1 /* 2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11 12 /* 13 * This file contains the resampling functions between 48, 44, 32 and 24 kHz. 14 * The description headers can be found in signal_processing_library.h 15 * 16 */ 17 18 #include "webrtc/common_audio/signal_processing/include/signal_processing_library.h" 19 20 // interpolation coefficients 21 static const int16_t kCoefficients48To32[2][8] = { 22 {778, -2050, 1087, 23285, 12903, -3783, 441, 222}, 23 {222, 441, -3783, 12903, 23285, 1087, -2050, 778} 24 }; 25 26 static const int16_t kCoefficients32To24[3][8] = { 27 {767, -2362, 2434, 24406, 10620, -3838, 721, 90}, 28 {386, -381, -2646, 19062, 19062, -2646, -381, 386}, 29 {90, 721, -3838, 10620, 24406, 2434, -2362, 767} 30 }; 31 32 static const int16_t kCoefficients44To32[4][9] = { 33 {117, -669, 2245, -6183, 26267, 13529, -3245, 845, -138}, 34 {-101, 612, -2283, 8532, 29790, -5138, 1789, -524, 91}, 35 {50, -292, 1016, -3064, 32010, 3933, -1147, 315, -53}, 36 {-156, 974, -3863, 18603, 21691, -6246, 2353, -712, 126} 37 }; 38 39 // Resampling ratio: 2/3 40 // input: int32_t (normalized, not saturated) :: size 3 * K 41 // output: int32_t (shifted 15 positions to the left, + offset 16384) :: size 2 * K 42 // K: number of blocks 43 44 void WebRtcSpl_Resample48khzTo32khz(const int32_t *In, int32_t *Out, size_t K) 45 { 46 ///////////////////////////////////////////////////////////// 47 // Filter operation: 48 // 49 // Perform resampling (3 input samples -> 2 output samples); 50 // process in sub blocks of size 3 samples. 51 int32_t tmp; 52 size_t m; 53 54 for (m = 0; m < K; m++) 55 { 56 tmp = 1 << 14; 57 tmp += kCoefficients48To32[0][0] * In[0]; 58 tmp += kCoefficients48To32[0][1] * In[1]; 59 tmp += kCoefficients48To32[0][2] * In[2]; 60 tmp += kCoefficients48To32[0][3] * In[3]; 61 tmp += kCoefficients48To32[0][4] * In[4]; 62 tmp += kCoefficients48To32[0][5] * In[5]; 63 tmp += kCoefficients48To32[0][6] * In[6]; 64 tmp += kCoefficients48To32[0][7] * In[7]; 65 Out[0] = tmp; 66 67 tmp = 1 << 14; 68 tmp += kCoefficients48To32[1][0] * In[1]; 69 tmp += kCoefficients48To32[1][1] * In[2]; 70 tmp += kCoefficients48To32[1][2] * In[3]; 71 tmp += kCoefficients48To32[1][3] * In[4]; 72 tmp += kCoefficients48To32[1][4] * In[5]; 73 tmp += kCoefficients48To32[1][5] * In[6]; 74 tmp += kCoefficients48To32[1][6] * In[7]; 75 tmp += kCoefficients48To32[1][7] * In[8]; 76 Out[1] = tmp; 77 78 // update pointers 79 In += 3; 80 Out += 2; 81 } 82 } 83 84 // Resampling ratio: 3/4 85 // input: int32_t (normalized, not saturated) :: size 4 * K 86 // output: int32_t (shifted 15 positions to the left, + offset 16384) :: size 3 * K 87 // K: number of blocks 88 89 void WebRtcSpl_Resample32khzTo24khz(const int32_t *In, int32_t *Out, size_t K) 90 { 91 ///////////////////////////////////////////////////////////// 92 // Filter operation: 93 // 94 // Perform resampling (4 input samples -> 3 output samples); 95 // process in sub blocks of size 4 samples. 96 size_t m; 97 int32_t tmp; 98 99 for (m = 0; m < K; m++) 100 { 101 tmp = 1 << 14; 102 tmp += kCoefficients32To24[0][0] * In[0]; 103 tmp += kCoefficients32To24[0][1] * In[1]; 104 tmp += kCoefficients32To24[0][2] * In[2]; 105 tmp += kCoefficients32To24[0][3] * In[3]; 106 tmp += kCoefficients32To24[0][4] * In[4]; 107 tmp += kCoefficients32To24[0][5] * In[5]; 108 tmp += kCoefficients32To24[0][6] * In[6]; 109 tmp += kCoefficients32To24[0][7] * In[7]; 110 Out[0] = tmp; 111 112 tmp = 1 << 14; 113 tmp += kCoefficients32To24[1][0] * In[1]; 114 tmp += kCoefficients32To24[1][1] * In[2]; 115 tmp += kCoefficients32To24[1][2] * In[3]; 116 tmp += kCoefficients32To24[1][3] * In[4]; 117 tmp += kCoefficients32To24[1][4] * In[5]; 118 tmp += kCoefficients32To24[1][5] * In[6]; 119 tmp += kCoefficients32To24[1][6] * In[7]; 120 tmp += kCoefficients32To24[1][7] * In[8]; 121 Out[1] = tmp; 122 123 tmp = 1 << 14; 124 tmp += kCoefficients32To24[2][0] * In[2]; 125 tmp += kCoefficients32To24[2][1] * In[3]; 126 tmp += kCoefficients32To24[2][2] * In[4]; 127 tmp += kCoefficients32To24[2][3] * In[5]; 128 tmp += kCoefficients32To24[2][4] * In[6]; 129 tmp += kCoefficients32To24[2][5] * In[7]; 130 tmp += kCoefficients32To24[2][6] * In[8]; 131 tmp += kCoefficients32To24[2][7] * In[9]; 132 Out[2] = tmp; 133 134 // update pointers 135 In += 4; 136 Out += 3; 137 } 138 } 139 140 // 141 // fractional resampling filters 142 // Fout = 11/16 * Fin 143 // Fout = 8/11 * Fin 144 // 145 146 // compute two inner-products and store them to output array 147 static void WebRtcSpl_ResampDotProduct(const int32_t *in1, const int32_t *in2, 148 const int16_t *coef_ptr, int32_t *out1, 149 int32_t *out2) 150 { 151 int32_t tmp1 = 16384; 152 int32_t tmp2 = 16384; 153 int16_t coef; 154 155 coef = coef_ptr[0]; 156 tmp1 += coef * in1[0]; 157 tmp2 += coef * in2[-0]; 158 159 coef = coef_ptr[1]; 160 tmp1 += coef * in1[1]; 161 tmp2 += coef * in2[-1]; 162 163 coef = coef_ptr[2]; 164 tmp1 += coef * in1[2]; 165 tmp2 += coef * in2[-2]; 166 167 coef = coef_ptr[3]; 168 tmp1 += coef * in1[3]; 169 tmp2 += coef * in2[-3]; 170 171 coef = coef_ptr[4]; 172 tmp1 += coef * in1[4]; 173 tmp2 += coef * in2[-4]; 174 175 coef = coef_ptr[5]; 176 tmp1 += coef * in1[5]; 177 tmp2 += coef * in2[-5]; 178 179 coef = coef_ptr[6]; 180 tmp1 += coef * in1[6]; 181 tmp2 += coef * in2[-6]; 182 183 coef = coef_ptr[7]; 184 tmp1 += coef * in1[7]; 185 tmp2 += coef * in2[-7]; 186 187 coef = coef_ptr[8]; 188 *out1 = tmp1 + coef * in1[8]; 189 *out2 = tmp2 + coef * in2[-8]; 190 } 191 192 // Resampling ratio: 8/11 193 // input: int32_t (normalized, not saturated) :: size 11 * K 194 // output: int32_t (shifted 15 positions to the left, + offset 16384) :: size 8 * K 195 // K: number of blocks 196 197 void WebRtcSpl_Resample44khzTo32khz(const int32_t *In, int32_t *Out, size_t K) 198 { 199 ///////////////////////////////////////////////////////////// 200 // Filter operation: 201 // 202 // Perform resampling (11 input samples -> 8 output samples); 203 // process in sub blocks of size 11 samples. 204 int32_t tmp; 205 size_t m; 206 207 for (m = 0; m < K; m++) 208 { 209 tmp = 1 << 14; 210 211 // first output sample 212 Out[0] = ((int32_t)In[3] << 15) + tmp; 213 214 // sum and accumulate filter coefficients and input samples 215 tmp += kCoefficients44To32[3][0] * In[5]; 216 tmp += kCoefficients44To32[3][1] * In[6]; 217 tmp += kCoefficients44To32[3][2] * In[7]; 218 tmp += kCoefficients44To32[3][3] * In[8]; 219 tmp += kCoefficients44To32[3][4] * In[9]; 220 tmp += kCoefficients44To32[3][5] * In[10]; 221 tmp += kCoefficients44To32[3][6] * In[11]; 222 tmp += kCoefficients44To32[3][7] * In[12]; 223 tmp += kCoefficients44To32[3][8] * In[13]; 224 Out[4] = tmp; 225 226 // sum and accumulate filter coefficients and input samples 227 WebRtcSpl_ResampDotProduct(&In[0], &In[17], kCoefficients44To32[0], &Out[1], &Out[7]); 228 229 // sum and accumulate filter coefficients and input samples 230 WebRtcSpl_ResampDotProduct(&In[2], &In[15], kCoefficients44To32[1], &Out[2], &Out[6]); 231 232 // sum and accumulate filter coefficients and input samples 233 WebRtcSpl_ResampDotProduct(&In[3], &In[14], kCoefficients44To32[2], &Out[3], &Out[5]); 234 235 // update pointers 236 In += 11; 237 Out += 8; 238 } 239 } 240
