Untitled Document

Voice and Video Conferencing Fundamentals - Table of Contents

Foreward

by Donald R. Proctor, Senior Vice President, Voice Technology Group, Cisco.

Chapter 1 - Overview of conferencing services

Conference Types
- Ad Hoc Conferences
  - Ad Hoc Conference Initiation: Conference Button
  - Ad Hoc Conference Initiation: Meet-Me Button
- Reservationless Conferences
- Scheduled Conferences
  - Setting up Scheduled Conferences
  - Joining a Schedled or Reservationless Conference
  - Scheduled and Reservationless Conference Features
Voice and Video Conferencing Components
Video Conferencing Modes
- Voice-Activated Conferences
- Continuous Presence Conferences
- Lecture Mode and Round-Robin Conferences
Types of Endpoints
- Desktop Conferencing Systems
- Room Conferencing Systems
- Telepresence Systems
Video Controls: Far-end Camera Control
Text Overlay
Summary

Chapter 2 - Conferencing System Design and Architecture

Components of a Conferencing System
- User Interface
  - Web Portal
  - Voice and Telephony User Interface
  - Meet me button
- Conference Control
- Control Plane
  - IVR interactions within the control plane
- Media Plane
  - Player / Recorder
  - Video Mixer/Compositor
  - Video Transrater
  - Video Transcoder
  - Audio mixer
Conferencing Architectures
- Centralized Architecture
- Distributed Architecture

Accessing the Focus
Conference Policy Server
Media Server

Full-Mesh Networks

Advanced Conferencing Scenarios
- Escalation of Point to Point to Multipoint Call

Lecture Mode Conferences
Panel Mode Conference
Floor Control
Video Mixing and Switching Scenarios

Summary
References

Chapter 3 - Fundamentals of Video Compression

Evaluating Video Quality, Bitrate, and Signal-to-Noise Ratio
Video Source Formats
- Profiles and Levels
- Frame Rates, Form Factors, and Layouts
- Standard and High Definitions
- Color Formats
Basics of Video Coding
- Pre-Processing
- Post-Processing
- Encoder Overview
  - Transform Processing
  - Quantization
  - Entropy Coding
  - Binary Arithmetic Coders
  - DCT Scanning
  - Adaptive Encoding
Hybrid Coding
- Hybrid Decoder
- P-Frames
- Hybrid Encoder
- Predictor Loop
- Motion Estimation
  - 1/2 pel and 1/4 pel Motion Estimation
  - Conventions for Motion Estimation
  - Overlapped Block Motion Compensation
- B-Frames
- Predictor Loops for Parameters
- Error Resiliency
  - Error Correction
  - Start Codes
  - Reversible VLCs
  - Data Dependency Isolation
  - Redundant Slices
  - Data Prioritization
Scalable Layered Codecs
- SNR and Spatial Scalability
- Temporal Scalability
Switching Frames
Video Codecs
- Video Stream Hierarchy
- Macroblocks
- HD Capable Codecs
Summary
References

Chapter 4 - Media Control and Transport

Overview of RTP
- RTP Header
  - First Octet in the Header
  - Payload Type
  - Sequence Number
  - Time stamp
  - Synchronization Source Identifier
  - Contributing Source (CSRC) Identifiers
  - Payload Header
  - Payload
- RTP Port Numbers
- SSRC Collisions
- RTP Header Extensions
Overview of RTCP
- RTCP Packet Headers
- RTCP Sender Report
- RTCP Receiver Report
- RTCP Source Description (SDES)
- RTCP BYE
- RTCP APP
RTP Devices in Conference Systems
- RTP Translator
  - Media Termination Points
  - Transcoders and Transraters
- RTP Mixer
- Audio Mixer
- Video MCU
- Video Switcher
Video Stream RTP Formats
- H.263
  - H.263-1996
  - H.263-1998 and H.263-2000
  - Key Frame Detection in H.263
- H.264
  - Basic Packet Structure
  - SNALU
  - Aggregation Packet
  - Fragmentation Unit Packet
  - Key Frame Detection in H.264
Detecting Stream Loss
Summary
References

