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 "webrtc/modules/rtp_rtcp/source/rtcp_packet/dlrr.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 17 namespace webrtc { 18 namespace rtcp { 19 // DLRR Report Block (RFC 3611). 20 // 21 // 0 1 2 3 22 // 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 23 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 24 // | BT=5 | reserved | block length | 25 // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ 26 // | SSRC_1 (SSRC of first receiver) | sub- 27 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ block 28 // | last RR (LRR) | 1 29 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 30 // | delay since last RR (DLRR) | 31 // +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ 32 // | SSRC_2 (SSRC of second receiver) | sub- 33 // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ block 34 // : ... : 2 35 bool Dlrr::Parse(const uint8_t* buffer, uint16_t block_length_32bits) { 36 RTC_DCHECK(buffer[0] == kBlockType); 37 // kReserved = buffer[1]; 38 RTC_DCHECK_EQ(block_length_32bits, 39 ByteReader<uint16_t>::ReadBigEndian(&buffer[2])); 40 if (block_length_32bits % 3 != 0) { 41 LOG(LS_WARNING) << "Invalid size for dlrr block."; 42 return false; 43 } 44 45 size_t blocks_count = block_length_32bits / 3; 46 const uint8_t* read_at = buffer + kBlockHeaderLength; 47 sub_blocks_.resize(blocks_count); 48 for (SubBlock& sub_block : sub_blocks_) { 49 sub_block.ssrc = ByteReader<uint32_t>::ReadBigEndian(&read_at[0]); 50 sub_block.last_rr = ByteReader<uint32_t>::ReadBigEndian(&read_at[4]); 51 sub_block.delay_since_last_rr = 52 ByteReader<uint32_t>::ReadBigEndian(&read_at[8]); 53 read_at += kSubBlockLength; 54 } 55 return true; 56 } 57 58 size_t Dlrr::BlockLength() const { 59 if (sub_blocks_.empty()) 60 return 0; 61 return kBlockHeaderLength + kSubBlockLength * sub_blocks_.size(); 62 } 63 64 void Dlrr::Create(uint8_t* buffer) const { 65 if (sub_blocks_.empty()) // No subblocks, no need to write header either. 66 return; 67 // Create block header. 68 const uint8_t kReserved = 0; 69 buffer[0] = kBlockType; 70 buffer[1] = kReserved; 71 ByteWriter<uint16_t>::WriteBigEndian(&buffer[2], 3 * sub_blocks_.size()); 72 // Create sub blocks. 73 uint8_t* write_at = buffer + kBlockHeaderLength; 74 for (const SubBlock& sub_block : sub_blocks_) { 75 ByteWriter<uint32_t>::WriteBigEndian(&write_at[0], sub_block.ssrc); 76 ByteWriter<uint32_t>::WriteBigEndian(&write_at[4], sub_block.last_rr); 77 ByteWriter<uint32_t>::WriteBigEndian(&write_at[8], 78 sub_block.delay_since_last_rr); 79 write_at += kSubBlockLength; 80 } 81 RTC_DCHECK_EQ(buffer + BlockLength(), write_at); 82 } 83 84 bool Dlrr::WithDlrrItem(uint32_t ssrc, 85 uint32_t last_rr, 86 uint32_t delay_last_rr) { 87 if (sub_blocks_.size() >= kMaxNumberOfDlrrItems) { 88 LOG(LS_WARNING) << "Max DLRR items reached."; 89 return false; 90 } 91 SubBlock block; 92 block.ssrc = ssrc; 93 block.last_rr = last_rr; 94 block.delay_since_last_rr = delay_last_rr; 95 sub_blocks_.push_back(block); 96 return true; 97 } 98 99 } // namespace rtcp 100 } // namespace webrtc 101
