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Explore the challenges and solutions in measuring the Quality of Experience (QoE) for IPTV deployments, including traditional measurements (QoS) vs. QoE, possible measurement approaches, and end-to-end QoE management.
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Measuring Quality of Experience for Successful IPTV Deployments Dr. Stefan Winkler
Outline • Challenges • Digital Video Quality Issues • Traditional Measurements (QoS) vs. Quality of Experience (QoE) • Possible Solutions • QoE Measurement Approaches • End-to-end QoE Management • Conclusions
Digital Video Challenges Demanding traffic profiles • High bandwidth streams • High traffic volumes • Live, VOD Network effects • Video impacted heavily with minor network impairments • Multi-vendor network complicates diagnosis / troubleshooting Service quality degradations Difficult diagnosis, troubleshooting Rising management and OPEX costs Higher customer churn High end-user expectations • Defined with decades of history • Grow rapidly with HD • Low tolerance for poor quality New architectures • Sensitive video processing devices create possibility for various impairment sources • Ad-insertion, middleware
What Drives End-Users Source: MRG 2007 IPTV Video Quality Survey, available at http://qoe.symmetricom.com
Service Providers View Source: MRG 2007 IPTV Video Quality Survey, available at http://qoe.symmetricom.com
Service Providers’ View Source: MRG 2007 IPTV Video Quality Survey, available at http://qoe.symmetricom.com
Sources of Video Issues Consider all elements for true end-to-end solution
Compression Artifacts Original MPEG-2 H.264
PSNR vs. QoE Same amount of distortion (PSNR) – different perceived quality Understand & model human vision system
Quality of Service Network-centric Delay, packet loss, jitter Transmission quality Content agnostic Quality of Experience Content impairments Blockiness, Jerkiness, … End-user quality Application driven QoS vs. QoE QoS QoE
QoS vs. QoE • Same network impairments • Packet Loss: 1% • Delay: 10ms • Jitter: 50us • Bandwidth: 500kbps • Different perceived quality!
MDI vs. QoE • Media Delivery Index (MDI) • MDI consists of two metrics: • Delay Factor (DF) • Media Loss Rate (MLR) • MDI limitations: • MDI assumes constant bit rate (CBR) traffic • MDI does not consider video payload or content • MDI values are not intuitive • MDI doesn’t correlate with video quality
MDI vs. QoE MOS Media Loss
QoS/QoE Cycle Alignment gap Service provider End-user DesiredQoE Targeted QoS Value gap Execution gap Perceived QoE DeliveredQoS Perception gap Adapted from ITU-T Rec. G.1000 and COM12–C185–E
Outline • Challenges • Digital Video Quality Issues • Traditional Measurements (QoS) vs. Quality of Experience (QoE) • Possible Solutions • QoE Measurement Approaches • End-to-end QoE Management • Conclusions
Video Video Compression/TransmissionSystem Full-Reference Approach Sender Receiver • Comparison of individual video frames • Offline analysis (capture is required) – lab applications • High detail and accuracy • Alignment procedure Full Ref. QualityMeasurement Full reference information
Video Video Compression/TransmissionSystem No-Reference Approach Sender Receiver • Non-intrusive, in-service measurement • Real-time monitoring applications • No alignment required No-Ref. QualityMeasurement
Video Video Compression/TransmissionSystem Reduced-Reference Approach Sender Receiver • Monitoring applications • Correlation of content and network impairments • Encrypted environments Feature Extraction Reduced Ref.Measurement Feature Extraction
Content & Network Metrics (Correlation Engine) "Vision is the most highly developed of the human senses, so people are even more sensitive to flaws in video images than, say, the sound of a telephone conversation.”Ken Wirt, Cisco Vice President Consumer Marketing, Jan 2008
Vision Modeling • Contrast perception • Visibility of different patterns • Frequency dependencies • Masking effects • Interaction of content and impairments • Texture, edges, luminance • Spatial and temporal masking • Color perception Sensitivity Temporal frequency [Hz] Spatial frequency [cpd] Visibility threshold Maskingcurve Thresholdwithoutmasker Target contrast Masker contrast
End-to-end QoE • Deep Content Analysis (bitstream) • Detect content impairments • Deep inspection to associate content to timestamps (eg: TS1 = I-Frame) • Deep Content Analysis(pixel by pixel) • Source content and encoder / transcoder validation • Network (header or stream) Analysis • Detect QoS issues • Content analysis where possible (unencrypted) • Inspection of QoS to associate timestamps to impairments (eg: TS1 = PacketLoss) Content Stream Analysis: • PES inspection • PCR jitter etc. Content Impairments: • Blockiness, blur • Jerkiness • Freeze/black frame • Noise, Color TS1 = I-Frame Q-Advisor Network Impairments: • Loss • Delay • Jitter • Bandwidth Correlation Engine TS1 = Packet Loss Packet Loss -> I-Frame Human Vision System Model VideoQualityReports
5 Imperceptible 4 Perceptible 3 Slightly Annoying 2 Annoying 1 Very Annoying IPTV QoE Management • 1. Understand the Service • Is there an issue? • Does it matter? • 2. Understand the Problem • What does the customer see? • What is the exact cause? 1.0 • 3. Understand the Solution • What is the impairment source?
Conclusions • QoE is application-driven • Measure both network and content impairments • QoE is user-oriented • Measure how end-user perceives service issues • End-to-end quality measurement • Cover different impairment sources • Identify problem causes
Contact Info Stefan Winklerswinkler@symmetricom.com Company:qoe.symmetricom.com Further Reading:stefan.winkler.net/book.html