Responses
      3. 6.3 Filter Combinations
        1. 6.3.1 Common Series and Parallel Forms
        2. 6.3.2 Subtractive Techniques
      4. 6.4 Filter Designs
        1. 6.4.1 Introduction
        2. 6.4.2 Lowpass and Highpass Designs
        3. 6.4.3 Bandpass and Bandreject Designs
        4. 6.4.4 Comb and Allpass Designs
      5. 6.5 Developing Processes and Learning More
    3. Chapter 7 Distortion
      1. 7.1 Introduction
        1. 7.1.1 Avoiding and Creating Distortion
        2. 7.1.2 Hard Clipping
      2. 7.2 Distortion Functions
        1. 7.2.1 Soft Clipping Distortion
        2. 7.2.2 Other Distortion Transfer Functions
        3. 7.2.3 Controlling Distortion Character
      3. 7.3 Distortion of Complex Signals
      4. 7.4 Developing Processes and Learning More
    4. Chapter 8 Audio Data Techniques
      1. 8.1 Storing and Accessing Audio Data
        1. 8.1.1 Storage and Processing Requirements
        2. 8.1.2 Simple Buffering
        3. 8.1.3 Shift Registers and Circular Buffers
        4. 8.1.4 Delayed Sound
        5. 8.1.5 Pointer Position Considerations
      2. 8.2 Selecting and Interpolating Values
        1. 8.2.1 Introduction
        2. 8.2.2 Truncation and Rounding
        3. 8.2.3 Linear Interpolation
        4. 8.2.4 Non-linear Interpolation
      3. 8.3 Level Measurement
        1. 8.3.1 Introduction
        2. 8.3.2 Accurate Peak Measurement
        3. 8.3.3 Accurate RMS Measurement
        4. 8.3.4 Filter-Based Techniques
        5. 8.3.5 Ramping Techniques
        6. 8.3.6 Selecting and Configuring Envelope Followers
      4. 8.4 Developing Processes and Learning More
    5. Chapter 9 Modulated Modifiers
      1. 9.1 Introduction
        1. 9.1.1 Variation over Time
        2. 9.1.2 Oscillators
      2. 9.2 Examples of Periodic Modulation
        1. 9.2.1 Tremolo and Autopan
        2. 9.2.2 Filter Modulation
        3. 9.2.3 Vibrato
        4. 9.2.4 Flanger and Phaser
        5. 9.2.5 Chorus
        6. 9.2.6 Modulated Modulators
      3. 9.3 Developing Processes and Learning More
    6. Chapter 10 Acoustic Environment
      1. 10.1 Basic Concepts
        1. 10.1.1 Types of Environmental Effects
        2. 10.1.2 Fundamentals of Sound in Enclosed Spaces
        3. 10.1.3 Practical Enclosed Spaces
      2. 10.2 Non-Recirculating Echo and Reverberation Forms
        1. 10.2.1 A Simple Model
        2. 10.2.2 Echo Effects
        3. 10.2.3 Multitap Implementation
        4. 10.2.4 Improvements to Echo Effects
        5. 10.2.5 Reverberation Effects
        6. 10.2.6 Convolution with Impulse Responses
      3. 10.3 Recirculating Echo Forms
        1. 10.3.1 Basic Concepts
        2. 10.3.2 Echo Effects
        3. 10.3.3 Improvements to Echo Effects
      4. 10.4 Recirculating Reverberation Forms
        1. 10.4.1 Basic Concepts
        2. 10.4.2 Reverberator with Comb and Allpass Filters
        3. 10.4.3 Multi-Stage Reverberator
        4. 10.4.4 Improvements to the Multi-Stage Reverberator
        5. 10.4.5 Stereo Reverberation
      5. 10.5 Developing Processes and Learning More
    7. Chapter 11 Dynamics Processes
      1. 11.1 Introduction
        1. 11.1.1 Manual and Automated Control Loops
        2. 11.1.2 Amplitude Dynamics
        3. 11.1.3 Basic Forms
      2. 11.2 Noise Gates
        1. 11.2.1 Main Principles
        2. 11.2.2 Simple Form
        3. 11.2.3 Improvements to the Simple Form
        4. 11.2.4 Additional Techniques
      3. 11.3 Compressors
        1. 11.3.1 Main Principles
        2. 11.3.2 Compressor Form
      4. 11.4 Further Techniques
        1. 11.4.1 Expanders
        2. 11.4.2 Sidechain Filtering
        3. 11.4.3 Combinations
        4. 11.4.4 Other Modifications
      5. 11.5 Developing Processes and Learning More
    8. Chapter 12 Frequency Domain Methods
      1. 12.1 Time Domain and Frequency Domain Processes