Chapter 5: Signaling Protocols: Conferencing Using SIP

SIP Overview
- User Agent
- Proxy Server
- Redirect Server
- Registrar
SIP Transactions and Dialogs
SIP Messages
- SIP Requests
  - Request Line
  - Request Headers
- SIP Responses
SIP Record Routing
Event Subscription and Notification
Session Description Protocol
SIP Conferencing Models
- Conference URI
- Early and Delayed Offer
- DTMF Support
  - RFC 2833
  - KPML
Ad-hoc Audio Conferencing
Ad-hoc Video Conferencing
- Video SDP Extensions
  - H.261 Codec Attributes
  - H.263 Codec Attributes
  - H.264 Codec Attributes
- Bandwidth Information in the SDP
- Multiple Stream Support and Grouping of Media Lines
- Escalation and De-escalation
- Media Control Support
Scheduled Conferences
- Entry IVR
- In-Conference Features
- Roll Call
- Hold and Resume
- Mute and Unmute
- Outdial
RSVP/QoS Support in Conferencing Flows
Summary
References

Chapter 6 - Signaling Protocols: Conferencing Using H.323

H.323 Overview
H.323 Endpoint Aliasing
H.225 Call Signaling
- H.225 Message Format
- Common H.225 Message Types Used in H.323 Signaling
  - Setup Message
H.245 Control Protocol
- H.245 Messages
  - Terminal Capability Set
  - Simultaneous Capability Set
  - H.245 User Input Indications
  - Indicating DTMF Relay Support in the TCS Message
  - Master-Slave Determination
  - Open Logical Channel Requests
  - Open Logical Chanel Acknowledgment
  - Close Logical Channel
  - Close Logical Channel Acknowledgment
  - Request Channel Close
  - H.245 EndSession Command
- Video-Specific H.245 Messages
  - H.245 Flow Control Command
  - H.245 Miscellaneous Indication
  - H.245 Miscellaneous command
- H.323 Fast Connect Mode
Using the Empty Capability Set
- Call Hold Signaling with the Empty Capability Set
- Call Transfer with the Empty Capability Set
H.323 Device Types
- H.323 Terminals
- H.323 Gateways
- H.323 Multipoint Control Units
- H.323 Gatekeepers
H.323 Gatekeeper Services
- Required H.323 Gatekeeper Features
  - Address Translation
  - Bandwidth Control
  - Admission Control
  - Zone Management
- Optional H.323 Gatekeeper Features
  - Call Authorization
  - Call Management
  - Bandwidth Management
- Gatekeeper Signaling Options
  - Direct Endpoint Signaling
  - Gatekeeper Routed Call Signaling
- Gatekeeper RAS Signaling
  - RAS Gatekeeper Discovery
  - RAS messages
- Mid-call bandwidth requests
  - Request Request
  - Disengage confirm
- Configuring a Gatekeeper in Cisco Unified CallManager
- Configuring Gatekeeper Support in a Cisco IOS Router
- H.225 Call Setup for Video Devices Using a Gatekeeper
Using Service Prefixes with MCUs
Summary
References

Chapter 7 - Lip Synchronization in Video Conferencing

Understanding Lip Sync Skew
- Human Perceptions
- Measuring skew
- Delay Accumulation
- Delays in the Network Path
Lip sync approaches
- Poor Man's Lip Sync
- Common Reference Lip Sync
Understanding the Sender Side
- Sender audio path
- Video Source Format
  - Low Resolution Video Input
  - High Resolution Video Input
- Sender Video Path
Understanding the Receive Side
- Audio Receiver Path
- Receiver Video Path
- Types of Playout devices
RTP
- Cannonical RTP model
- RTP Time Stamps
- Using RTP for Buffer Level Management
Correlating timebases using RTCP
- NTP
- Forming RTCP packets
- Using RTCP for media synchronization
- Lip Sync policy
Summary
References

