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
WebRtcSpl_Resample48khzTo32khz(const int32_t * In,int32_t * Out,size_t K)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
WebRtcSpl_Resample32khzTo24khz(const int32_t * In,int32_t * Out,size_t K)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
WebRtcSpl_ResampDotProduct(const int32_t * in1,const int32_t * in2,const int16_t * coef_ptr,int32_t * out1,int32_t * out2)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
WebRtcSpl_Resample44khzTo32khz(const int32_t * In,int32_t * Out,size_t K)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