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 "webrtc/modules/audio_coding/neteq/delay_peak_detector.h"
12
13 #include <algorithm> // max
14
15 namespace webrtc {
16
17 // The DelayPeakDetector keeps track of severe inter-arrival times, called
18 // delay peaks. When a peak is observed, the "height" (the time elapsed since
19 // the previous packet arrival) and the peak "period" (the time since the last
20 // observed peak) is recorded in a vector. When enough peaks have been observed,
21 // peak-mode is engaged and the DelayManager asks the DelayPeakDetector for
22 // the worst peak height.
23
24 DelayPeakDetector::~DelayPeakDetector() = default;
25
DelayPeakDetector()26 DelayPeakDetector::DelayPeakDetector()
27 : peak_found_(false),
28 peak_detection_threshold_(0),
29 peak_period_counter_ms_(-1) {
30 }
31
Reset()32 void DelayPeakDetector::Reset() {
33 peak_period_counter_ms_ = -1; // Indicate that next peak is the first.
34 peak_found_ = false;
35 peak_history_.clear();
36 }
37
38 // Calculates the threshold in number of packets.
SetPacketAudioLength(int length_ms)39 void DelayPeakDetector::SetPacketAudioLength(int length_ms) {
40 if (length_ms > 0) {
41 peak_detection_threshold_ = kPeakHeightMs / length_ms;
42 }
43 }
44
peak_found()45 bool DelayPeakDetector::peak_found() {
46 return peak_found_;
47 }
48
MaxPeakHeight() const49 int DelayPeakDetector::MaxPeakHeight() const {
50 int max_height = -1; // Returns -1 for an empty history.
51 std::list<Peak>::const_iterator it;
52 for (it = peak_history_.begin(); it != peak_history_.end(); ++it) {
53 max_height = std::max(max_height, it->peak_height_packets);
54 }
55 return max_height;
56 }
57
MaxPeakPeriod() const58 int DelayPeakDetector::MaxPeakPeriod() const {
59 int max_period = -1; // Returns -1 for an empty history.
60 std::list<Peak>::const_iterator it;
61 for (it = peak_history_.begin(); it != peak_history_.end(); ++it) {
62 max_period = std::max(max_period, it->period_ms);
63 }
64 return max_period;
65 }
66
Update(int inter_arrival_time,int target_level)67 bool DelayPeakDetector::Update(int inter_arrival_time, int target_level) {
68 if (inter_arrival_time > target_level + peak_detection_threshold_ ||
69 inter_arrival_time > 2 * target_level) {
70 // A delay peak is observed.
71 if (peak_period_counter_ms_ == -1) {
72 // This is the first peak. Reset the period counter.
73 peak_period_counter_ms_ = 0;
74 } else if (peak_period_counter_ms_ <= kMaxPeakPeriodMs) {
75 // This is not the first peak, and the period is valid.
76 // Store peak data in the vector.
77 Peak peak_data;
78 peak_data.period_ms = peak_period_counter_ms_;
79 peak_data.peak_height_packets = inter_arrival_time;
80 peak_history_.push_back(peak_data);
81 while (peak_history_.size() > kMaxNumPeaks) {
82 // Delete the oldest data point.
83 peak_history_.pop_front();
84 }
85 peak_period_counter_ms_ = 0;
86 } else if (peak_period_counter_ms_ <= 2 * kMaxPeakPeriodMs) {
87 // Invalid peak due to too long period. Reset period counter and start
88 // looking for next peak.
89 peak_period_counter_ms_ = 0;
90 } else {
91 // More than 2 times the maximum period has elapsed since the last peak
92 // was registered. It seams that the network conditions have changed.
93 // Reset the peak statistics.
94 Reset();
95 }
96 }
97 return CheckPeakConditions();
98 }
99
IncrementCounter(int inc_ms)100 void DelayPeakDetector::IncrementCounter(int inc_ms) {
101 if (peak_period_counter_ms_ >= 0) {
102 peak_period_counter_ms_ += inc_ms;
103 }
104 }
105
CheckPeakConditions()106 bool DelayPeakDetector::CheckPeakConditions() {
107 size_t s = peak_history_.size();
108 if (s >= kMinPeaksToTrigger &&
109 peak_period_counter_ms_ <= 2 * MaxPeakPeriod()) {
110 peak_found_ = true;
111 } else {
112 peak_found_ = false;
113 }
114 return peak_found_;
115 }
116 } // namespace webrtc
117