1 /*
2 * Copyright (c) 2012 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 #include "modules/remote_bitrate_estimator/overuse_detector.h"
12
13 #include <math.h>
14 #include <stdio.h>
15
16 #include <algorithm>
17 #include <string>
18
19 #include "modules/remote_bitrate_estimator/test/bwe_test_logging.h"
20 #include "rtc_base/checks.h"
21 #include "rtc_base/numerics/safe_minmax.h"
22
23 namespace webrtc {
24
25 const double kMaxAdaptOffsetMs = 15.0;
26 const double kOverUsingTimeThreshold = 10;
27 const int kMaxNumDeltas = 60;
28
OveruseDetector(const FieldTrialsView * key_value_config)29 OveruseDetector::OveruseDetector(const FieldTrialsView* key_value_config)
30 // Experiment is on by default, but can be disabled with finch by setting
31 // the field trial string to "WebRTC-AdaptiveBweThreshold/Disabled/".
32 : k_up_(0.0087),
33 k_down_(0.039),
34 overusing_time_threshold_(kOverUsingTimeThreshold),
35 threshold_(12.5),
36 last_update_ms_(-1),
37 prev_offset_(0.0),
38 time_over_using_(-1),
39 overuse_counter_(0),
40 hypothesis_(BandwidthUsage::kBwNormal) {}
41
~OveruseDetector()42 OveruseDetector::~OveruseDetector() {}
43
State() const44 BandwidthUsage OveruseDetector::State() const {
45 return hypothesis_;
46 }
47
Detect(double offset,double ts_delta,int num_of_deltas,int64_t now_ms)48 BandwidthUsage OveruseDetector::Detect(double offset,
49 double ts_delta,
50 int num_of_deltas,
51 int64_t now_ms) {
52 if (num_of_deltas < 2) {
53 return BandwidthUsage::kBwNormal;
54 }
55 const double T = std::min(num_of_deltas, kMaxNumDeltas) * offset;
56 BWE_TEST_LOGGING_PLOT(1, "T", now_ms, T);
57 BWE_TEST_LOGGING_PLOT(1, "threshold", now_ms, threshold_);
58 if (T > threshold_) {
59 if (time_over_using_ == -1) {
60 // Initialize the timer. Assume that we've been
61 // over-using half of the time since the previous
62 // sample.
63 time_over_using_ = ts_delta / 2;
64 } else {
65 // Increment timer
66 time_over_using_ += ts_delta;
67 }
68 overuse_counter_++;
69 if (time_over_using_ > overusing_time_threshold_ && overuse_counter_ > 1) {
70 if (offset >= prev_offset_) {
71 time_over_using_ = 0;
72 overuse_counter_ = 0;
73 hypothesis_ = BandwidthUsage::kBwOverusing;
74 }
75 }
76 } else if (T < -threshold_) {
77 time_over_using_ = -1;
78 overuse_counter_ = 0;
79 hypothesis_ = BandwidthUsage::kBwUnderusing;
80 } else {
81 time_over_using_ = -1;
82 overuse_counter_ = 0;
83 hypothesis_ = BandwidthUsage::kBwNormal;
84 }
85 prev_offset_ = offset;
86
87 UpdateThreshold(T, now_ms);
88
89 return hypothesis_;
90 }
91
UpdateThreshold(double modified_offset,int64_t now_ms)92 void OveruseDetector::UpdateThreshold(double modified_offset, int64_t now_ms) {
93 if (last_update_ms_ == -1)
94 last_update_ms_ = now_ms;
95
96 if (fabs(modified_offset) > threshold_ + kMaxAdaptOffsetMs) {
97 // Avoid adapting the threshold to big latency spikes, caused e.g.,
98 // by a sudden capacity drop.
99 last_update_ms_ = now_ms;
100 return;
101 }
102
103 const double k = fabs(modified_offset) < threshold_ ? k_down_ : k_up_;
104 const int64_t kMaxTimeDeltaMs = 100;
105 int64_t time_delta_ms = std::min(now_ms - last_update_ms_, kMaxTimeDeltaMs);
106 threshold_ += k * (fabs(modified_offset) - threshold_) * time_delta_ms;
107 threshold_ = rtc::SafeClamp(threshold_, 6.f, 600.f);
108 last_update_ms_ = now_ms;
109 }
110
111 } // namespace webrtc
112