A practical handbook of speech coders / Randy Goldberg, Lance Riek

A Practical Handbook of Speech Coders......Page 1
Authors......Page 3
Acknowledgments......Page 5
Table of Contents......Page 6
List of Figures......Page 10
List of Tables......Page 14
1 Introduction......Page 17
2.1 The Speech Chain......Page 21
2.2 Articulation......Page 24
2.2.1 Excitation......Page 25
2.2.2 Vocal Tract......Page 27
2.2.3 Phonemes......Page 30
2.3 Source-Filter Model......Page 45
3.1 Sampling the Speech Waveform......Page 49
3.2 Systems and Filtering......Page 52
3.3 Z-Transform......Page 54
3.4 Fourier Transform......Page 56
3.5 Discrete Fourier Transform......Page 58
3.5.1 Fast Fourier Transform......Page 59
3.6 Windowing Signal Segments......Page 61
4.1 Sound Propagation in the Vocal Tract......Page 67
4.1.1 Multiple-Tube Model......Page 71
4.2 Estimation of LP Parameters......Page 73
4.2.1 Autocorrelation Method of Parameter Estimation......Page 74
4.2.2 Covariance Method......Page 75
4.3.2 Line Spectral Frequencies......Page 76
4.4 Examples of LP Modeling......Page 77
5 Pitch Extraction 65......Page 81
5.1 Autocorrelation Pitch Estimation......Page 82
5.1.1 Autocorrelation of Center-Clipped Speech......Page 84
5.1.2 Cross Correlation......Page 85
5.2 Cepstral Pitch Extraction......Page 88
5.3 Frequency-Domain Error Minimization......Page 92
5.4.1 Median Smoothing......Page 93
5.4.2 Dynamic Programming Tracking......Page 94
6.1 The Basilar Membrane: A Spectrum Analyzer......Page 96
6.2 Critical Bands......Page 97
6.3 Thresholds of Audibility and Detectability......Page 100
6.4.1 Simultaneous Masking in Frequency......Page 102
6.4.2 Temporal Masking......Page 104
7 Quantization and Waveform Coders......Page 107
7.1.1 Uniform Pulse Code Modulation (PCM)......Page 108
7.2 Nonlinear Quantization......Page 111
7.3 Differential Waveform Coding......Page 112
7.3.1 Predictive Differential Coding......Page 114
7.3.2 Delta Modulation......Page 115
7.4.2 Adaptive Differential Pulse Code Modulation (ADPCM)......Page 117
7.5 Vector Quantization......Page 121
7.5.1 Distortion Measures......Page 123
7.5.2 Codebook Training......Page 125
7.5.3 Complexity Reduction Approaches......Page 126
7.5.4 Predictive Vector Quantization......Page 128
8 Quality Evaluation......Page 132
8.1.1 Signal-to-Noise Ratio......Page 133
8.2 Subjective Measures......Page 134
8.2.1 Intelligibility......Page 135
8.2.2 Quality......Page 136
8.2.3 Background Noise and Channel Conditions......Page 138
8.3 Perceptual Objective Measures......Page 139
9 Voice Coding Concepts......Page 142
9.1 Channel Vocoder......Page 144
9.1.1 Implementations of the Channel Vocoder......Page 145
9.2 formant Vocoder......Page 147
9.3.1 The Sinusoidal Model......Page 149
9.3.2 Sinusoidal Parameter Analysis......Page 150
9.4 Linear Prediction Vocoder......Page 152
9.4.1 Federal Standard 1015, LPC-10e at 2.4 kbit/s......Page 156
10 Linear Prediction Analysis by Synthesis......Page 159
10.1 Analysis by Synthesis Estimation of Excitation......Page 160
10.2 Multi-Pulse Linear Prediction Coder......Page 161
10.3 Regular Pulse Excited LP Coder......Page 162
10.4 Code Excited Linear Prediction Coder......Page 163
10.4.1 CELP Concept......Page 165
10.4.2 CELP Computational Efficiency Improvements......Page 166
10.4.3 Adaptive Postfiltering......Page 168
10.4.5 ITU-T G.728 Low Delay CELP at 16 kbit/s......Page 169
10.4.6 ITU G.723.1 algebraic CELP/Multi-Pulse Coder at 5.3/6.3 kbit/s......Page 170
10.4.7 ETSI GSM Enhanced Full Rate Algebraic CELP at 12.2 kbit/s......Page 172
10.4.8 IS-641 EFR 7.4 kbit/s Algebraic CELP for IS-136 North American Digital Cellular......Page 173
10.4.9 ETSI GSM Adaptive Multi-Rate Algebraic CELP from 4.75 to 12.2 kbit/s......Page 174
11.1 Multi-Band Excitation Vocoder......Page 177
11.1.1 Multi-Band Excitation Analysis......Page 178
11.1.2 Multi-Band Excitation synthesis......Page 181
11.1.3 Implementations of the MBE Vocoder......Page 183
11.2 Mixed Excitation Linear Prediction Coder......Page 185
11.2.1 Federal Standard MELP Coder at 2.4 kbit/s......Page 188
11.2.2 Improvements ot MELP Coder......Page 194
11.3 Split Band LPC Coder......Page 196
11.3.1 Bit Allocations and Quality Results......Page 197
11.4.1 HVXC Encoder......Page 199
11.4.2 HVXC Decoder......Page 202
11.5 Waveform Interpolation Coding......Page 205
11.5.1 WI Coder and Decoder......Page 206
11.5.2 quantization of SEW and REW......Page 208
11.5.3 Performance and Enhancements......Page 209
12.1 Auditory Processing of Speech......Page 213
12.1.1 General Perceptual Speech Coder......Page 214
12.1.2 Frequency and Temporal Masking......Page 215
12.1.3 Determining Masking Levels......Page 217
12.2 Perceptual Coding Considerations......Page 219
12.2.2 Sound Quality of Signal Components......Page 220
12.2.3 MBE Model for Perceptual Coding......Page 221
12.3 Research in Perceptual Speech Coding......Page 222
A.1 Information on Coding Standards......Page 226
A.2 Technical Conferences......Page 228
References......Page 231