1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
/*
* Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "modules/rtp_rtcp/source/rtcp_packet/fir.h"
#include <cstddef>
#include <cstdint>
#include "modules/rtp_rtcp/source/byte_io.h"
#include "modules/rtp_rtcp/source/rtcp_packet/common_header.h"
#include "modules/rtp_rtcp/source/rtcp_packet/psfb.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
namespace webrtc {
namespace rtcp {
// RFC 4585: Feedback format.
// Common packet format:
//
// 0 1 2 3
// 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
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// |V=2|P| FMT | PT | length |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | SSRC of packet sender |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | SSRC of media source (unused) = 0 |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// : Feedback Control Information (FCI) :
// : :
// Full intra request (FIR) (RFC 5104).
// The Feedback Control Information (FCI) for the Full Intra Request
// consists of one or more FCI entries.
// FCI:
// 0 1 2 3
// 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
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | SSRC |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | Seq nr. | Reserved = 0 |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Fir::Fir() = default;
Fir::Fir(const Fir& fir) = default;
Fir::~Fir() = default;
bool Fir::Parse(const CommonHeader& packet) {
RTC_DCHECK_EQ(packet.type(), kPacketType);
RTC_DCHECK_EQ(packet.fmt(), kFeedbackMessageType);
// The FCI field MUST contain one or more FIR entries.
if (packet.payload_size_bytes() < kCommonFeedbackLength + kFciLength) {
RTC_LOG(LS_WARNING) << "Packet is too small to be a valid FIR packet.";
return false;
}
if ((packet.payload_size_bytes() - kCommonFeedbackLength) % kFciLength != 0) {
RTC_LOG(LS_WARNING) << "Invalid size for a valid FIR packet.";
return false;
}
ParseCommonFeedback(packet.payload());
size_t number_of_fci_items =
(packet.payload_size_bytes() - kCommonFeedbackLength) / kFciLength;
const uint8_t* next_fci = packet.payload() + kCommonFeedbackLength;
items_.resize(number_of_fci_items);
for (Request& request : items_) {
request.ssrc = ByteReader<uint32_t>::ReadBigEndian(next_fci);
request.seq_nr = ByteReader<uint8_t>::ReadBigEndian(next_fci + 4);
next_fci += kFciLength;
}
return true;
}
size_t Fir::BlockLength() const {
return kHeaderLength + kCommonFeedbackLength + kFciLength * items_.size();
}
bool Fir::Create(uint8_t* packet,
size_t* index,
size_t max_length,
PacketReadyCallback callback) const {
RTC_DCHECK(!items_.empty());
while (*index + BlockLength() > max_length) {
if (!OnBufferFull(packet, index, callback))
return false;
}
size_t index_end = *index + BlockLength();
CreateHeader(kFeedbackMessageType, kPacketType, HeaderLength(), packet,
index);
RTC_DCHECK_EQ(Psfb::media_ssrc(), 0);
CreateCommonFeedback(packet + *index);
*index += kCommonFeedbackLength;
constexpr uint32_t kReserved = 0;
for (const Request& request : items_) {
ByteWriter<uint32_t>::WriteBigEndian(packet + *index, request.ssrc);
ByteWriter<uint8_t>::WriteBigEndian(packet + *index + 4, request.seq_nr);
ByteWriter<uint32_t, 3>::WriteBigEndian(packet + *index + 5, kReserved);
*index += kFciLength;
}
RTC_CHECK_EQ(*index, index_end);
return true;
}
} // namespace rtcp
} // namespace webrtc
|
