1 /* Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
2 *
3 * Use of this source code is governed by a BSD-style license
4 * that can be found in the LICENSE file in the root of the source
5 * tree. An additional intellectual property rights grant can be found
6 * in the file PATENTS. All contributing project authors may
7 * be found in the AUTHORS file in the root of the source tree.
8 */
9
10 #include <stdint.h>
11
12 #include <memory>
13 #include <vector>
14
15 #include "absl/types/optional.h"
16 #include "api/array_view.h"
17 #include "modules/video_coding/jitter_estimator.h"
18 #include "rtc_base/experiments/jitter_upper_bound_experiment.h"
19 #include "rtc_base/numerics/histogram_percentile_counter.h"
20 #include "rtc_base/strings/string_builder.h"
21 #include "rtc_base/time_utils.h"
22 #include "system_wrappers/include/clock.h"
23 #include "test/field_trial.h"
24 #include "test/gtest.h"
25
26 namespace webrtc {
27
28 class TestVCMJitterEstimator : public ::testing::Test {
29 protected:
TestVCMJitterEstimator()30 TestVCMJitterEstimator() : fake_clock_(0) {}
31
SetUp()32 virtual void SetUp() {
33 estimator_ = std::make_unique<VCMJitterEstimator>(&fake_clock_);
34 }
35
AdvanceClock(int64_t microseconds)36 void AdvanceClock(int64_t microseconds) {
37 fake_clock_.AdvanceTimeMicroseconds(microseconds);
38 }
39
40 SimulatedClock fake_clock_;
41 std::unique_ptr<VCMJitterEstimator> estimator_;
42 };
43
44 // Generates some simple test data in the form of a sawtooth wave.
45 class ValueGenerator {
46 public:
ValueGenerator(int32_t amplitude)47 explicit ValueGenerator(int32_t amplitude)
48 : amplitude_(amplitude), counter_(0) {}
~ValueGenerator()49 virtual ~ValueGenerator() {}
50
Delay() const51 int64_t Delay() const { return ((counter_ % 11) - 5) * amplitude_; }
52
FrameSize() const53 uint32_t FrameSize() const { return 1000 + Delay(); }
54
Advance()55 void Advance() { ++counter_; }
56
57 private:
58 const int32_t amplitude_;
59 int64_t counter_;
60 };
61
62 // 5 fps, disable jitter delay altogether.
TEST_F(TestVCMJitterEstimator,TestLowRate)63 TEST_F(TestVCMJitterEstimator, TestLowRate) {
64 ValueGenerator gen(10);
65 uint64_t time_delta_us = rtc::kNumMicrosecsPerSec / 5;
66 for (int i = 0; i < 60; ++i) {
67 estimator_->UpdateEstimate(gen.Delay(), gen.FrameSize());
68 AdvanceClock(time_delta_us);
69 if (i > 2)
70 EXPECT_EQ(estimator_->GetJitterEstimate(0, absl::nullopt), 0);
71 gen.Advance();
72 }
73 }
74
TEST_F(TestVCMJitterEstimator,TestLowRateDisabled)75 TEST_F(TestVCMJitterEstimator, TestLowRateDisabled) {
76 test::ScopedFieldTrials field_trials(
77 "WebRTC-ReducedJitterDelayKillSwitch/Enabled/");
78 SetUp();
79
80 ValueGenerator gen(10);
81 uint64_t time_delta_us = rtc::kNumMicrosecsPerSec / 5;
82 for (int i = 0; i < 60; ++i) {
83 estimator_->UpdateEstimate(gen.Delay(), gen.FrameSize());
84 AdvanceClock(time_delta_us);
85 if (i > 2)
86 EXPECT_GT(estimator_->GetJitterEstimate(0, absl::nullopt), 0);
87 gen.Advance();
88 }
89 }
90
TEST_F(TestVCMJitterEstimator,TestUpperBound)91 TEST_F(TestVCMJitterEstimator, TestUpperBound) {
92 struct TestContext {
93 TestContext()
94 : upper_bound(0.0),
95 rtt_mult(0),
96 rtt_mult_add_cap_ms(absl::nullopt),
97 percentiles(1000) {}
98 double upper_bound;
99 double rtt_mult;
100 absl::optional<double> rtt_mult_add_cap_ms;
101 rtc::HistogramPercentileCounter percentiles;
102 };
103 std::vector<TestContext> test_cases(4);
104
105 // Large upper bound, rtt_mult = 0, and nullopt for rtt_mult addition cap.
