1 /*
2 * Copyright 2022 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 /*
18 * Test FlowGraph
19 *
20 * This file also tests a few different conversion techniques because
21 * sometimes that have caused compiler bugs.
22 */
23
24 #include <iostream>
25
26 #include <gtest/gtest.h>
27
28 #include "flowgraph/resampler/MultiChannelResampler.h"
29
30 using namespace RESAMPLER_OUTER_NAMESPACE::resampler;
31
32 // Measure zero crossings.
countZeroCrossingsWithHysteresis(float * input,int32_t numSamples)33 static int32_t countZeroCrossingsWithHysteresis(float *input, int32_t numSamples) {
34 const float kHysteresisLevel = 0.25f;
35 int zeroCrossingCount = 0;
36 int state = 0; // can be -1, 0, +1
37 for (int i = 0; i < numSamples; i++) {
38 if (input[i] >= kHysteresisLevel) {
39 if (state < 0) {
40 zeroCrossingCount++;
41 }
42 state = 1;
43 } else if (input[i] <= -kHysteresisLevel) {
44 if (state > 0) {
45 zeroCrossingCount++;
46 }
47 state = -1;
48 }
49 }
50 return zeroCrossingCount;
51 }
52
53 static constexpr int kChannelCount = 1;
54
55 /**
56 * Convert a sine wave and then look for glitches.
57 * Glitches have a high value in the second derivative.
58 */
checkResampler(int32_t sourceRate,int32_t sinkRate,MultiChannelResampler::Quality quality)59 static void checkResampler(int32_t sourceRate, int32_t sinkRate,
60 MultiChannelResampler::Quality quality) {
61 const int kNumOutputSamples = 10000;
62 const double framesPerCycle = 81.379; // target output period
63
64 int numInputSamples = kNumOutputSamples * sourceRate / sinkRate;
65
66 std::unique_ptr<float[]> inputBuffer = std::make_unique<float[]>(numInputSamples);
67 std::unique_ptr<float[]> outputBuffer = std::make_unique<float[]>(kNumOutputSamples);
68
69 // Generate a sine wave for input.
70 const double kPhaseIncrement = 2.0 * sinkRate / (framesPerCycle * sourceRate);
71 double phase = 0.0;
72 for (int i = 0; i < numInputSamples; i++) {
73 inputBuffer[i] = sin(phase * M_PI);
74 phase += kPhaseIncrement;
75 while (phase > 1.0) {
76 phase -= 2.0;
77 }
78 }
79 int sourceZeroCrossingCount = countZeroCrossingsWithHysteresis(
80 inputBuffer.get(), numInputSamples);
81
82 // Use a MultiChannelResampler to convert from the sourceRate to the sinkRate.
83 std::unique_ptr<MultiChannelResampler> mcResampler;
84 mcResampler.reset(MultiChannelResampler::make(kChannelCount,
85 sourceRate,
86 sinkRate,
87 quality));
88 int inputFramesLeft = numInputSamples;
89 int numRead = 0;
90 float *input = inputBuffer.get(); // for iteration
91 float *output = outputBuffer.get();
92 while (inputFramesLeft > 0) {
93 if (mcResampler->isWriteNeeded()) {
94 mcResampler->writeNextFrame(input);
95 input++;
96 inputFramesLeft--;
97 } else {
98 mcResampler->readNextFrame(output);
99 output++;
100 numRead++;
101 }
102 }
103
104 // Flush out remaining frames from the flowgraph
105 while (!mcResampler->isWriteNeeded()) {
106 mcResampler->readNextFrame(output);
107 output++;
108 numRead++;
109 }
110
111 ASSERT_LE(numRead, kNumOutputSamples);
112 // Some frames are lost priming the FIR filter.
113 const int kMaxAlgorithmicFrameLoss = 5;
114 EXPECT_GT(numRead, kNumOutputSamples - kMaxAlgorithmicFrameLoss);
115
116 int sinkZeroCrossingCount = countZeroCrossingsWithHysteresis(outputBuffer.get(), numRead);
117 const int kMaxZeroCrossingDelta = std::max(sinkRate / sourceRate / 2, 1);
118 EXPECT_LE(abs(sourceZeroCrossingCount - sinkZeroCrossingCount), kMaxZeroCrossingDelta);
119
120 // Detect glitches by looking for spikes in the second derivative.
121 output = outputBuffer.get();
122 float previousValue = output[0];
123 float previousSlope = output[1] - output[0];
124 for (int i = 0; i < numRead; i++) {
125 float slope = output[i] - previousValue;
126 float slopeDelta = fabs(slope - previousSlope);
127 // Skip a few samples because there are often some steep slope changes at the beginning.
128 if (i > 10) {
129 EXPECT_LT(slopeDelta, 0.1);
130 }
131 previousValue = output[i];
132 previousSlope = slope;
133 }
134
135 #if 0
136 // Save to disk for inspection.
