IPTV Video Quality: QoS and QoE

SUMMARY

1 Executive Summary

1.1 Purpose

This report is about IPTV video quality and the quality of the IPTV experience. To frame the discussion, this report provides three separate but nested definitions relating to video quality that are of highest relevance to the business success of an IPTV service provider:

• Video Quality (VQ), which refers to the video content itself.
• Video Quality of Service (V-QoS), which refers to the error-free video delivery from the operator’s facilities to the customer premises over the broadband widearea network.
• Quality of Experience (QoE), refers to the overall IPTV user experience, including application responsiveness, functionality, usability and the service context that surrounds it. Unlike VQ and V-QoS, which are each subject to measurement and conformance to specific metrics, QoE is ensured by using a combination of objective, testable criteria and subjective, anecdotal criteria that reflect the performance of the entire IPTV delivery ecosystem.

Only by ensuring high levels of all three, can IPTV service providers begin to capture new subscribers and keep them loyal. Because MPEG-2 and MPEG-4 AVC are similar technologies, this report includes information for both MPEG-2 and MPEG-4 AVC operations. However, the emphasis in this report is on MPEG-4 AVC, since most (if not all) new IPTV systems are forecasted to use MEG-4 AVC from 2007 forward.

1.2 Situation

Telcos are fighting an uphill and increasingly fierce battle against incumbent competitors, so VQ/V-QoS and QoE are key considerations. To deliver video services, they must not only engineer their networks more deliberately and monitor them more carefully than ever before, they also must quickly come up to speed with unfamiliar IPTV infrastructure, such as the headend, TV-enabling software and CPE.

Complicating matters is the fact that many crucial IPTV infrastructure and serviceenabling elements are immature and have yet to be proven in scaled production deployments, which creates the risk of unexpected problems that affect VQ and QoE but don’t necessarily have quick fixes. We specifically make reference to IPTV middleware and interactive television applications.

1.3 IPTV Observations Relating to Quality

Because the IPTV ecosystem is complex, this report breaks it up into seven domains, which are identified in Section 3 and discussed in detail in Section 4. The complexity of this ecosystem makes it very expensive to implement. To minimize capital equipment and software costs at deployment, IPTV operators assume an oversubscription model - deploying enough equipment to serve under average conditions with statisticallydetermined peaks, as opposed to being designed for full-time peak capacity.

TABLE OF CONTENTS

1 Executive Summary

• 1.1 Purpose
• 1.2 Situation
• 1.3 IPTV Observations Relating to Quality
• 1.4 Key Recommendations

2 Overview of Video and Video Quality

• 2.1 IPTV Market and Technology Situation
  • 2.1.1 The Drive for Video Quality
  • 2.1.2 Issues Interfering with Scaleable Deployment of IPTV
• 2.2 Video Content Challenges Are Increasing
• 2.3 Definitions: IPTV, Video Quality, Video Quality of Service and Quality of Experience
  • 2.3.1 Video Quality (VQ)
  • 2.3.2 Video Quality of Service (V-QoS)
  • 2.3.3 Quality of Experience (QoE)
  • 2.3.4 Non-Video Factors Affecting Quality of Experience

3 IPTV Architecture and Reference Model

• 3.1 IPTV Domains
• 3.2 End-to-End IPTV Ecosystem Architecture
• 3.3 ISO/OSI Communications Reference Model as Relates to IPTV

