book

Audio Processes

Name: Audio Processes
Author: David Creasey
ISBN: 9781317329176

by David Creasey

September 2016

Intermediate to advanced

752 pages

18h 36m

English

Routledge

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Cover
Half Title
Title
Copyright
Contents
Abbreviations
Preface
Acknowledgements
Chapter 1 Introduction
1.1 The Nature of Audio Processes1.1.1 Introducing Audio Processes1.1.2 Constructing an Audio Process1.1.3 Real-Time and Non-Real-Time Systems1.1.4 Audio Process Themes1.2 Example Audio Process Systems1.2.1 Playing an Acoustic Instrument1.2.2 Combining Two Paths1.2.3 Automated Analysis1.2.4 Two Humans Working Together
PART I — ANALYSIS

Chapter 2 Audio Data Fundamentals
2.1 The Nature of Sound2.1.1 Sound in the Time Domain2.1.2 Cycle Length, Frequency, and Amplitude2.1.3 Construction and Deconstruction with Sinusoids2.2 Sound as Numbers2.2.1 Overview2.2.2 Sampling Continuous Data2.2.3 A Complete Digital Audio System2.2.4 Choosing a Sample Rate2.2.5 Amplitude
Chapter 3 Time Domain Analysis
3.1 Basic Concepts3.1.1 Continuum of Sound Character3.1.2 Harmonic Sounds3.1.3 Inharmonic Sounds3.1.4 Phase Effects3.2 Dynamic Sound Character3.2.1 Chime Bar3.2.2 Amplitude Envelopes3.2.3 Dynamic Waveform Changes3.2.4 Oboe3.2.5 Vibraphone3.2.6 Piano3.2.7 Tubular Bell3.2.8 Vocal "sh" and "f" Sounds3.3 Using Time Domain information3.4 Learning More
Chapter 4 Frequency Domain Analysis
4.1 Introduction4.2 Static and Average Sound Character4.2.1 Spectral Form4.2.2 Frequency Domain Analysis of Simple Waveform Shapes4.2.3 Average Spectrum Analysis Examples4.3 Dynamic Sound Character4.3.1 Representing Three Dimensions4.3.2 Simple Spectrogram Examples4.3.3 More Complex Spectrogram Examples4.4 Using Frequency Domain Information4.5 Learning More
PART II — MODIFICATION
Chapter 5 Basic Modifications
5.1 Introduction5.2 Signal Flow Control5.3 Amplitude Control5.3.1 Simple Amplitude Control5.3.2 Two Channel Amplitude Control5.3.3 Naturalistic Amplitude Control5.3.4 Working with Decibels5.4 Mixing5.5 Pan Control and Stereo Balance5.5.1 Monophonic and Stereophonic Signals5.5.2 Panning5.5.3 Stereo Balance5.6 Combination of Elements5.6.1 Ordering5.6.2 Series and Parallel Forms5.6.3 Practical Combination Examples5.7 Developing Processes and Learning More
Chapter 6 Filtering
6.1 Introduction6.1.1 Filters and Audio Processes6.1.2 Filtering and Acoustic Sound Sources6.1.3 Musical Frequency Ranges6.1.4 Frequency (Magnitude) Responses6.2 Standard Filters6.2.1 Lowpass and Highpass Filters6.2.2 Bandpass and Bandreject Filters6.2.3 Comb and Allpass Filters6.2.4 Variations in Filter Responses6.3 Filter Combinations6.3.1 Common Series and Parallel Forms6.3.2 Subtractive Techniques6.4 Filter Designs6.4.1 Introduction6.4.2 Lowpass and Highpass Designs6.4.3 Bandpass and Bandreject Designs6.4.4 Comb and Allpass Designs6.5 Developing Processes and Learning More
Chapter 7 Distortion
7.1 Introduction7.1.1 Avoiding and Creating Distortion7.1.2 Hard Clipping7.2 Distortion Functions7.2.1 Soft Clipping Distortion7.2.2 Other Distortion Transfer Functions7.2.3 Controlling Distortion Character7.3 Distortion of Complex Signals7.4 Developing Processes and Learning More
Chapter 8 Audio Data Techniques
8.1 Storing and Accessing Audio Data8.1.1 Storage and Processing Requirements8.1.2 Simple Buffering8.1.3 Shift Registers and Circular Buffers8.1.4 Delayed Sound8.1.5 Pointer Position Considerations8.2 Selecting and Interpolating Values8.2.1 Introduction8.2.2 Truncation and Rounding8.2.3 Linear Interpolation8.2.4 Non-linear Interpolation8.3 Level Measurement8.3.1 Introduction8.3.2 Accurate Peak Measurement8.3.3 Accurate RMS Measurement8.3.4 Filter-Based Techniques8.3.5 Ramping Techniques8.3.6 Selecting and Configuring Envelope Followers8.4 Developing Processes and Learning More
Chapter 9 Modulated Modifiers
9.1 Introduction9.1.1 Variation over Time9.1.2 Oscillators9.2 Examples of Periodic Modulation9.2.1 Tremolo and Autopan9.2.2 Filter Modulation9.2.3 Vibrato9.2.4 Flanger and Phaser9.2.5 Chorus9.2.6 Modulated Modulators9.3 Developing Processes and Learning More
