1 /*
2 * Copyright (c) 2015 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/pli.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 Pli::kFeedbackMessageType;
20 // RFC 4585: Feedback format.
21 //
22 // Common packet format:
23 //
24 // 0 1 2 3
25 // 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
26 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
27 // |V=2|P| FMT | PT | length |
28 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
29 // | SSRC of packet sender |
30 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
31 // | SSRC of media source |
32 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
33 // : Feedback Control Information (FCI) :
34 // : :
35
36 Pli::Pli() = default;
37
38 Pli::Pli(const Pli& pli) = default;
39
40 Pli::~Pli() = default;
41
42 //
43 // Picture loss indication (PLI) (RFC 4585).
44 // FCI: no feedback control information.
Parse(const CommonHeader & packet)45 bool Pli::Parse(const CommonHeader& packet) {
46 RTC_DCHECK_EQ(packet.type(), kPacketType);
47 RTC_DCHECK_EQ(packet.fmt(), kFeedbackMessageType);
48
49 if (packet.payload_size_bytes() < kCommonFeedbackLength) {
50 RTC_LOG(LS_WARNING) << "Packet is too small to be a valid PLI packet";
51 return false;
52 }
53
54 ParseCommonFeedback(packet.payload());
55 return true;
56 }
57
BlockLength() const58 size_t Pli::BlockLength() const {
59 return kHeaderLength + kCommonFeedbackLength;
60 }
61
Create(uint8_t * packet,size_t * index,size_t max_length,PacketReadyCallback callback) const62 bool Pli::Create(uint8_t* packet,
63 size_t* index,
64 size_t max_length,
65 PacketReadyCallback callback) const {
66 while (*index + BlockLength() > max_length) {
67 if (!OnBufferFull(packet, index, callback))
68 return false;
69 }
70
71 CreateHeader(kFeedbackMessageType, kPacketType, HeaderLength(), packet,
72 index);
73 CreateCommonFeedback(packet + *index);
74 *index += kCommonFeedbackLength;
75 return true;
76 }
77
78 } // namespace rtcp
79 } // namespace webrtc
80