DAFX - Digital Audio Effects

Transcription

1 DAFX - Digital Audio Effects Udo Zölzer, Editor University of the Federal Armed Forces, Hamburg, Germany Xavier Amatriain Pompeu Fabra University, Barcelona, Spain Daniel Arfib CNRS - Laboratoire de Mecanique et d'acoustique, Marseille, France Jordi Bonada Pompeu Fabra University, Barcelona, Spain Giovanni De Poli University of Padova, Italy Pierre Dutilleux Lübeck, Germany Gianpaolo Evangelista Swiss Federal Institute of Technology Lausanne (EPFL), Switzerland Florian Keiler University of the Federal Armed Forces, Hamburg, Germany Alex Loscos Pompeu Fabra University, Barcelona, Spain Davide Rocchesso University of Verona, Italy Mark Sandler Queen Mary, University of London, United Kingdom Xavier Serra Pompeu Fabra University, Barcelona, Spain Todor Todoroff Brussels, Belgium JOHN WILEY & SONS, LTD

2 Contents Preface List of Contributors xiv xvi 1 Introduction 1 U. Zölzer 1.1 Digital Audio Effects DAFX with MATLAB Fundamentals of Digital Signal Processing Digital Signals Spectrum Analysis of Digital Signals Digital Systems Conclusion 29 Bibliography 29 2 Filters 31 P. Dutilleux, U. Zölzer 2.1 Introduction Basic Filters Lowpass Filter Topologies Parametric AP, LP, HP, BP and BR Filters FIR Filters Convolution Equalizers Shelving Filters Peak Filters Time-varying Filters 55

3 2.4.1 Wah-wah Filter Phaser Time-varying Equalizers Conclusion 59 Sound and Music 59 Bibliography 60 3 Delays 63 P. Dutilleux, U. Zölzer 3.1 Introduction Basic Delay Structures FIR Comb Filter IIR Comb Filter Universal Comb Filter Fractional Delay Lines Delay-based Audio Effects Vibrato Flanger, Chorus, Slapback, Echo Multiband Effects Natural Sounding Comb Filter Conclusion 73 Sound and Music 73 Bibliography 73 4 Modulators and Demodulators 75 P. Dutilleux, U. Zölzer 4.1 Introduction Modulators Ring Modulator Amplitude Modulator Single-Side Band Modulator Frequency and Phase Modulator Demodulators Detectors Averagers Amplitude Scalers 84

4 Contents vii Typical Applications Applications Vibrato Stereo Phaser Rotary Loudspeaker Effect SSB Effects Simple Morphing: Amplitude Following Conclusion 90 Sound and Music 91 Bibliography 91 5 Nonlinear Processing 93 P. Dutilleux, U. Zölzer 5.1 Introduction Dynamics Processing Limiter Compressor and Expander Noise Gate De-esser Infinite Limiters Nonlinear Processors Basics of Nonlinear Modeling Valve Simulation Overdrive, Distortion and Fuzz Harmonic and Subharmonic Generation Tape Saturation Exciters and Enhancers Exciters Enhancers Conclusion 132 Sound and Music 133 Bibliography 133

5 viii Contents 6 Spatial Effects. 137 D. Rocchesso 6.1 Introduction Basic Effects Panorama Precedence Effect Distance and Space Rendering Doppler Effect Sound Trajectories D with Headphones Localization Interaural Differences Externalization Head-Related Transfer Functions D with Loudspeakers Introduction Localization with Multiple Speakers D Panning Ambisonics and Holophony Transaural Stereo Room-Within-the-Room Model Reverberation Acoustic and Perceptual Foundations Classic Reverberation Tools Feedback Delay Networks Convolution with Room Impulse Responses Spatial Enhancements Stereo Enhancement Sound Radiation Simulation Conclusion 193 Sound and Music 193 Bibliography 194

