1 /*
2 * Copyright (c) 2016 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 "modules/rtp_rtcp/source/rtcp_packet/tmmbn.h"
12
13 #include "modules/rtp_rtcp/source/rtcp_packet/common_header.h"
14 #include "rtc_base/checks.h"
15 #include "rtc_base/logging.h"
16
17 namespace webrtc {
18 namespace rtcp {
19 constexpr uint8_t Tmmbn::kFeedbackMessageType;
20 // RFC 4585: Feedback format.
21 // Common packet format:
22 //
23 // 0 1 2 3
24 // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
25 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
26 // |V=2|P| FMT | PT | length |
27 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
28 // | SSRC of packet sender |
29 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
30 // | SSRC of media source (unused) = 0 |
31 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
32 // : Feedback Control Information (FCI) :
33 // : :
34 // Temporary Maximum Media Stream Bit Rate Notification (TMMBN) (RFC 5104).
35 // The Feedback Control Information (FCI) consists of zero, one, or more
36 // TMMBN FCI entries.
37 // 0 1 2 3
38 // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
39 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
40 // | SSRC |
41 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
42 // | MxTBR Exp | MxTBR Mantissa |Measured Overhead|
43 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
44
45 Tmmbn::Tmmbn() = default;
46
47 Tmmbn::~Tmmbn() = default;
48
Parse(const CommonHeader & packet)49 bool Tmmbn::Parse(const CommonHeader& packet) {
50 RTC_DCHECK_EQ(packet.type(), kPacketType);
51 RTC_DCHECK_EQ(packet.fmt(), kFeedbackMessageType);
52
53 if (packet.payload_size_bytes() < kCommonFeedbackLength) {
54 RTC_LOG(LS_WARNING) << "Payload length " << packet.payload_size_bytes()
55 << " is too small for TMMBN.";
56 return false;
57 }
58 size_t items_size_bytes = packet.payload_size_bytes() - kCommonFeedbackLength;
59 if (items_size_bytes % TmmbItem::kLength != 0) {
60 RTC_LOG(LS_WARNING) << "Payload length " << packet.payload_size_bytes()
61 << " is not valid for TMMBN.";
62 return false;
63 }
64 ParseCommonFeedback(packet.payload());
65 const uint8_t* next_item = packet.payload() + kCommonFeedbackLength;
66
67 size_t number_of_items = items_size_bytes / TmmbItem::kLength;
68 items_.resize(number_of_items);
69 for (TmmbItem& item : items_) {
70 if (!item.Parse(next_item))
71 return false;
72 next_item += TmmbItem::kLength;
73 }
74 return true;
75 }
76
AddTmmbr(const TmmbItem & item)77 void Tmmbn::AddTmmbr(const TmmbItem& item) {
78 items_.push_back(item);
79 }
80
BlockLength() const81 size_t Tmmbn::BlockLength() const {
82 return kHeaderLength + kCommonFeedbackLength +
83 TmmbItem::kLength * items_.size();
84 }
85
Create(uint8_t * packet,size_t * index,size_t max_length,PacketReadyCallback callback) const86 bool Tmmbn::Create(uint8_t* packet,
87 size_t* index,
88 size_t max_length,
89 PacketReadyCallback callback) const {
90 while (*index + BlockLength() > max_length) {
91 if (!OnBufferFull(packet, index, callback))
92 return false;
93 }
94 const size_t index_end = *index + BlockLength();
95
96 CreateHeader(kFeedbackMessageType, kPacketType, HeaderLength(), packet,
97 index);
98 RTC_DCHECK_EQ(0, Rtpfb::media_ssrc());
99 CreateCommonFeedback(packet + *index);
100 *index += kCommonFeedbackLength;
101 for (const TmmbItem& item : items_) {
102 item.Create(packet + *index);
103 *index += TmmbItem::kLength;
104 }
105 RTC_CHECK_EQ(index_end, *index);
106 return true;
107 }
108 } // namespace rtcp
109 } // namespace webrtc
110