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Transcript of “POLITEHNICA” UNIVERSITY OF TIMIOARA FACULTY OF ELECTRONICS AND TELECOMMUNICATIONS DEPARTMENT OF...
“POLITEHNICA” UNIVERSITY OF TIMIȘOARAFACULTY OF ELECTRONICS AND
TELECOMMUNICATIONSDEPARTMENT OF COMMUNICATIONS
DIPLOMA THESIS
VIDEO QUALITY ASSESSMENT IN MOBILE NETWORKS
Coordinate,Assoc. Prof. Eng. Dr. Eugen Mârza
Graduate,Dragoș-Florin Iancu
Timișoara 2010
07/29/2010 Dragoș Iancu 2
Contents
1) Introduction
2) Human Visual System (HVS)3) Mobile Video Streaming Principles
4) Quality Metrics
5) Conclusions
07/29/2010 Dragoș Iancu 3
Introduction
Topics of interest:• vision modeling in the framework of video quality
assessment• analysis and evaluation of different video quality
assessment methods and algorithms over a mobile network
• determining the one that performs best while
correlating well with subjective assessments• error detection and concealment (artifacts)
07/29/2010 Dragoș Iancu 4
Human Visual System
• HVS:– very complex– highly adaptive– not equally sensitive to all stimuli – visual information processed on different pathways and channels– color perception based on different spectral
sensitivities of photoreceptors
=> characteristics of the HVS used in the design of vision models and quality metrics
07/29/2010 Dragoș Iancu 5
Mobile Video Streaming Principles
• Video service request in a mobile network– wireless=error prone environment – limited bandwidth means low resolution => loss of 1
packet is a considerable loss of information– real-time => retransmission impossible
07/29/2010 Dragoș Iancu 7
Distortion Artifacts
• Blocking artifacts • Ringing artifacts• Clipping• Noise • Contrast• Sharpness• Blurriness • Jerkiness• Mosquito Noise• Shimmering• Network errors • Post-processing errors
07/29/2010 Dragoș Iancu 12
Conclusions
1. Best results with PSNR metric2. SSIM best mimics the HVS, however has
limitations 3. MOS delivers valuable information for:
– optimization – benchmarking
4. methods dependent on: – the correct receival of motion vectors– the presence of scene cuts or fast movement
5. systematic video quality assessment approaches developed to increase flexibility