layer-encoded video in scalable adaptive streaming
DESCRIPTION
Layer-Encoded Video in Scalable Adaptive Streaming. Michael Zink, Jens Schmitt, and Ralf Steinmetz , Fellow, IEEE IEEE TRANSACTIONS ON MULTIMEDIA, VOL. 7, FEBRUARY 2005. Outline. What is scalable adaptive streaming? Maximize the quality of the cached video - PowerPoint PPT PresentationTRANSCRIPT
1
Layer-Encoded Video in Scalable Adaptive Streaming
Michael Zink, Jens Schmitt,and Ralf Steinmetz, Fellow, IEEE
IEEE TRANSACTIONS ON MULTIMEDIA, VOL. 7, FEBRUARY 2005
2
Outline
What is scalable adaptive streaming?Maximize the quality of the cached video
Average PSNR is not a good assessmentSubjective impression of variations in layer-encoded video
Retransmission schedulingSimulation resultsConclusion
3
What is scalable adaptive streaming
Main goal:Provide a true video-on-demand (TVoD) system
Issues:Quality Adaptation (congestion control)
Layer-encoded techniqueScalability (performance)
Proxy caching
10
How to assess the quality of video
Use a subjective assessment
The experiment was performed with 94 test candidates
(62 males and 32 females), between the age of 14 and 64.
Video:Consists of 4 layersThe size of the nth layer:
sn = 2sn-1
11
Subjective assessment v.s PSNR (1/2)
Six variations in layer-encoded video
Farm1–Amplitude: Decrease slightly has better quality
Farm2–Frequency: Lesser layer changes has higher quality
12
Subjective assessment v.s PSNR (1/2)
M&C1–Closing the Gap:Close a gap in a lower layer has higher quality
M&C2–Constancy:No layer changes has better quality
13
Subjective assessment v.s PSNR (2/2)
M&C3–Constancy at a Higher Level:
Tennis1–All is Well That Ends Well:Increasing the amount of layers in the end leads to a higher quality
14
Compare Subject and PSNR quality
Subject assessment is more precise than PSNR. s(v) represents the same result as subject assessment.
Minimize the frequency and amplitude will have the better quality (reducing the layer variations).
15
When to schedule the retransmissions
Retransmission time:Directly after the initial streaming processDuring subsequent requestsDuring requests for different content from the server
16
How to schedule the retransmissions
Scheduling goals:Decreasing quality variations for a cached video is important.Minimize both frequency of variations and amplitude of variations.
s(v): spectrum
frames
layer
s
17
Algorithms for retransmission scheduling (1/3)
Optimal retransmission schedulingis a discrete nonlinear stochastic optimization problem (NP-complete)
Heuristics for retransmission schedulingUnrestricted priority-based heuristics
Send periodic retransmission requests to the server to ensure that the server obtains an up-to-date schedule of retransmissions.
19
Algorithms for retransmission scheduling (2/3)
Three heuristics of unrestricted priority-based retransmission scheduling algorithm:
Case1 : Unrestricted lowest layer first (U-LLF)
20
Algorithms for retransmission scheduling (3/3)
Case2 : Unrestricted shortest gap lowest layer first (U-SG-LLF)
Case3 : Unrestricted lowest layer shortest gap first (U-LL-SGF)
21
Simulation results (1/2)
22
Simulation results (2/2)
23
Conclusion
Promise a scalable TCP-friendly TVoD system
Scalable adaptive systemUse both caching and layer-encoded
Develop the retransmission algorithms to retransmit missing segments
Minimize the frequency and amplitude of the variations of the cached video