        1. 12.1.1 Introduction
        2. 12.1.2 Fourier Transform Basics
      2. 12.2 General Techniques
        1. 12.2.1 Filtering
        2. 12.2.2 Vocoding and Application of Spectral Envelopes
        3. 12.2.3 Delay
      3. 12.3 More Sophisticated Techniques
        1. 12.3.1 Time-Stretching
        2. 12.3.2 Changing Pitch
        3. 12.3.3 Modifying Amplitude and Frequency Relationships
        4. 12.3.4 Blending and Morphing
      4. 12.4 Developing Processes and Learning More
  12. PART III — SYNTHESIS
    1. Chapter 13 Basic Synthesis
      1. 13.1 Basic Concepts
        1. 13.1.1 From Modifiers to Synthesizers
        2. 13.1.2 Oscillators
        3. 13.1.3 Note Numbers and Frequency Values
        4. 13.1.4 Parameter Variation
      2. 13.2 Gate and Envelope Methods
        1. 13.2.1 Basic Methods
        2. 13.2.2 Envelope Shapes and Applications
        3. 13.2.3 Audio Input Methods
      3. 13.3 Tremolo and Vibrato in Synthesis
      4. 13.4 Developing Processes and Learning More
    2. Chapter 14 Signal Generators and Shaping
      1. 14.1 Introduction
      2. 14.2 Equation-Based Methods
        1. 14.2.1 Basic Concepts
        2. 14.2.2 Example Equations
      3. 14.3 Breakpoint Methods
        1. 14.3.1 Basic Concepts
        2. 14.3.2 Generating a Single Linear Segment
        3. 14.3.3 Generating Multiple Segments
        4. 14.3.4 Mapping with Multiple Breakpoints
      4. 14.4 Wavetable Methods
        1. 14.4.1 Creating a Wavetable
        2. 14.4.2 Using a Wavetable
        3. 14.4.3 Efficiency and Control
      5. 14.5 Modifying and Shaping Oscillation
        1. 14.5.1 Bandlimiting and Aliasing
        2. 14.5.2 Developing Oscillator Character
        3. 14.5.3 Waveshaping
      6. 14.6 Developing Processes and Learning More
    3. Chapter 15 Sample-Based Synthesis Methods
      1. 15.1 Basic Concepts
        1. 15.1.1 Using Sampled Sound
        2. 15.1.2 Recording, Editing, and Organising Samples
        3. 15.1.3 Sample Playback
      2. 15.2 Position Control and Concatenation
        1. 15.2.1 Position Control and Looping
        2. 15.2.2 Concatenation
        3. 15.2.3 Process Considerations
      3. 15.3 Manipulating Sample Data Values
        1. 15.3.1 Sample Increment Effects
        2. 15.3.2 Further Methods
      4. 15.4 Developing Processes and Learning More
    4. Chapter 16 Additive Synthesis
      1. 16.1 Basic Concepts
        1. 16.1.1 Additive Synthesis Characteristics
        2. 16.1.2 Frequency Separation
      2. 16.2 Synthesis with Control over Individual Partials
        1. 16.2.1 Synthesizer Form
        2. 16.2.2 Configuration from Theory
        3. 16.2.3 Configuration from Sound Analysis
        4. 16.2.4 Abstract Configuration
      3. 16.3 Synthesis with Mapped Control over Multiple Partials
      4. 16.4 Developing Processes and Learning More
    5. Chapter 17 Subtractive Synthesis
      1. 17.1 Basic Concepts
      2. 17.2 Common Subtractive Methods
        1. 17.2.1 Source Selection
        2. 17.2.2 Filtering Methods
      3. 17.3 Vocal Synthesis
        1. 17.3.1 Introduction
        2. 17.3.2 Voiced Source Sound Generation
        3. 17.3.3 Formant Filtering
      4. 17.4 High Resonance Methods
      5. 17.5 Developing Processes and Learning More
    6. Chapter 18 Noise in Synthesis
      1. 18.1 Consistent and Inconsistent Signals
      2. 18.2 Noise in the Time Domain
        1. 18.2.1 Generation and Shaping
        2. 18.2.2 Rate-Controlled Random Value Generation
        3. 18.2.3 Inconsistent Oscillation
      3. 18.3 Noise in the Frequency Domain
        1. 18.3.1 Spectral Envelopes
        2. 18.3.2 Rate Control and Modulation
        3. 18.3.3 Filtering
        4. 18.3.4 Applications
      4. 18.4 Developing Processes and Learning More
    7. Chapter 19 Blending Synthesized Sounds
      1. 19.1 Basic Concepts