106 test_cases[0].upper_bound = 100.0;
107 test_cases[0].rtt_mult = 0;
108 test_cases[0].rtt_mult_add_cap_ms = absl::nullopt;
109 // Small upper bound, rtt_mult = 0, and nullopt for rtt_mult addition cap.
110 test_cases[1].upper_bound = 3.5;
111 test_cases[1].rtt_mult = 0;
112 test_cases[1].rtt_mult_add_cap_ms = absl::nullopt;
113 // Large upper bound, rtt_mult = 1, and large rtt_mult addition cap value.
114 test_cases[2].upper_bound = 1000.0;
115 test_cases[2].rtt_mult = 1.0;
116 test_cases[2].rtt_mult_add_cap_ms = 200.0;
117 // Large upper bound, rtt_mult = 1, and small rtt_mult addition cap value.
118 test_cases[3].upper_bound = 1000.0;
119 test_cases[3].rtt_mult = 1.0;
120 test_cases[3].rtt_mult_add_cap_ms = 10.0;
121
122 // Test jitter buffer upper_bound and rtt_mult addition cap sizes.
123 for (TestContext& context : test_cases) {
124 // Set up field trial and reset jitter estimator.
125 char string_buf[64];
126 rtc::SimpleStringBuilder ssb(string_buf);
127 ssb << JitterUpperBoundExperiment::kJitterUpperBoundExperimentName
128 << "/Enabled-" << context.upper_bound << "/";
129 test::ScopedFieldTrials field_trials(ssb.str());
130 SetUp();
131
132 ValueGenerator gen(50);
133 uint64_t time_delta_us = rtc::kNumMicrosecsPerSec / 30;
134 constexpr int64_t kRttMs = 250;
135 for (int i = 0; i < 100; ++i) {
136 estimator_->UpdateEstimate(gen.Delay(), gen.FrameSize());
137 AdvanceClock(time_delta_us);
138 estimator_->FrameNacked(); // To test rtt_mult.
139 estimator_->UpdateRtt(kRttMs); // To test rtt_mult.
140 context.percentiles.Add(
141 static_cast<uint32_t>(estimator_->GetJitterEstimate(
142 context.rtt_mult, context.rtt_mult_add_cap_ms)));
143 gen.Advance();
144 }
145 }
146
147 // Median should be similar after three seconds. Allow 5% error margin.
148 uint32_t median_unbound = *test_cases[0].percentiles.GetPercentile(0.5);
149 uint32_t median_bounded = *test_cases[1].percentiles.GetPercentile(0.5);
150 EXPECT_NEAR(median_unbound, median_bounded, (median_unbound * 5) / 100);
151
152 // Max should be lower for the bounded case.
153 uint32_t max_unbound = *test_cases[0].percentiles.GetPercentile(1.0);
154 uint32_t max_bounded = *test_cases[1].percentiles.GetPercentile(1.0);
155 EXPECT_GT(max_unbound, static_cast<uint32_t>(max_bounded * 1.25));
156
157 // With rtt_mult = 1, max should be lower with small rtt_mult add cap value.
158 max_unbound = *test_cases[2].percentiles.GetPercentile(1.0);
159 max_bounded = *test_cases[3].percentiles.GetPercentile(1.0);
160 EXPECT_GT(max_unbound, static_cast<uint32_t>(max_bounded * 1.25));
161 }
162
163 } // namespace webrtc
164