1/*
2 *  Copyright (c) 2014 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/video/report_block_stats.h"
12
13namespace webrtc {
14
15namespace {
16int FractionLost(uint32_t num_lost_sequence_numbers,
17                 uint32_t num_sequence_numbers) {
18  if (num_sequence_numbers == 0) {
19    return 0;
20  }
21  return ((num_lost_sequence_numbers * 255) + (num_sequence_numbers / 2)) /
22      num_sequence_numbers;
23}
24}  // namespace
25
26
27// Helper class for rtcp statistics.
28ReportBlockStats::ReportBlockStats()
29    : num_sequence_numbers_(0),
30      num_lost_sequence_numbers_(0) {
31}
32
33void ReportBlockStats::Store(const RtcpStatistics& rtcp_stats,
34                             uint32_t remote_ssrc,
35                             uint32_t source_ssrc) {
36  RTCPReportBlock block;
37  block.cumulativeLost = rtcp_stats.cumulative_lost;
38  block.fractionLost = rtcp_stats.fraction_lost;
39  block.extendedHighSeqNum = rtcp_stats.extended_max_sequence_number;
40  block.jitter = rtcp_stats.jitter;
41  block.remoteSSRC = remote_ssrc;
42  block.sourceSSRC = source_ssrc;
43  uint32_t num_sequence_numbers = 0;
44  uint32_t num_lost_sequence_numbers = 0;
45  StoreAndAddPacketIncrement(
46      block, &num_sequence_numbers, &num_lost_sequence_numbers);
47}
48
49RTCPReportBlock ReportBlockStats::AggregateAndStore(
50    const ReportBlockVector& report_blocks) {
51  RTCPReportBlock aggregate;
52  if (report_blocks.empty()) {
53    return aggregate;
54  }
55  uint32_t num_sequence_numbers = 0;
56  uint32_t num_lost_sequence_numbers = 0;
57  ReportBlockVector::const_iterator report_block = report_blocks.begin();
58  for (; report_block != report_blocks.end(); ++report_block) {
59    aggregate.cumulativeLost += report_block->cumulativeLost;
60    aggregate.jitter += report_block->jitter;
61    StoreAndAddPacketIncrement(*report_block,
62                               &num_sequence_numbers,
63                               &num_lost_sequence_numbers);
64  }
65
66  if (report_blocks.size() == 1) {
67    // No aggregation needed.
68    return report_blocks[0];
69  }
70  // Fraction lost since previous report block.
71  aggregate.fractionLost =
72      FractionLost(num_lost_sequence_numbers, num_sequence_numbers);
73  aggregate.jitter = static_cast<uint32_t>(
74      (aggregate.jitter + report_blocks.size() / 2) / report_blocks.size());
75  return aggregate;
76}
77
78void ReportBlockStats::StoreAndAddPacketIncrement(
79    const RTCPReportBlock& report_block,
80    uint32_t* num_sequence_numbers,
81    uint32_t* num_lost_sequence_numbers) {
82  // Get diff with previous report block.
83  ReportBlockMap::iterator prev_report_block = prev_report_blocks_.find(
84        report_block.sourceSSRC);
85  if (prev_report_block != prev_report_blocks_.end()) {
86    int seq_num_diff = report_block.extendedHighSeqNum -
87                       prev_report_block->second.extendedHighSeqNum;
88    int cum_loss_diff = report_block.cumulativeLost -
89                        prev_report_block->second.cumulativeLost;
90    if (seq_num_diff >= 0 && cum_loss_diff >= 0) {
91      *num_sequence_numbers += seq_num_diff;
92      *num_lost_sequence_numbers += cum_loss_diff;
93      // Update total number of packets/lost packets.
94      num_sequence_numbers_ += seq_num_diff;
95      num_lost_sequence_numbers_ += cum_loss_diff;
96    }
97  }
98  // Store current report block.
99  prev_report_blocks_[report_block.sourceSSRC] = report_block;
100}
101
102int ReportBlockStats::FractionLostInPercent() const {
103  if (num_sequence_numbers_ == 0) {
104    return -1;
105  }
106  return FractionLost(
107      num_lost_sequence_numbers_, num_sequence_numbers_) * 100 / 255;
108}
109
110}  // namespace webrtc
111
112