137 FILE *fp = fopen( "/sdcard/Download/src_float_out.raw" , "wb" );
138 fwrite(outputBuffer.get(), sizeof(float), numRead, fp );
139 fclose(fp);
140 #endif
141 }
142
143
TEST(test_resampler,resampler_scan_all)144 TEST(test_resampler, resampler_scan_all) {
145 const int rates[] = {8000, 11025, 22050, 32000, 44100, 48000, 64000, 88200, 96000};
146 const MultiChannelResampler::Quality qualities[] =
147 {
148 MultiChannelResampler::Quality::Fastest,
149 MultiChannelResampler::Quality::Low,
150 MultiChannelResampler::Quality::Medium,
151 MultiChannelResampler::Quality::High,
152 MultiChannelResampler::Quality::Best
153 };
154 for (int srcRate : rates) {
155 for (int destRate : rates) {
156 for (auto quality : qualities) {
157 if (srcRate != destRate) {
158 checkResampler(srcRate, destRate, quality);
159 }
160 }
161 }
162 }
163 }
164
TEST(test_resampler,resampler_8000_11025_best)165 TEST(test_resampler, resampler_8000_11025_best) {
166 checkResampler(8000, 11025, MultiChannelResampler::Quality::Best);
167 }
TEST(test_resampler,resampler_8000_48000_best)168 TEST(test_resampler, resampler_8000_48000_best) {
169 checkResampler(8000, 48000, MultiChannelResampler::Quality::Best);
170 }
171
TEST(test_resampler,resampler_8000_44100_best)172 TEST(test_resampler, resampler_8000_44100_best) {
173 checkResampler(8000, 44100, MultiChannelResampler::Quality::Best);
174 }
175
TEST(test_resampler,resampler_11025_24000_best)176 TEST(test_resampler, resampler_11025_24000_best) {
177 checkResampler(11025, 24000, MultiChannelResampler::Quality::Best);
178 }
179
TEST(test_resampler,resampler_11025_48000_fastest)180 TEST(test_resampler, resampler_11025_48000_fastest) {
181 checkResampler(11025, 48000, MultiChannelResampler::Quality::Fastest);
182 }
TEST(test_resampler,resampler_11025_48000_low)183 TEST(test_resampler, resampler_11025_48000_low) {
184 checkResampler(11025, 48000, MultiChannelResampler::Quality::Low);
185 }
TEST(test_resampler,resampler_11025_48000_medium)186 TEST(test_resampler, resampler_11025_48000_medium) {
187 checkResampler(11025, 48000, MultiChannelResampler::Quality::Medium);
188 }
TEST(test_resampler,resampler_11025_48000_high)189 TEST(test_resampler, resampler_11025_48000_high) {
190 checkResampler(11025, 48000, MultiChannelResampler::Quality::High);
191 }
192
TEST(test_resampler,resampler_11025_48000_best)193 TEST(test_resampler, resampler_11025_48000_best) {
194 checkResampler(11025, 48000, MultiChannelResampler::Quality::Best);
195 }
196
TEST(test_resampler,resampler_11025_44100_best)197 TEST(test_resampler, resampler_11025_44100_best) {
198 checkResampler(11025, 44100, MultiChannelResampler::Quality::Best);
199 }
200
TEST(test_resampler,resampler_11025_88200_best)201 TEST(test_resampler, resampler_11025_88200_best) {
202 checkResampler(11025, 88200, MultiChannelResampler::Quality::Best);
203 }
204
TEST(test_resampler,resampler_16000_48000_best)205 TEST(test_resampler, resampler_16000_48000_best) {
206 checkResampler(16000, 48000, MultiChannelResampler::Quality::Best);
207 }
208
TEST(test_resampler,resampler_44100_48000_low)209 TEST(test_resampler, resampler_44100_48000_low) {
210 checkResampler(44100, 48000, MultiChannelResampler::Quality::Low);
211 }
TEST(test_resampler,resampler_44100_48000_best)212 TEST(test_resampler, resampler_44100_48000_best) {
213 checkResampler(44100, 48000, MultiChannelResampler::Quality::Best);
214 }
215
216 // Look for glitches when downsampling.
TEST(test_resampler,resampler_48000_11025_best)217 TEST(test_resampler, resampler_48000_11025_best) {
218 checkResampler(48000, 11025, MultiChannelResampler::Quality::Best);
219 }
TEST(test_resampler,resampler_48000_44100_best)220 TEST(test_resampler, resampler_48000_44100_best) {
221 checkResampler(48000, 44100, MultiChannelResampler::Quality::Best);
222 }
TEST(test_resampler,resampler_44100_11025_best)223 TEST(test_resampler, resampler_44100_11025_best) {
224 checkResampler(44100, 11025, MultiChannelResampler::Quality::Best);
225 }
226