1 /*
2  *  Copyright (c) 2011 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/video_coding/codec_timer.h"
12 
13 #include <assert.h>
14 
15 namespace webrtc {
16 
17 // The first kIgnoredSampleCount samples will be ignored.
18 static const int32_t kIgnoredSampleCount = 5;
19 
VCMCodecTimer()20 VCMCodecTimer::VCMCodecTimer()
21     : _filteredMax(0), _ignoredSampleCount(0), _shortMax(0), _history() {
22   Reset();
23 }
24 
Reset()25 void VCMCodecTimer::Reset() {
26   _filteredMax = 0;
27   _ignoredSampleCount = 0;
28   _shortMax = 0;
29   for (int i = 0; i < MAX_HISTORY_SIZE; i++) {
30     _history[i].shortMax = 0;
31     _history[i].timeMs = -1;
32   }
33 }
34 
35 // Update the max-value filter
MaxFilter(int32_t decodeTime,int64_t nowMs)36 void VCMCodecTimer::MaxFilter(int32_t decodeTime, int64_t nowMs) {
37   if (_ignoredSampleCount >= kIgnoredSampleCount) {
38     UpdateMaxHistory(decodeTime, nowMs);
39     ProcessHistory(nowMs);
40   } else {
41     _ignoredSampleCount++;
42   }
43 }
44 
UpdateMaxHistory(int32_t decodeTime,int64_t now)45 void VCMCodecTimer::UpdateMaxHistory(int32_t decodeTime, int64_t now) {
46   if (_history[0].timeMs >= 0 && now - _history[0].timeMs < SHORT_FILTER_MS) {
47     if (decodeTime > _shortMax) {
48       _shortMax = decodeTime;
49     }
50   } else {
51     // Only add a new value to the history once a second
52     if (_history[0].timeMs == -1) {
53       // First, no shift
54       _shortMax = decodeTime;
55     } else {
56       // Shift
57       for (int i = (MAX_HISTORY_SIZE - 2); i >= 0; i--) {
58         _history[i + 1].shortMax = _history[i].shortMax;
59         _history[i + 1].timeMs = _history[i].timeMs;
60       }
61     }
62     if (_shortMax == 0) {
63       _shortMax = decodeTime;
64     }
65 
66     _history[0].shortMax = _shortMax;
67     _history[0].timeMs = now;
68     _shortMax = 0;
69   }
70 }
71 
ProcessHistory(int64_t nowMs)72 void VCMCodecTimer::ProcessHistory(int64_t nowMs) {
73   _filteredMax = _shortMax;
74   if (_history[0].timeMs == -1) {
75     return;
76   }
77   for (int i = 0; i < MAX_HISTORY_SIZE; i++) {
78     if (_history[i].timeMs == -1) {
79       break;
80     }
81     if (nowMs - _history[i].timeMs > MAX_HISTORY_SIZE * SHORT_FILTER_MS) {
82       // This sample (and all samples after this) is too old
83       break;
84     }
85     if (_history[i].shortMax > _filteredMax) {
86       // This sample is the largest one this far into the history
87       _filteredMax = _history[i].shortMax;
88     }
89   }
90 }
91 
92 // Get the maximum observed time within a time window
RequiredDecodeTimeMs(FrameType) const93 int32_t VCMCodecTimer::RequiredDecodeTimeMs(FrameType /*frameType*/) const {
94   return _filteredMax;
95 }
96 }  // namespace webrtc
97