Chapter 10 Acoustic Environment
10.1 Basic Concepts10.1.1 Types of Environmental Effects10.1.2 Fundamentals of Sound in Enclosed Spaces10.1.3 Practical Enclosed Spaces10.2 Non-Recirculating Echo and Reverberation Forms10.2.1 A Simple Model10.2.2 Echo Effects10.2.3 Multitap Implementation10.2.4 Improvements to Echo Effects10.2.5 Reverberation Effects10.2.6 Convolution with Impulse Responses10.3 Recirculating Echo Forms10.3.1 Basic Concepts10.3.2 Echo Effects10.3.3 Improvements to Echo Effects10.4 Recirculating Reverberation Forms10.4.1 Basic Concepts10.4.2 Reverberator with Comb and Allpass Filters10.4.3 Multi-Stage Reverberator10.4.4 Improvements to the Multi-Stage Reverberator10.4.5 Stereo Reverberation10.5 Developing Processes and Learning More
Chapter 11 Dynamics Processes
11.1 Introduction11.1.1 Manual and Automated Control Loops11.1.2 Amplitude Dynamics11.1.3 Basic Forms11.2 Noise Gates11.2.1 Main Principles11.2.2 Simple Form11.2.3 Improvements to the Simple Form11.2.4 Additional Techniques11.3 Compressors11.3.1 Main Principles11.3.2 Compressor Form11.4 Further Techniques11.4.1 Expanders11.4.2 Sidechain Filtering11.4.3 Combinations11.4.4 Other Modifications11.5 Developing Processes and Learning More
Chapter 12 Frequency Domain Methods
12.1 Time Domain and Frequency Domain Processes12.1.1 Introduction12.1.2 Fourier Transform Basics12.2 General Techniques12.2.1 Filtering12.2.2 Vocoding and Application of Spectral Envelopes12.2.3 Delay12.3 More Sophisticated Techniques12.3.1 Time-Stretching12.3.2 Changing Pitch12.3.3 Modifying Amplitude and Frequency Relationships12.3.4 Blending and Morphing12.4 Developing Processes and Learning More
PART III — SYNTHESIS
Chapter 13 Basic Synthesis
13.1 Basic Concepts13.1.1 From Modifiers to Synthesizers13.1.2 Oscillators13.1.3 Note Numbers and Frequency Values13.1.4 Parameter Variation13.2 Gate and Envelope Methods13.2.1 Basic Methods13.2.2 Envelope Shapes and Applications13.2.3 Audio Input Methods13.3 Tremolo and Vibrato in Synthesis13.4 Developing Processes and Learning More
Chapter 14 Signal Generators and Shaping
14.1 Introduction14.2 Equation-Based Methods14.2.1 Basic Concepts14.2.2 Example Equations14.3 Breakpoint Methods14.3.1 Basic Concepts14.3.2 Generating a Single Linear Segment14.3.3 Generating Multiple Segments14.3.4 Mapping with Multiple Breakpoints14.4 Wavetable Methods14.4.1 Creating a Wavetable14.4.2 Using a Wavetable14.4.3 Efficiency and Control14.5 Modifying and Shaping Oscillation14.5.1 Bandlimiting and Aliasing14.5.2 Developing Oscillator Character14.5.3 Waveshaping14.6 Developing Processes and Learning More
Chapter 15 Sample-Based Synthesis Methods
15.1 Basic Concepts15.1.1 Using Sampled Sound15.1.2 Recording, Editing, and Organising Samples15.1.3 Sample Playback15.2 Position Control and Concatenation15.2.1 Position Control and Looping15.2.2 Concatenation15.2.3 Process Considerations15.3 Manipulating Sample Data Values15.3.1 Sample Increment Effects15.3.2 Further Methods15.4 Developing Processes and Learning More
Chapter 16 Additive Synthesis
16.1 Basic Concepts16.1.1 Additive Synthesis Characteristics16.1.2 Frequency Separation16.2 Synthesis with Control over Individual Partials16.2.1 Synthesizer Form16.2.2 Configuration from Theory16.2.3 Configuration from Sound Analysis16.2.4 Abstract Configuration16.3 Synthesis with Mapped Control over Multiple Partials16.4 Developing Processes and Learning More
Chapter 17 Subtractive Synthesis
17.1 Basic Concepts17.2 Common Subtractive Methods17.2.1 Source Selection17.2.2 Filtering Methods17.3 Vocal Synthesis17.3.1 Introduction17.3.2 Voiced Source Sound Generation17.3.3 Formant Filtering17.4 High Resonance Methods17.5 Developing Processes and Learning More
Chapter 18 Noise in Synthesis
