1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "media/base/multi_channel_resampler.h"
6
7 #include <cmath>
8 #include <memory>
9
10 #include "base/bind.h"
11 #include "base/bind_helpers.h"
12 #include "base/logging.h"
13 #include "base/macros.h"
14 #include "media/base/audio_bus.h"
15 #include "testing/gtest/include/gtest/gtest.h"
16
17 namespace media {
18
19 // Just test a basic resampling case. The SincResampler unit test will take
20 // care of accuracy testing; we just need to check that multichannel works as
21 // expected within some tolerance.
22 static const float kScaleFactor = 192000.0f / 44100.0f;
23
24 // Simulate large and small sample requests used by the different audio paths.
25 static const int kHighLatencySize = 8192;
26 // Low latency buffers show a larger error than high latency ones. Which makes
27 // sense since each error represents a larger portion of the total request.
28 static const int kLowLatencySize = 128;
29
30 // Test fill value.
31 static const float kFillValue = 0.1f;
32
33 // Chosen arbitrarily based on what each resampler reported during testing.
34 static const double kLowLatencyMaxRMSError = 0.0036;
35 static const double kLowLatencyMaxError = 0.04;
36 static const double kHighLatencyMaxRMSError = 0.0036;
37 static const double kHighLatencyMaxError = 0.04;
38
39 class MultiChannelResamplerTest
40 : public testing::TestWithParam<int> {
41 public:
MultiChannelResamplerTest()42 MultiChannelResamplerTest()
43 : last_frame_delay_(-1) {
44 }
45 virtual ~MultiChannelResamplerTest() = default;
46
InitializeAudioData(int channels,int frames)47 void InitializeAudioData(int channels, int frames) {
48 frames_ = frames;
49 audio_bus_ = AudioBus::Create(channels, frames);
50 }
51
52 // MultiChannelResampler::MultiChannelAudioSourceProvider implementation, just
53 // fills the provided audio_data with |kFillValue|.
ProvideInput(int frame_delay,AudioBus * audio_bus)54 virtual void ProvideInput(int frame_delay, AudioBus* audio_bus) {
55 EXPECT_GE(frame_delay, last_frame_delay_);
56 last_frame_delay_ = frame_delay;
57
58 float fill_value = fill_junk_values_ ? (1 / kFillValue) : kFillValue;
59 EXPECT_EQ(audio_bus->channels(), audio_bus_->channels());
60 for (int i = 0; i < audio_bus->channels(); ++i)
61 for (int j = 0; j < audio_bus->frames(); ++j)
62 audio_bus->channel(i)[j] = fill_value;
63 }
64
MultiChannelTest(int channels,int frames,double expected_max_rms_error,double expected_max_error)65 void MultiChannelTest(int channels, int frames, double expected_max_rms_error,
66 double expected_max_error) {
67 InitializeAudioData(channels, frames);
68 MultiChannelResampler resampler(
69 channels, kScaleFactor, SincResampler::kDefaultRequestSize,
70 base::BindRepeating(&MultiChannelResamplerTest::ProvideInput,
71 base::Unretained(this)));
72
73 // First prime the resampler with some junk data, so we can verify Flush().
74 fill_junk_values_ = true;
75 resampler.Resample(1, audio_bus_.get());
76 resampler.Flush();
77 fill_junk_values_ = false;
78
79 // The last frame delay should be strictly less than the total frame count.
80 EXPECT_LT(last_frame_delay_, audio_bus_->frames());
81 last_frame_delay_ = -1;
82
83 // If Flush() didn't work, the rest of the tests will fail.
84 resampler.Resample(frames, audio_bus_.get());
85 TestValues(expected_max_rms_error, expected_max_error);
86 }
87
HighLatencyTest(int channels)88 void HighLatencyTest(int channels) {
89 MultiChannelTest(channels, kHighLatencySize, kHighLatencyMaxRMSError,
90 kHighLatencyMaxError);
91 }
92
LowLatencyTest(int channels)93 void LowLatencyTest(int channels) {
94 MultiChannelTest(channels, kLowLatencySize, kLowLatencyMaxRMSError,
95 kLowLatencyMaxError);
96 }
97
TestValues(double expected_max_rms_error,double expected_max_error)98 void TestValues(double expected_max_rms_error, double expected_max_error ) {
99 // Calculate Root-Mean-Square-Error for the resampling.
100 double max_error = 0.0;
101 double sum_of_squares = 0.0;
102 for (int i = 0; i < audio_bus_->channels(); ++i) {
103 for (int j = 0; j < frames_; ++j) {
104 // Ensure all values are accounted for.
105 ASSERT_NE(audio_bus_->channel(i)[j], 0);
106
107 double error = fabs(audio_bus_->channel(i)[j] - kFillValue);
108 max_error = std::max(max_error, error);
109 sum_of_squares += error * error;
110 }
111 }
112
113 double rms_error = sqrt(
114 sum_of_squares / (frames_ * audio_bus_->channels()));
115
116 EXPECT_LE(rms_error, expected_max_rms_error);
117 EXPECT_LE(max_error, expected_max_error);
118 }
119
120 protected:
121 int frames_;
122 bool fill_junk_values_;
123 std::unique_ptr<AudioBus> audio_bus_;
124 int last_frame_delay_;
125
126 DISALLOW_COPY_AND_ASSIGN(MultiChannelResamplerTest);
127 };
128
TEST_P(MultiChannelResamplerTest,HighLatency)129 TEST_P(MultiChannelResamplerTest, HighLatency) {
130 HighLatencyTest(GetParam());
131 }
132
TEST_P(MultiChannelResamplerTest,LowLatency)133 TEST_P(MultiChannelResamplerTest, LowLatency) {
134 LowLatencyTest(GetParam());
135 }
136
137 // Test common channel layouts: mono, stereo, 5.1, 7.1.
138 INSTANTIATE_TEST_SUITE_P(MultiChannelResamplerTest,
139 MultiChannelResamplerTest,
140 testing::Values(1, 2, 6, 8));
141
142 } // namespace media
143