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Voice and Video Conferencing Fundamentals (Fundamentals)
In past years, video conferencing has been something of a novelty. There has been a certain tolerance for quality problems as audio and video conferencing moves more into the mainstream. Customers and end-users will demand greater performance, relability, security, and scalability from their systems. Voice and Video Conferencing Fundamentals provides
readers with in-depth insight into the conferencing technologies and associated protocols. The information provided will enable Information Technology managers and engineers to understand basic concepts of video conferencing. Understanding the characteristics of video streams, encoding/decoding schemes, and features are important aspects of deployment. The valuable information found in this book will be extremely helpful during implementation and when performing vendor evaluations and making buying decisions. The book presents the architectural and technology basics of implementing audio and video conferencing over IP networks. Written by technical leaders who have years of experience in voice and video conferencing systems at Cisco Systems, this book delivers the most authoritative coverage of the conferencing technologies. Readers will find very clear discussions on the concepts and principles of audio and video conferencing systems. More comprehensive coverage is given for the advanced video architectures, such as emerging video codecs, audio/video synchronization, and distributed implementations.
Contents:
Foreword xviii Introduction xix Chapter 1 Overview of Conferencing Services 3 Conference Types 3 Ad Hoc Conferences 4 Reservationless Conferences 5 Scheduled Conferences 6 Voice and Video Conferencing Components 9 Video Conferencing Modes 11 Voice-Activated Conferences 11 Continuous Presence Conferences 13 Lecture Mode and Round-Robin Conferences 15 Types of Endpoints 16 Desktop Conferencing Systems 16 Room Conferencing Systems 16 Telepresence Systems 16 Video Controls: Far-End Camera Control 17 Text Overlay 18 Summary 18 Chapter 2 Conferencing System Design and Architecture 21 Components of a Conferencing System 21 User Interface 23 Conference Control 25 Control Plane 26 Media Plane 27 Conferencing Architectures 37 Centralized Architecture 37 Distributed Architecture 38 Full-Mesh Networks 40 Advanced Conferencing Scenarios 41 Escalation of Point-to-Point-to-Multipoint Call 41 Lecture Mode Conferences 41 Panel Mode Conference 42 Floor Control 42 Video Mixing and Switching Scenarios 42 Summary 43 References 43 Chapter 3 Fundamentals of Video Compression 45 Evaluating Video Quality, Bit Rate, and Signal-to-Noise Ratio 45 Video Source Formats 47 Profiles and Levels 47 Frame Rates, Form Factors, and Layouts 47 Standard and High Definitions 48 Color Formats 49 Basics of Video Coding 52 Preprocessing 52 Post-Processing 54 Encoder Overview 55 Hybrid Coding 72 Hybrid Decoder 72 P-Frames 74 Hybrid Encoder 74 Predictor Loop 76 Motion Estimation 77 B-Frames 82 Predictor Loops for Parameters 86 Error Resiliency 88 Scalable Layered Codecs 91 SNR and Spatial Scalability 93 Temporal Scalability 95 Switching Frames 99 Video Codecs 100 Video Stream Hierarchy 100 Macroblocks 101 HD-Capable Codecs 102 Summary 102 References 103 Chapter 4 Media Control and Transport 105 Overview of RTP 105 RTP Header 107 RTP Port Numbers 111 SSRC Collisions 111 RTP Header Extensions 112 Overview of RTCP 113 RTCP Packet Headers 113 RTCP Sender Report 114 RTCP Receiver Report 116 RTCP Source Description (SDES) 117 RTCP BYE 119 RTCP APP 120 RTP Devices in Conference Systems 120 RTP Translator 120 RTP Mixer 123 Audio Mixer 123 Video MCU 124 Video Switcher 124 Video Stream RTP Formats 126 H.263 126 H.264 133 Detecting Stream Loss 141 Summary 142 References 143 Chapter 5 Signaling Protocols: Conferencing