18.1 Consistent and Inconsistent Signals18.2 Noise in the Time Domain18.2.1 Generation and Shaping18.2.2 Rate-Controlled Random Value Generation18.2.3 Inconsistent Oscillation18.3 Noise in the Frequency Domain18.3.1 Spectral Envelopes18.3.2 Rate Control and Modulation18.3.3 Filtering18.3.4 Applications18.4 Developing Processes and Learning More
Chapter 19 Blending Synthesized Sounds
19.1 Basic Concepts19.2 Fixed Parameter Blends19.2.1 Static Blend19.2.2 Enhancements to Static Blend19.3 Envelope-Controlled Blends19.4 Cross-Fading19.4.1 Two Signal Cross-Fade19.4.2 Four Signal Cross-Fade19.4.3 Eight Signal Cross-Fade19.5 Developing Processes and Learning More
Chapter 20 Modulation for Synthesis
20.1 Introduction20.2 Amplitude Modulation20.2.1 Basic Principles20.2.2 Practical Examples20.3 Frequency Modulation20.3.1 Basic Principles20.3.2 Parallel FM20.3.3 Multiple Modulator FM Arrangements20.4 Further Modulation Methods20.5 Developing Processes and Learning More
Chapter 21 Waveguide Physical Models
21.1 Introduction21.1.1 Basic Concepts21.1.2 Structure of a Physical Model21.1.3 Waveguides21.2 Waveguide Plucked String21.2.1 Simplest Plucked String21.2.2 Body Resonances21.2.3 Modifying the Excitation21.2.4 Modifying the Waveguide Filtering21.3 Waveguides for Percussion21.3.1 Banded Waveguides21.3.2 Waveguide Mesh Drum21.4 Waveguide Wind Instrument21.4.1 Basic Wind Instrument21.4.2 Breath Input Improvements21.4.3 Filtering and Tuning Improvements21.5 Bowed Waveguides21.6 Developing Processes and Learning More
Chapter 22 Granular Synthesis
22.1 Sound from Grains22.1.1 Introduction22.1.2 Granular Stream Generation22.1.3 Lookup Table Sources22.1.4 Parameter Relationships22.2 Granular Synthesis Techniques22.2.1 Fixed Parameters22.2.2 Envelope Control22.2.3 Random Variations22.2.4 Parallel Streams22.3 Developing Processes and Learning More
PART IV — CONTROL
Chapter 23 Process Organisation and Control
23.1 Components of organisation and Control23.1.1 Introduction23.1.2 Process Segmentation23.1.3 Processing at Different Rates23.1.4 Control Inputs and Mapping23.2 Controlling Synthesis23.2.1 Introduction23.2.2 Polyphonic Methods23.2.3 Monophonic Methods23.3 Developing Processes and Learning More
Chapter 24 Control Mapping
24.1 Frequency and Amplitude24.1.1 Frequency Control24.1.2 Amplitude Gain Control24.1.3 Key Velocity to Amplitude Gain24.1.4 Further Mapping Considerations24.2 More Sophisticated Techniques24.2.1 Mapping to Varying Parameters24.2.2 Mapping to Multiple Parameters24.3 Developing Processes and Learning More
Next Steps
APPENDICES
Appendix A Mathematics for Audio ProcessesA.1 The Need for MathematicsA.2 Variables, Simple Equations, Subscripts, SuperscriptsA.3 Repeated SummationA.4 Linear MappingA.5 Straight LinesA.6 Logarithmic and Exponential FunctionsA.7 Mapping and Shaping FunctionsA.8 Units, Prefixes, and SymbolsA.9 AccuracyA.10 Answers to Problems
Appendix B Windowing and Window Functions
B.1 IntroductionB.2 Some Common Window FunctionsB.3 Learning More
Appendix C Block Diagram Techniques
C.1 Detail and ClarityC.2 Relating Diagrams and Programming Forms
Index

Content preview from Audio Processes

B Windowing and Window Functions

B.1	Introduction
B.2	Some Common Window Functions
B.3	Learning More

The process of extracting a segment of audio from a longer time domain waveform is found in a number of audio processes such as Short Time Fourier Transform (STFT) frequency domain methods (Chapter 12) and granular synthesis (Chapter 22). The purpose of the extraction is such that the segment can be used in isolation. The length of the segment and its position within the source waveform will usually be determined by the configuration of the audio process. It is often impossible to ensure synchrony between the point of extraction and the oscillation of the waveform. It is likely therefore, that the sample values at the ends of the ...

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Audio Processes

by David Creasey

B Windowing and Window Functions

B.1 Introduction

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