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_processing/main/interface/video_processing.h"
12#include "webrtc/modules/video_processing/main/source/video_decimator.h"
13#include "webrtc/system_wrappers/interface/tick_util.h"
14
15#define VD_MIN(a, b) ((a) < (b)) ? (a) : (b)
16
17namespace webrtc {
18
19VPMVideoDecimator::VPMVideoDecimator() {
20  Reset();
21}
22
23VPMVideoDecimator::~VPMVideoDecimator() {}
24
25void VPMVideoDecimator::Reset()  {
26  overshoot_modifier_ = 0;
27  drop_count_ = 0;
28  keep_count_ = 0;
29  target_frame_rate_ = 30;
30  incoming_frame_rate_ = 0.0f;
31  memset(incoming_frame_times_, 0, sizeof(incoming_frame_times_));
32  enable_temporal_decimation_ = true;
33}
34
35void VPMVideoDecimator::EnableTemporalDecimation(bool enable) {
36  enable_temporal_decimation_ = enable;
37}
38
39int32_t VPMVideoDecimator::SetTargetFramerate(uint32_t frame_rate) {
40  if (frame_rate == 0) return VPM_PARAMETER_ERROR;
41
42  target_frame_rate_ = frame_rate;
43  return VPM_OK;
44}
45
46bool VPMVideoDecimator::DropFrame() {
47  if (!enable_temporal_decimation_) return false;
48
49  if (incoming_frame_rate_ <= 0) return false;
50
51  const uint32_t incomingframe_rate =
52      static_cast<uint32_t>(incoming_frame_rate_ + 0.5f);
53
54  if (target_frame_rate_ == 0) return true;
55
56  bool drop = false;
57  if (incomingframe_rate > target_frame_rate_) {
58    int32_t overshoot =
59        overshoot_modifier_ + (incomingframe_rate - target_frame_rate_);
60    if (overshoot < 0) {
61      overshoot = 0;
62      overshoot_modifier_ = 0;
63    }
64
65    if (overshoot && 2 * overshoot < (int32_t) incomingframe_rate) {
66      if (drop_count_) {  // Just got here so drop to be sure.
67          drop_count_ = 0;
68          return true;
69      }
70      const uint32_t dropVar = incomingframe_rate / overshoot;
71
72      if (keep_count_ >= dropVar) {
73          drop = true;
74          overshoot_modifier_ = -((int32_t) incomingframe_rate % overshoot) / 3;
75          keep_count_ = 1;
76      } else {
77          keep_count_++;
78      }
79    } else {
80      keep_count_ = 0;
81      const uint32_t dropVar = overshoot / target_frame_rate_;
82      if (drop_count_ < dropVar) {
83          drop = true;
84          drop_count_++;
85      } else {
86          overshoot_modifier_ = overshoot % target_frame_rate_;
87          drop = false;
88          drop_count_ = 0;
89      }
90    }
91  }
92  return drop;
93}
94
95
96uint32_t VPMVideoDecimator::Decimatedframe_rate() {
97ProcessIncomingframe_rate(TickTime::MillisecondTimestamp());
98  if (!enable_temporal_decimation_) {
99    return static_cast<uint32_t>(incoming_frame_rate_ + 0.5f);
100  }
101  return VD_MIN(target_frame_rate_,
102      static_cast<uint32_t>(incoming_frame_rate_ + 0.5f));
103}
104
105uint32_t VPMVideoDecimator::Inputframe_rate() {
106  ProcessIncomingframe_rate(TickTime::MillisecondTimestamp());
107  return static_cast<uint32_t>(incoming_frame_rate_ + 0.5f);
108}
109
110void VPMVideoDecimator::UpdateIncomingframe_rate() {
111  int64_t now = TickTime::MillisecondTimestamp();
112  if (incoming_frame_times_[0] == 0) {
113    // First no shift.
114  } else {
115    // Shift.
116    for (int i = kFrameCountHistory_size - 2; i >= 0; i--) {
117        incoming_frame_times_[i+1] = incoming_frame_times_[i];
118    }
119  }
120  incoming_frame_times_[0] = now;
121  ProcessIncomingframe_rate(now);
122}
123
124void VPMVideoDecimator::ProcessIncomingframe_rate(int64_t now) {
125  int32_t num = 0;
126  int32_t nrOfFrames = 0;
127  for (num = 1; num < (kFrameCountHistory_size - 1); num++) {
128    // Don't use data older than 2sec.
129    if (incoming_frame_times_[num] <= 0 ||
130        now - incoming_frame_times_[num] > kFrameHistoryWindowMs) {
131      break;
132    } else {
133      nrOfFrames++;
134    }
135  }
136  if (num > 1) {
137    int64_t diff = now - incoming_frame_times_[num-1];
138    incoming_frame_rate_ = 1.0;
139    if (diff > 0) {
140      incoming_frame_rate_ = nrOfFrames * 1000.0f / static_cast<float>(diff);
141    }
142  } else {
143    incoming_frame_rate_ = static_cast<float>(nrOfFrames);
144  }
145}
146
147}  // namespace webrtc
148