Voice Compression and Communications

LAJOS HANZO has coauthored five books on mobile radio communications and published more than 300 research papers on a variety of topics in wireless multimedia communications. He holds a chair in telecommunications at the Department of Electronics and Computer Science, University of Southampton, UK, and he is an IEEE Distinguished Lecturer.F. CLARE A. SOMERVILLE is with the Global Wireless Systems Research Department, Bell Laboratories, Swindon, UK. His current research involves real-time techniques for transmission of voice over GPRS and the resultant speech quality attained.JASON P. WOODARD is with UbiNetics Ltd., where he is responsible for the development and implementation of various algorithms for third-generation mobile communications products.

• Preface xxiiiAcknowledgments xxixPart I Speech Signals and Waveform Coding 1Chapter 1 Speech Signals and Introduction to Speech Coding 31.1 Motivation of Speech Compression 31.2 Basic Characterization of Speech Signals 41.3 Classification of Speech Codecs 71.4 Waveform Coding 111.5 Chapter Summary 26Chapter 2 Predictive Coding 272.1 Forward Predictive Coding 272.2 DPCM Codec Schematic 282.3 Predictor Design 292.4 Adaptive One-Word-Memory Quantization 362.5 DPCM Performance 372.6 Backward-Adaptive Prediction 392.7 The 32kbps G.721 ADPCM Codec 432.8 Subjective and Objective Speech Quality 492.9 Variable-Rate G.726 and Embedded G.727 ADPCM 502.10 Rate-Distortion in Predictive Coding 582.11 Chapter Summary 62Part II Analysis by Synthesis Coding 63Chapter 3 Analysis-by-Synthesis Principles 653.1 Motivation 653.2 Analysis-by-Synthesis Codec Structure 663.3 The Short-Term Synthesis Filter 673.4 Long-Term Prediction 703.5 Excitation Models 783.6 Adaptive Short-Term and Long-Term Post-Filtering 813.7 Lattice-Based Linear Prediction 833.8 Chapter Summary 89Chapter 4 Speech Spectral Quantization 904.1 Log-Area Ratios 904.2 Line Spectral Frequencies 954.3 Vector Quantization of Spectral Parameters 1054.4 Spectral Quantizers for Wideband Speech Coding 1134.5 Chapter Summary 126Chapter 5 Regular Pulse Excited Coding 1275.1 Theoretical Background 1275.2 The 13 kbps RPE-LTP GSM Speech Encoder 1335.3 The 13 kbps RPE-LTP GSM Speech Decoder 1375.4 Bit Sensitivity of the 13 kbps GSM RPE-LTP Codec 1405.5 Application Example: A Toolbox-Based Speech Transceiver 1425.6 Chapter Summary 144Chapter 6 Forward-Adaptive Code Excited Linear Prediction 1456.1 Background 1456.2 The Original CELP Approach 1466.3 Fixed Codebook Search 1496.4 CELP Excitation Models 1516.5 Optimization of the CELP Codec Parameters 1606.6 The Error-Sensitivity of CELP Codecs 1756.7 Application Example: A Dual-Mode 3.1 kBd Speech Transceiver 1876.8 Multi-Slot PRMA Transceiver 2006.9 Chapter Summary 206Chapter 7 Standard For ward-Adaptive CELP Codecs 2077.1 Background 2077.2 The U.S. DoD FS-1016 4.8kbits/s CELP Codec 2077.3 The IS-54 DAMPS kbps Pan American Speech Codec 2137.4 The 6.7 kbps Japanese Digital Cellular System's Speech Codec 2167.5 The Qualcomm Variable-Rate CELP Codec 2187.6 Japanese Half-Rate Speech Codec 2257.7 The Half-Rate GSM Codec 2337.8 The 8kbits/s G.729 Codec 2377.9 The Reduced Complexity G.729 Annex A Codec 2567.10 The 12.2 kbps Enhanced Full-Rate GSM Speech Codec 2597.11 The Enhanced Full-Rate 7.4 kbps IS-136 Speech Codec 2647.12 The ITU G.723.1 Dual-Rate Codec 2687.13 Chapter Summary 277Chapter 8 Backward-Adaptive Code Excited Linear Prediction 2798.1 Introduction 2798.2 Motivation and Background 2798.3 Backward-Adaptive G.728 Codec Schematic 2828.4 Backward-Adaptive G.728 Coding Algorithm 2848.5 Reduced-Rate G.728-Like Codec: Variable-Length Excitation Vector 2988.6 The Effects of Long-Term Prediction 3008.7 Closed-Loop Codebook Training 3058.8 Reduced-Rate G.728-Like Codec II: Constant-Length Excitation Vector 3098.9 Programmable-Rate 8-4 kbps Low-Delay CELP Codecs 3108.10 Backward-Adaptive Error Sensitivity Issues 3278.11 A Low-Delay Multimode Speech Transceiver 3338.12 Chapter Summary 