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      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 
     20 VCMCodecTimer::VCMCodecTimer()
     21     : _filteredMax(0), _ignoredSampleCount(0), _shortMax(0), _history() {
     22   Reset();
     23 }
     24 
     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
     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 
     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 
     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
     93 int32_t VCMCodecTimer::RequiredDecodeTimeMs(FrameType /*frameType*/) const {
     94   return _filteredMax;
     95 }
     96 }  // namespace webrtc
     97