Using SIP 145 SIP Overview 145 User Agent 146 Proxy Server 146 Redirect Server 147 Registrar 147 SIP Transactions and Dialogs 148 SIP Messages 149 SIP Requests 149 SIP Responses 152 SIP Record Routing 153 Event Subscription and Notification 154 Session Description Protocol 155 SIP Conferencing Models 157 Conference URI 157 Early and Delayed Offer 158 DTMF Support 159 Ad Hoc Audio Conferencing 160 Ad Hoc Video Conferencing 162 Video SDP Extensions 163 Bandwidth Information in the SDP 167 Multiple Stream Support and Grouping of Media Lines 168 Escalation and De-escalation 169 Media Control Support 172 Scheduled Conferences 173 Entry IVR 174 In-Conference Features 177 Roll Call 177 Hold and Resume 178 Mute and Unmute 179 Outdial 179 RSVP/QoS Support in Conferencing Flows 180 Summary 182 References 183 Chapter 6 Signaling Protocols: Conferencing Using H.323 185 H.323 Overview 185 H.323 Endpoint Aliasing 187 H.225 Call Signaling 188 H.225 Message Format 188 Common H.225 Message Types Used in H.323 Signaling 189 H.245 Control Protocol 191 H.245 Messages 192 Video-Specific H.245 Messages 202 H.323 Fast Connect Mode 204 Using the Empty Capability Set 207 Call Hold Signaling with the Empty Capability Set 207 Call Transfer with the Empty Capability Set 207 H.323 Device Types 208 H.323 Gatekeeper Services 209 Required H.323 Gatekeeper Features 209 Optional H.323 Gatekeeper Features 210 Gatekeeper Signaling Options 211 Gatekeeper RAS Signaling 212 Mid-Call Bandwidth Requests 214 Configuring a Gatekeeper in Cisco Unified CallManager 215 Configuring Gatekeeper Support in a Cisco IOS Router 217 H.225 Call Setup for Video Devices Using a Gatekeeper 217 Using Service Prefixes with MCUs 219 Summary 220 References 220 Chapter 7 Lip Synchronization in Video Conferencing 223 Understanding Lip Sync Skew 223 Human Perceptions 223 Measuring Skew 225 Delay Accumulation 226 Delays in the Network Path 228 Lip Sync Approaches 229 Poor Man's Lip Sync 230 Common Reference Lip Sync 232 Understanding the Sender Side 232 Sender Audio Path 233 Video Source Format 235 Sender Video Path 238 Understanding the Receive Side 241 Audio Receiver Path 241 Receiver Video Path 243 Types of Playout Devices 244 RTP 244 Canonical RTP Model 244 RTP Time Stamps 246 Using RTP for Buffer-Level Management 247 Correlating Timebases Using RTCP 250 NTP 250 Forming RTCP Packets 251 Using RTCP for Media Synchronization 252 Lip Sync Policy 254 Summary 255 References 255 Chapter 8 Security Design in Conferencing 257 Security Fundamentals 257 Threats 258 Confidentiality Attacks 258 Denial-of-Service Attacks 259 Authentication and Identity Attacks 262 Network Infrastructure Attacks 263 Endpoint Infrastructure Attacks 266 Server Attacks 267 Configuring Basic Security 269 Port Usage 270 H.323 Port Usage 270 SIP Port Usage 275 SCCP Port Usage 275 Preset Port Numbers 276 NAT and PAT 276 NAT Classifications 277 NAT Complications for VoIP Protocols 284 NAT ALGs 285 NAT/FW Traversal Solutions 285 Encryption Basics 299 Symmetric Encryption 299 Secure Hashes 299 Asymmetric Encryption: Public Key Cryptography 300 Nonrepudiation 309 Key Distribution 309 IPsec and TLS for Secure Signaling 310 IPsec 311 TLS 311 Media Encryption 312 security-descriptions 312 MIKEY 313 H.323 Encryption: H.235 313 H.235.1 314 H.235.2 316 H.235.3 319 H.235.6 319 SIP Encryption 321 SIP-Digest 321 SCCP Encryption 324 Summary 324 References 325 Appendix A Video Codec Standards 327 021907TOC1587052687
Brief Description:
Helps you master the fundamentals of building a voice and video conferencing network. This book presents the architectural and technology basics of implementing audio and video conferencing over IP networks. It also covers the advanced video architectures, such as emerging video codecs, audio/video synchronization, and distributed implementations.
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