338Part III Wideband Coding and Transmission 339Chapter 9 Wideband Speech Coding 3419.1 Sub-band-ADPCM Wideband Coding at 64 kbps 3419.2 Wideband Transform Coding at 32 kbps 3579.3 Sub-Band-Split Wideband CELP Codecs 3609.4 Fullband Wideband ACELP Coding 3639.5 A Turbo-Coded Burst-by-Burst Adaptive Wideband Speech Transceiver 3689.6 Chapter Summary 384Part IV Very Low-Rate Coding and Transmission 385Chapter 10 Overview of Low-Rate Speech Coding 38710.1 Low-Bitrate Speech Coding 38710.2 Linear Predictive Coding Model 40010.3 Speech Quality Measurements 40310.4 Speech Database 40610.5 Chapter Summary 409Chapter 11 Linear Predictive Vocoder 41111.1 Overview of a Linear Predictive Vocoder 41111.2 Line Spectrum Frequencies Quantization 41211.3 Pitch Detection 41711.4 Unvoiced Frames 42811.5 Voiced Frames 42911.6 Adaptive Post-Filter 43011.7 Pulse Dispersion Filter 43211.8 Results for Linear Predictive Vocoder 43711.9 Chapter Summary 440Chapter 12 Wavelets and Pitch Detection 44112.1 Conceptual Introduction to Wavelets 44112.2 Introduction to Wavelet Mathematics 44412.3 Pre-Processing the Wavelet Transform Signal 44912.4 Voiced-Unvoiced Decision 45212.5 Wavelet-Based Pitch Detector 45312.6 Summary and Conclusions 460Chapter 13 Zinc Function Excitation 46113.1 Introduction 46113.2 Overview of Prototype Waveform Interpolation Zinc Function Excitation 46213.3 Zinc Function Modeling 46613.4 Pitch Detection 47013.5 Voiced Speech 47313.6 Excitation Interpolation Between Prototype Segments 47713.7 Unvoiced Speech 48313.8 Adaptive Post-Filter 48313.9 Results for Single Zinc Function Excitation 48313.10 Error Sensitivity of the 1.9kbps PWI-ZFE Coder 48613.11 Multiple Zinc Function Excitation 49013.12 A Sixth-Rate, 3.8kbps GSM-Like Speech Transceiver 49613.13 Chapter Summary 500Chapter 14 Mixed-Multiband Excitation 50114.1 Introduction 50114.2 Overview of Mixed-Multiband Excitation 50214.3 Finite Impulse Response Filter 50414.4 Mixed-Multiband Excitation Encoder 50714.5 Mixed-Multiband Excitation Decoder 51014.6 Performance of the Mixed-Multiband Excitation Coder 51314.7 A Higher Rate 3.85 kbps Mixed-Multiband Excitation Scheme 52014.8 A 2.35kbit/s Joint-Detection-Based CDMA Speech Transceiver 52314.9 Chapter Summary 530Chapter 15 Sinusoidal Transform Coding Below 4kbps 53115.1 Introduction 53115.2 Sinusoidal Analysis of Speech Signals 53215.3 Sinusoidal Synthesis of Speech Signals 53415.4 Low-Bitrate Sinusoidal Coders 53615.5 Incorporating Prototype Waveform Interpolation 53915.6 Encoding the Sinusoidal Frequency Component 54115.7 Determining the Excitation Components 54315.8 Quantizing the Excitation Parameters 54815.9 Sinusoidal Transform Decoder 55615.10 Speech Coder Performance 55815.11 Chapter Summary 563Chapter 16 Conclusions on Low-Rate Coding 56516.1 Overview 56516.2 Listening Tests 56516.3 Summary of Very Low-Rate Coding16.4 Further Research 568Chapter 17 Comparison of Speech Codecs and Transceivers 56917.1 Background to Speech Quality Evaluation 56917.2 Objective Speech Quality Measures 57017.3 Subjective Measures 57717.4 Comparison of Subjective and Objective Measures 57817.5 Subjective Speech Quality of Various Codecs 58017.6 Error Sensitivity Comparison of Various Codecs 58217.7 Objective Speech Performance of Various Transceivers 583Appendix A Constructing the Quadratic Spline Wavelets 589Appendix B Zinc Function Excitation 593Appendix C Probability Density Function for Amplitudes 597Bibliography 601Index 623Author Index 631

"...focuses on voice compression issues in wireless communications." (SciTech Book News, Vol. 25, No. 4, December 2001) "...a treatise on voice compression theory and practice that comprehensively treats this field?s evolution and current state of the art." (Choice, Vol. 39, No. 7, March 2002)"...a definitive reference...no other single reference packs as much valuable and divers information about speech coding in a single volume...a truly invaluable reference..." (Analog Dialogue, Vol. 36, No. 6, November/December 2002)