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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 "webrtc/modules/rtp_rtcp/source/rtcp_packet/sli.h" | |
12 | |
13 #include "webrtc/base/checks.h" | |
14 #include "webrtc/base/logging.h" | |
15 #include "webrtc/modules/rtp_rtcp/source/byte_io.h" | |
16 #include "webrtc/modules/rtp_rtcp/source/rtcp_packet/common_header.h" | |
17 | |
18 namespace webrtc { | |
19 namespace rtcp { | |
20 constexpr uint8_t Sli::kFeedbackMessageType; | |
21 // RFC 4585: Feedback format. | |
22 // | |
23 // Common packet format: | |
24 // | |
25 // 0 1 2 3 | |
26 // 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 | |
27 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |
28 // |V=2|P| FMT | PT | length | | |
29 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |
30 // | SSRC of packet sender | | |
31 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |
32 // | SSRC of media source | | |
33 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |
34 // : Feedback Control Information (FCI) : | |
35 // : : | |
36 // | |
37 // Slice loss indication (SLI) (RFC 4585). | |
38 // FCI: | |
39 // 0 1 2 3 | |
40 // 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 | |
41 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |
42 // | First | Number | PictureID | | |
43 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |
44 Sli::Macroblocks::Macroblocks(uint8_t picture_id, | |
45 uint16_t first, | |
46 uint16_t number) { | |
47 RTC_DCHECK_LE(first, 0x1fff); | |
48 RTC_DCHECK_LE(number, 0x1fff); | |
49 RTC_DCHECK_LE(picture_id, 0x3f); | |
50 item_ = (first << 19) | (number << 6) | picture_id; | |
51 } | |
52 | |
53 void Sli::Macroblocks::Parse(const uint8_t* buffer) { | |
54 item_ = ByteReader<uint32_t>::ReadBigEndian(buffer); | |
55 } | |
56 | |
57 void Sli::Macroblocks::Create(uint8_t* buffer) const { | |
58 ByteWriter<uint32_t>::WriteBigEndian(buffer, item_); | |
59 } | |
60 | |
61 bool Sli::Parse(const CommonHeader& packet) { | |
62 RTC_DCHECK_EQ(packet.type(), kPacketType); | |
63 RTC_DCHECK_EQ(packet.fmt(), kFeedbackMessageType); | |
64 | |
65 if (packet.payload_size_bytes() < | |
66 kCommonFeedbackLength + Macroblocks::kLength) { | |
67 LOG(LS_WARNING) << "Packet is too small to be a valid SLI packet"; | |
68 return false; | |
69 } | |
70 | |
71 size_t number_of_items = | |
72 (packet.payload_size_bytes() - kCommonFeedbackLength) / | |
73 Macroblocks::kLength; | |
74 | |
75 ParseCommonFeedback(packet.payload()); | |
76 items_.resize(number_of_items); | |
77 | |
78 const uint8_t* next_item = packet.payload() + kCommonFeedbackLength; | |
79 for (Macroblocks& item : items_) { | |
80 item.Parse(next_item); | |
81 next_item += Macroblocks::kLength; | |
82 } | |
83 | |
84 return true; | |
85 } | |
86 | |
87 bool Sli::Create(uint8_t* packet, | |
88 size_t* index, | |
89 size_t max_length, | |
90 RtcpPacket::PacketReadyCallback* callback) const { | |
91 RTC_DCHECK(!items_.empty()); | |
92 while (*index + BlockLength() > max_length) { | |
93 if (!OnBufferFull(packet, index, callback)) | |
94 return false; | |
95 } | |
96 CreateHeader(kFeedbackMessageType, kPacketType, HeaderLength(), packet, | |
97 index); | |
98 CreateCommonFeedback(packet + *index); | |
99 *index += kCommonFeedbackLength; | |
100 for (const Macroblocks& item : items_) { | |
101 item.Create(packet + *index); | |
102 *index += Macroblocks::kLength; | |
103 } | |
104 return true; | |
105 } | |
106 | |
107 } // namespace rtcp | |
108 } // namespace webrtc | |
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