Chapter 8 - Security Design in Conferencing

Security Fundamentals
Threats
- Confidentiality Attacks
- Denial of Service Attacks
  - Depletion of Network Bandwidth
  - Depletion of Server Resources
  - Replay Attacks
  - Malware
  - Connection Hijacking
  - RTP Hijacking
- Authentication and Identity Attacks
  - Theft of Service
  - Man-in-the-middle (MitM) Attacks
- Network Infrastructure Attacks
  - Reconnaissance
  - Layer 2 Attacks
  - CAM Table Flooding
  - ARP Cache Poisoning
  - DHCP Exhaustion
  - Rogue DHCP Servers
- Endpoint Infrastructure Attacks
  - Desktop Endpoint Attacks
  - Firmware Attacks
  - Rogue Configuration Files
- Servers Attacks
  - General Port-Based Attacks
  - Web Server Vulnerabilities
  - Unneeded Services and Insecure Services
Configuring Basic Security
Port Usage
- H.323 Port Usage
  - H.323 Call Flow
  - H.323 Port Summary
- SIP Port Usage
- SCCP Port Usage
- Preset Port Numbers
NAT and PAT
- NAT Classifications
  - NAT Mapping Characteristics
  - NAT Filtering Characteristics
  - The Symmetric NAT
- NAT Complications for VoIP Protocols
- NAT ALGs
- NAT/FW Traversal Solutions
  - VPN
  - ISDN Gateway
  - Universal Plug-and-Play (UPnP)
  - IP-IP gateway inside the firewall
  - H.460
  - NAT/FW Traversal Using STUN/TURN/ICE
Encryption Basics
- Symmetric Encryption
- Secure Hashes
- Asymmetric Encryption: Public Key Cryptography
  - Public Key Encryption
  - Digital Signatures
  - Certificates
  - Certificate Management
- Nonrepudiation
- Key Distribution
  - Certificates
  - Diffie-Hellman
IPsec and TLS for Secure Signaling
- IPsec
- TLS
Media Encryption
- security-descriptions
- MIKEY
H.323 Encryption: H.235
- H.235.1
- H.235.2
- H.235.3
- H.235.6
SIP Encryption
- SIP-Digest
- SCCP Encryption
Summary
References

Appendix A - Video codec Standards

Video Codecs
- H.261 Compression Standard
- H.263 Compression Standard
- Additional H.263 Annexes
  - Annex C
  - Annex L
  - Annex N
  - Annex P
  - Annex Q
  - Annex U
  - Annex W
  - Annex X
- H.264 Compression Standard
  - Video Formats
  - Motion Vectors
  - B-frames
  - Intra prediction
  - Integer Transform
  - Quantization
  - Entropy Coding
  - Deblocking Filter
  - H.264 Error Resilience
  - H.264-SVC
- MPEG-4 Part 2
  - Video Formats
  - Motion Vectors
  - Prediction of DCT Coefficients
  - Quantization
  - Entropy Coding
  - B Frames
  - Scalability
Codecs, Bitrates and Annexes Supported by Endpoints
Summary
References

Appendix A: Video Codec Standards

H.261 Compression Standard
H.263 Compression Standard
Additional H.263 Annexes
- Annex C
- Annex L
- Annex N
- Annex P
- Annex Q
- Annex U
- Annex W
- Annex X
H.264 Compression Standard
- Video Formats
- Motion Vectors
- B-Frames
- Intra Prediction
- Integer Transform
- Quantization
- Entropy Coding
- Deblocking Filter
- H.264 Error Resilience
- H.264-SVC
MPEG-4, Part 2
- Video Formats
- Motion Vectors
- Prediction of DCT Coefficients
- Quantization
- Entropy Coding
- B-Frames
- Scalability
- Codecs, Bit Rates, and Annexes supported by Endpoints
Summary
References