1 /*
2 * Copyright (C) 2021 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <iostream>
18 #include <vector>
19
20 constexpr int kMinLoopLimitValue = 1;
21 constexpr int kNumPeaks = 3;
22
23 /*!
24 \brief Compute the length normalized correlation of two signals
25
26 \sigX Pointer to signal 1
27 \sigY Pointer to signal 2
28 \len Length of signals
29 \enableCrossCorr Flag to be set to 1 if cross-correlation is needed
30
31 \return First value is vector of correlation peak indices
32 Second value is vector of correlation peak values
33 */
34
correlation(const int16_t * sigX,const int16_t * sigY,int len,int16_t enableCrossCorr)35 static std::pair<std::vector<int>, std::vector<float>> correlation(const int16_t* sigX,
36 const int16_t* sigY, int len,
37 int16_t enableCrossCorr) {
38 float maxCorrVal = 0.f, prevCorrVal = 0.f;
39 int delay = 0, peakIndex = 0, flag = 0;
40 int loopLim = (1 == enableCrossCorr) ? len : kMinLoopLimitValue;
41 std::vector<int> peakIndexVect(kNumPeaks, 0);
42 std::vector<float> peakValueVect(kNumPeaks, 0.f);
43 for (int i = 0; i < loopLim; i++) {
44 float corrVal = 0.f;
45 for (int j = i; j < len; j++) {
46 corrVal += (float)(sigX[j] * sigY[j - i]);
47 }
48 corrVal /= len - i;
49 if (corrVal > maxCorrVal) {
50 delay = i;
51 maxCorrVal = corrVal;
52 }
53 // Correlation peaks are expected to be observed at equal intervals. The interval length is
54 // expected to match with wave period.
55 // The following block of code saves the first kNumPeaks number of peaks and the index at
56 // which they occur.
57 if (peakIndex < kNumPeaks) {
58 if (corrVal > prevCorrVal) {
59 peakIndexVect[peakIndex] = i;
60 peakValueVect[peakIndex] = corrVal;
61 flag = 0;
62 } else if (0 == flag) {
63 peakIndex++;
64 flag = 1;
65 }
66 }
67 if (peakIndex == kNumPeaks) break;
68 prevCorrVal = corrVal;
69 }
70 return {peakIndexVect, peakValueVect};
71 }
72
printUsage()73 void printUsage() {
74 printf("\nUsage: ");
75 printf("\n correlation <firstFile> <secondFile> [enableCrossCorr]\n");
76 printf("\nwhere, \n <firstFile> is the first file name");
77 printf("\n <secondFile> is the second file name");
78 printf("\n [enableCrossCorr] is flag to set for cross-correlation (Default 1)\n\n");
79 }
80
main(int argc,const char * argv[])81 int main(int argc, const char* argv[]) {
82 if (argc < 3) {
83 printUsage();
84 return EXIT_FAILURE;
85 }
86
87 std::unique_ptr<FILE, decltype(&fclose)> fInput1(fopen(argv[1], "rb"), &fclose);
88 if (fInput1.get() == NULL) {
89 printf("\nError: missing file %s\n", argv[1]);
90 return EXIT_FAILURE;
91 }
92 std::unique_ptr<FILE, decltype(&fclose)> fInput2(fopen(argv[2], "rb"), &fclose);
93 if (fInput2.get() == NULL) {
94 printf("\nError: missing file %s\n", argv[2]);
95 return EXIT_FAILURE;
96 }
97 int16_t enableCrossCorr = (4 == argc) ? atoi(argv[3]) : 1;
98
99 fseek(fInput1.get(), 0L, SEEK_END);
100 unsigned int fileSize1 = ftell(fInput1.get());
101 rewind(fInput1.get());
102 fseek(fInput2.get(), 0L, SEEK_END);
103 unsigned int fileSize2 = ftell(fInput2.get());
104 rewind(fInput2.get());
105 if (fileSize1 != fileSize2) {
106 printf("\nError: File sizes different\n");
107 return EXIT_FAILURE;
108 }
109
110 size_t numFrames = fileSize1 / sizeof(int16_t);
111 std::unique_ptr<int16_t[]> inBuffer1(new int16_t[numFrames]());
112 std::unique_ptr<int16_t[]> inBuffer2(new int16_t[numFrames]());
113
114 if (numFrames != fread(inBuffer1.get(), sizeof(int16_t), numFrames, fInput1.get())) {
115 printf("\nError: Unable to read %zu samples from file %s\n", numFrames, argv[1]);
116 return EXIT_FAILURE;
117 }
118
119 if (numFrames != fread(inBuffer2.get(), sizeof(int16_t), numFrames, fInput2.get())) {
120 printf("\nError: Unable to read %zu samples from file %s\n", numFrames, argv[2]);
121 return EXIT_FAILURE;
122 }
123
124 auto pairAutoCorr1 = correlation(inBuffer1.get(), inBuffer1.get(), numFrames, enableCrossCorr);
125 auto pairAutoCorr2 = correlation(inBuffer2.get(), inBuffer2.get(), numFrames, enableCrossCorr);
126
127 // Following code block checks pitch period difference between two input signals. They must
128 // match as AGC applies only gain, no frequency related computation is done.
129 bool pitchMatch = false;
130 for (unsigned i = 0; i < pairAutoCorr1.first.size() - 1; i++) {
131 if (pairAutoCorr1.first[i + 1] - pairAutoCorr1.first[i] !=
132 pairAutoCorr2.first[i + 1] - pairAutoCorr2.first[i]) {
133 pitchMatch = false;
134 break;
135 }
136 pitchMatch = true;
137 }
138 if (pitchMatch) {
139 printf("Auto-correlation : Pitch matched\n");
140 } else {
141 printf("Auto-correlation : Pitch mismatch\n");
142 return EXIT_FAILURE;
143 }
144
145 if (enableCrossCorr) {
146 auto pairCrossCorr =
147 correlation(inBuffer1.get(), inBuffer2.get(), numFrames, enableCrossCorr);
148
149 // Since AGC applies only gain, the pitch information obtained from cross correlation data
150 // of input and output is expected to be same as the input signal's pitch information.
151 pitchMatch = false;
152 for (unsigned i = 0; i < pairCrossCorr.first.size() - 1; i++) {
153 if (pairAutoCorr1.first[i + 1] - pairAutoCorr1.first[i] !=
154 pairCrossCorr.first[i + 1] - pairCrossCorr.first[i]) {
155 pitchMatch = false;
156 break;
157 }
158 pitchMatch = true;
159 }
160 if (pitchMatch) {
161 printf("Cross-correlation : Pitch matched for AGC\n");
162 if (pairAutoCorr1.second[0]) {
163 printf("Expected gain : (maxCrossCorr / maxAutoCorr1) = %f\n",
164 pairCrossCorr.second[0] / pairAutoCorr1.second[0]);
165 }
166 } else {
167 printf("Cross-correlation : Pitch mismatch\n");
168 return EXIT_FAILURE;
169 }
170 }
171
172 return EXIT_SUCCESS;
173 }
174