4 The IPTV Delivery Ecosystem and Video Quality

• 4.1 Content Development and Production Domain
• 4.2 Acquisition Domain
  • 4.2.1 Characteristics of the Acquisition Domain
  • 4.2.2 Types of Source Content
  • 4.2.3 Variables that Affect Video Quality in the Acquisition Domain
• 4.3 Content Processing Domain
  • 4.3.1 Characteristics of the Content Processing Domain
  • 4.3.2 Video Encoding and Compression
  • 4.3.3 Bandwidth Conservation Techniques Associated with Video Encoding
  • 4.3.4 Variables that Affect Video Quality in the Content Processing Domain
• 4.4 Storage Domain
  • 4.4.1 Characteristics of the Storage Domain
  • 4.4.2 Variables Affecting Video Quality in the Storage Domain
• 4.5 Control Domain
  • 4.5.1 Characteristics of the Control Domain
  • 4.5.2 Variables Affecting Video Quality in the Control Domain
• 4.6 Distribution Domain
  • 4.6.1 Characteristics of the Distribution Domain
  • 4.6.2 Variables Affecting Video Quality in the Distribution Domain
• 4.7 Network Edge and Access Domain
  • 4.7.1 Characteristics of the Network Edge and Access Domain
  • 4.7.2 Variables Affecting Video Quality in the Edge and Access Domain
• 4.8 Customer Premises Domain
  • 4.8.1 VQ and QoE Impact at the Customer Premises Domain
• 4.9 IPTV Concerns that Span Multiple Domains
  • 4.9.1 Video Characteristics and Functionalities Occurring Across Multiple Domains
  • 4.9.2 V-QoS and QoE Strategies and Techniques Used Across Multiple Domains

5 Test and Measurement for VQ, V-QoS and QoE

• 5.1 Video Quality Measurement
  • 5.1.1 Video Signal Parameters
• 5.2 Transport and Video Quality-of-Service Measurements
• 5.3 Quality of Experience: Measurement of Interactivity
• 5.4 Quality of Experience: Holistic View
  • 5.4.1 Comparing Video Input with Video Output
• 5.5 IPTV QoE: Qualitative and Perceptual Measurements
• 5.6 Test and Measurement Across the IPTV Ecosystem

6 Conclusions

• 6.1 Complex Ecosystem to Deliver MPEG-4 Video
• 6.2 Quality of Experience (QoE) is Both Measurable and Subjective
• 6.3 Data Errors Occurring in the Network Have Major Effect on V-QoS
• 6.4 The Choice of MPEG Transport Method Has an Effect on QoE
• 6.5 Standards for QoE

7 Recommendations for Maximizing Video Quality

• 7.1 Summary of Recommendations
• 7.2 Acquisition Recommendations
  • 7.2.1 Be Prepared for Stringent Ingest Requirements From Video Programmers
  • 7.2.2 Begin Testing Before the Encoder
  • 7.2.3 Pre-Process Video Content into a Common Format
  • 7.2.4 Digital Transport and Backhaul
• 7.3 Headend Design Recommendations
  • 7.3.1 Establish the Video Service Lineup First
• 7.4 Video Encoding Recommendations
  • 7.4.1 For Distribution, Encode to the MEG-4 AVC/H.264 Format
  • 7.4.2 Establish Parameters for Video Content Errors
  • 7.4.3 Carefully Evaluate the Options for Transcoding
  • 7.4.4 Smoothing the Video Stream
• 7.5 Network Design Recommendations
  • 7.5.1 Service Level Agreements
  • 7.5.2 Design the Network to Accommodate HDTV, End-to-End
  • 7.5.3 Establish Bandwidth Budgets
  • 7.5.4 Remember to Budget for Non-Video Traffic
  • 7.5.5 Additional Network Considerations that Impact VQ & V-QoS
• 7.6 Test and Measurement Recommendations
  • 7.6.1 Deploy with a Full-Time Test and Measurement System
  • 7.6.2 Recommended Placement of Test and Measurement Systems
  • 7.6.3 Test for Impairments at the Physical Layer
  • 7.6.4 Testing to Rigid Technical Standards is Not Enough
  • 7.6.5 Perform Anecdotal Consumer Testing
• 7.7 CPE Recommendations
  • 7.7.1 Operators Must Follow the STB Recommendations of Their Software Suppliers
  • 7.7.2 Policy Management at the Set-top Box Level
  • 7.7.3 Correcting MPEG Video Errors in the Set-top Box
  • 7.7.4 Minimizing the Effect of Network Errors in the Set-top Box:
  • 7.7.5 Network Termination Device
• 7.8 Quality of Service Recommendations
• 7.9 Quality of Experience Recommendations
  • 7.9.1 Channel Change Times
  • 7.9.2 Synchronization of Audio and Video
  • 7.9.3 Prioritization of Service Traffic
  • 7.9.4 MPEG Transport Streams
  • 7.9.5 Implement Policies that Mitigate Network Issues Resulting from Oversubscription
  • 7.9.6 Content Recommendations
• 7.10 Recommendations that Impact Multiple IPTV Domains
  • 7.10.1 Implement Redundancy
  • 7.10.2 Consider Established IPTV Architecture Reference Standards
  • 7.10.3 Balance the Need for Standards Against the Virtues of Proprietary Solutions