      2. 19.2 Fixed Parameter Blends
        1. 19.2.1 Static Blend
        2. 19.2.2 Enhancements to Static Blend
      3. 19.3 Envelope-Controlled Blends
      4. 19.4 Cross-Fading
        1. 19.4.1 Two Signal Cross-Fade
        2. 19.4.2 Four Signal Cross-Fade
        3. 19.4.3 Eight Signal Cross-Fade
      5. 19.5 Developing Processes and Learning More
    8. Chapter 20 Modulation for Synthesis
      1. 20.1 Introduction
      2. 20.2 Amplitude Modulation
        1. 20.2.1 Basic Principles
        2. 20.2.2 Practical Examples
      3. 20.3 Frequency Modulation
        1. 20.3.1 Basic Principles
        2. 20.3.2 Parallel FM
        3. 20.3.3 Multiple Modulator FM Arrangements
      4. 20.4 Further Modulation Methods
      5. 20.5 Developing Processes and Learning More
    9. Chapter 21 Waveguide Physical Models
      1. 21.1 Introduction
        1. 21.1.1 Basic Concepts
        2. 21.1.2 Structure of a Physical Model
        3. 21.1.3 Waveguides
      2. 21.2 Waveguide Plucked String
        1. 21.2.1 Simplest Plucked String
        2. 21.2.2 Body Resonances
        3. 21.2.3 Modifying the Excitation
        4. 21.2.4 Modifying the Waveguide Filtering
      3. 21.3 Waveguides for Percussion
        1. 21.3.1 Banded Waveguides
        2. 21.3.2 Waveguide Mesh Drum
      4. 21.4 Waveguide Wind Instrument
        1. 21.4.1 Basic Wind Instrument
        2. 21.4.2 Breath Input Improvements
        3. 21.4.3 Filtering and Tuning Improvements
      5. 21.5 Bowed Waveguides
      6. 21.6 Developing Processes and Learning More
    10. Chapter 22 Granular Synthesis
      1. 22.1 Sound from Grains
        1. 22.1.1 Introduction
        2. 22.1.2 Granular Stream Generation
        3. 22.1.3 Lookup Table Sources
        4. 22.1.4 Parameter Relationships
      2. 22.2 Granular Synthesis Techniques
        1. 22.2.1 Fixed Parameters
        2. 22.2.2 Envelope Control
        3. 22.2.3 Random Variations
        4. 22.2.4 Parallel Streams
      3. 22.3 Developing Processes and Learning More
  13. PART IV — CONTROL
    1. Chapter 23 Process Organisation and Control
      1. 23.1 Components of organisation and Control
        1. 23.1.1 Introduction
        2. 23.1.2 Process Segmentation
        3. 23.1.3 Processing at Different Rates
        4. 23.1.4 Control Inputs and Mapping
      2. 23.2 Controlling Synthesis
        1. 23.2.1 Introduction
        2. 23.2.2 Polyphonic Methods
        3. 23.2.3 Monophonic Methods
      3. 23.3 Developing Processes and Learning More
    2. Chapter 24 Control Mapping
      1. 24.1 Frequency and Amplitude
        1. 24.1.1 Frequency Control
        2. 24.1.2 Amplitude Gain Control
        3. 24.1.3 Key Velocity to Amplitude Gain
        4. 24.1.4 Further Mapping Considerations
      2. 24.2 More Sophisticated Techniques
        1. 24.2.1 Mapping to Varying Parameters
        2. 24.2.2 Mapping to Multiple Parameters
      3. 24.3 Developing Processes and Learning More
  14. Next Steps
  15. APPENDICES
    1. Appendix A Mathematics for Audio Processes
      1. A.1 The Need for Mathematics
      2. A.2 Variables, Simple Equations, Subscripts, Superscripts
      3. A.3 Repeated Summation
      4. A.4 Linear Mapping
      5. A.5 Straight Lines
      6. A.6 Logarithmic and Exponential Functions
      7. A.7 Mapping and Shaping Functions
      8. A.8 Units, Prefixes, and Symbols
      9. A.9 Accuracy
      10. A.10 Answers to Problems
    2. Appendix B Windowing and Window Functions
      1. B.1 Introduction
      2. B.2 Some Common Window Functions
      3. B.3 Learning More
    3. Appendix C Block Diagram Techniques
      1. C.1 Detail and Clarity
      2. C.2 Relating Diagrams and Programming Forms
  16. Index

Product information

  • Title: Audio Processes
  • Author(s): David Creasey
  • Release date: September 2016
  • Publisher(s): Routledge
  • ISBN: 9781317329176