6 Contents ix 7 Time-segment Processing 201 P. Dutilleux, G. De Poli, U. Zölzer 7.1 Introduction Variable Speed Replay Time Stretching Historical Methods - Phonogene Synchronous Overlap and Add (SOLA) Pitch-synchronous Overlap and Add (PSOLA) Pitch Shifting Historical Methods - Harmonizer Pitch Shifting by Time Stretching and Resampling Pitch Shifting by Delay Line Modulation Pitch Shifting by PSOLA and Formant Preservation Time Shuffling and Granulation Time Shuffling Granulation Conclusion 232 Sound and Music 233 Bibliography Time-frequency Processing 237 D. Arüb, F. Keiler, U. Zölzer 8.1 Introduction Phase Vocoder Basics Filter Bank Summation Model Block-by-Block Analysis/Synthesis Model Phase Vocoder Implementations Filter Bank Approach Direct FFT/IFFT Approach FFT Analysis/Sum of Sinusoids Approach Gaboret Approach Phase Unwrapping and Instantaneous Frequency Phase Vocoder Effects Time-frequency Filtering Dispersion 266

7 x Contents Time Stretching Pitch Shifting Stable/Transient Components Separation Mutation between Two Sounds Robotization Whisperization Denoising Conclusion 294 Bibliography Source-Filter Processing 299 D. Arßb, F. Keiler, U. Zölzer 9.1 Introduction Source-Filter Separation Channel Vocoder Linear Predictive Coding (LPC) Cepstrum Source-Filter Transformations Vocoding or Cross-synthesis Formant Changing Spectral Interpolation Pitch Shifting with Formant Preservation Feature Extraction Pitch Extraction Other Features Conclusion 370 Bibliography Spectral Processing 373 X. Amatriain, J. Bonada, A. Loscos, X. Serra 10.1 Introduction Spectral Models Sinusoidal Model Sinusoidal plus Residual Model Techniques Analysis 379

8 Contents xi Feature Analysis Synthesis Main Analysis-Synthesis Application FX and Transformations Filtering with Arbitrary Resolution Partial Dependent Frequency Scaling Pitch Transposition with Timbre Preservation Vibrato and Tremolo Spectral Shape Shift Gender Change Harmonizer Hoarseness Morphing Content-Dependent Processing Real-time Singing Voice Conversion Time Scaling Conclusion 435 Bibliography Time and Frequency Warping Musical Signals 439 G. Evangelista 11.1 Introduction Warping Time Warping Frequency Warping Algorithms for Warping Short-time Warping and Real-time Implementation Time-varying Frequency Warping Musical Uses of Warping Pitch Shifting Inharmonic Sounds Inharmonizer Comb Filtering+Warping and Extraction of Excitation Signals in Inharmonic Sounds Vibrato, Glissando, Trill and Flatterzunge Morphing Conclusion 462 Bibliography 462

9 xii Contents 12 Control of Digital Audio Effects 465 T. Todoroff 12.1 Introduction General Control Issues Mapping Issues Assignation Scaling GUI Design and Control Strategies General GUI Issues A Small Case Study Specific Real-time Control Issues GUI Mapping Issues GUI Programming Languages Algorithmic Control Abstract Models Physical Models Control Based on Sound Features Feature Extraction Examples of Controlling Digital Audio Effects Gestural Interfaces MIDI Standard Playing by Touching and Holding the Instrument Force-feedback Interfaces Interfaces Worn on the Body Controllers without Physical Contact Conclusion 488 Sound and Music 490 Bibliography Bitstream Signal Processing 499 M. Sandler, U. Zölzer 13.1 Introduction Sigma Delta Modulation A Simple Linearized Model of SDM A First-order SDM System 504

10 Contents хш Second and Higher Order SDM Systems BSP Filtering Concepts Addition and Multiplication of Bitstream Signals SD IIR Filters SD FIR Filters Conclusion 511 Bibliography 511 Glossary 515 Bibliography 524 Index 525