8 Appendix 1: IP Communications Concepts Which Relate to Video Applications

• 8.1 ISO/OSI Basic Reference Model
• 8.2 IP Networking Standards
  • 8.2.1 IGMP
  • 8.2.2 RTSP
  • 8.2.3 RTP
  • 8.2.4 RTCP (Real-Time Transport Control Protocol)
  • 8.2.5 UDP

9 Appendix 2: Video and Video Communications Standards

• 9.1 MPEG Video
  • 9.1.1 MPEG Video Stream Structure
  • 9.1.2 MPEG-2
  • 9.1.3 MPEG-4
  • 9.1.4 Other Video Standards
  • 9.1.5 VC-1
  • 9.1.6 MPEG-7 and MPEG-21
• 9.2 MPEG Transport
  • 9.2.1 Approaches to MPEG Transport
  • 9.2.2 Advocacy for MPEG-2 Transport
  • 9.2.3 MPEG-2 Transport Steam Encapsulation

10 Appendix 5: IPTV Vendors

• 10.1 Video Networking Suppliers
• 10.2 Headend and Encoder Suppliers
• 10.3 IPTV Middleware Suppliers
• 10.4 Content Protection (Encryption, Watermarking) Suppliers
• 10.5 IPTV Network Suppliers
• 10.6 Test and Measurement
• 10.7 Professional Services

11 Appendix 6: Glossary of Terms

12 Index of Companies

Table of Figures

• Figure 1-1: Domains Acquisition, Storage, Control and Distribution
• Figure 1-2: Makeup of MPEG Video - Key to Controlling Packet Loss & Jitter
• Figure 1-3: Comparison of MPEG-2 vs. MPEG-4 Video Quality
• Figure 1-4: Comparing MPEG-2 and MPEG-4 Over DSL
• Figure 1-5: Potential Sample Points Across The IPTV Ecosystem
• Figure 3-1: Domains 1-5: Acquisition, Processing Storage, Control and Distribution
• Figure 3-2: Domains 5-7: IPTV Distribution, Network Edge & Access and Customer Premises
• Figure 3-3: IPTV Set-top Box Architectural Diagram
• Figure 3-4: Hypothetical Tier-1 Operator with National (Super) Headend, Regional and Local Video Facilities
• Figure 4-1: Example of Colors that are Outside of Established Color Parameters
• Figure 4-2: Comparison of MPEG-2 vs. MPEG-4 Video Quality
• Figure 4-3: Constant Bit-Rate Encoding
• Figure 4-4: Illustration of How CF-CBR Limits Bandwidth Requirements
• Figure 4-5: Aggregated Content Bundled Using CF-CBR
• Figure 4-6: Embedding of Watermarks During Video Encoding
• Figure 4-7: Application of Watermarks in the IPTV Ecosystem
• Figure 4-8: Encrypted vs. Unencrypted Video
• Figure 4-9: 1-D FEC Examples That Can Be Corrected
• Figure 4-10: 1-D Example That Cannot Be Corrected
• Figure 4-11: 2-D FEC Examples That Can Be Corrected
• Figure 4-12: 2-D FEC Examples That Can Be Corrected
• Figure 5-1: Holistic View of IPTV QoE
• Figure 5-2: Potential Sample Points Across The IPTV Ecosystem
• Figure 7-1: Comparing MPEG-2 and MPEG-4 Over DSL
• Figure 7-2: Comparison of DSL Ability to Accommodate MPEG-2 and MPEG-4 Video
• Figure 8-1: OSI ISO 7-Layer Basic Reference Model
• Figure 9-1: Model for MPEG-2 Systems
• Figure 9-2: Structure of MPEG Video
• Figure 9-3: Data Loss Propagation in MPEG-2 Video Streams
• Figure 9-4: Minimal MPEG-2 Transport Stream

Table of Tables

• Table 3-1: Mapping the 7-Layer OSI Basic Reference Model to Video
• Table 4-1: Home Network QoS Support
• Table 8-1: ISO/OSI Model - Definitions and Functions of Each Layer In The Model