Path Diversity for Media Streaming
The Use of Multiple Description Coding
J. Apostolopoulos, M. Trott and W. Tan
Presented by Xiaoyuan GUO
Outline
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Introduction
Path Diversity
Multiple Description Coding
Systems Design, Analysis and Operation
Applications and Architectures
Summary
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Outline
Background and Motivation
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Media Streaming Characteristics
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Best-effort packet networks(i.g. Internet)
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Delay sensitive
Loss tolerant
Delay, loss rate and available bandwidth dynamic
and unpredictable
The default path is often not the best path
many applications(e.g. multicast or broadcast)
lack a back channel or other means for
retransmission
Media streaming is quite challenging
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Introduction
Solution
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Path diversity + Multiple Description Coding
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Introduction
Outline
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Introduction
Path Diversity
Multiple Description Coding
Systems Design, Analysis and Operation
Applications and Architectures
Summary
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Introduction
Definition and Categories
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Diversity: frequency, time and spatial
A transmission technique that sends data
through two or more paths in a packet-based
network
Categories
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Transmission methods
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Use multiple paths at the same time
Select best path
Source numbers
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Path Diversity
Single Source
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Path diversity using single source
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Path Diversity
Multiple sources
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Path diversity using multiple sources
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Path Diversity
Benefits
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Benefits of path diversity
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Bandwidth aggregation(use all at once)
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Traffic load balancing
Reduce probability of service outage, i.g. streaming
from multiple servers in CDN or from multiple peers in
P2P
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Path Diversity
Reduce delay and jitter
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Reduce delay and delay jitter
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Queue diversity
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Helpful
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Network delay due to backlogged queue
Benefits of multiple parallel queue
Time-invariant paths having different but unknown delay
characteristics
Applications of end-to-end delay constraint while maintaining
quality
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Path Diversity
Reduce loss
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Reduce losses
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Path selection
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When a single path system is unreliable and with feedback
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Path Diversity
Reduce Uncertainty
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Reduce uncertainty with averaging loss rate
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Time-invariant paths lack feedback
Time-varying paths that measurement lags variation
Broadcast or multicast scenarios
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Path Diversity
Reduce Loss
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Decrease the probability of outage
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Reduce the length of burst losses
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Outage: all communication along a network path is lost for a
sizable length of time
Single path p while two paths p^2
Increase the interpacket space on each path
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Path Diversity
Outline
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Introduction
Path Diversity
Multiple Description Coding
Systems Design, Analysis and Operation
Applications and Architectures
Summary
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Outline
What is it?
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Descriptions: sets of compressed data
The more descriptions available, the better
the quality of the reproduction
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Multiple Description Coding
Why Use MD?
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SD vs. SC vs. MD
SD(single description)
SC(Scalable coding)
MD(multiple des.)
No scalable
Scalable
Scalable
No priority
Priority to base layer
No priority
High code efficiency Acceptable code
efficiency
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Acceptable code
efficiency
Multiple Description Coding
Why Use MD?(2)
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Best-effect network
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Path diversity system
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Packets equally to be lost or delayed
Send descriptions over different paths
Enhance the benefits of multiple paths
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Multiple Description Coding
How Good MD Can Do?
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Rate-distortion theory
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gives theoretical bounds for how much
compression can be achieved using lossy
compression methods
Rate-distortion function D(R) give the min.
achievable average distortion D when source is
described using R bits per source symbol
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Gaussian source
D(R)=2^(-2R)
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Multiple Description Coding
R/D for Multiple Description
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Rate-distortion for multiple description
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Single- and multiple-description upper bound can
not be achieved simultaneously
Trade-off curve is known only for Gaussian source
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No obstacle to practical exploration
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Refer to L. Ozarow. “On a Source Coding Problem with
Two Channels and Three Receivers,”
Growing literatures on practical schemes
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Multiple Description Coding
MD Speech and Audio Coding
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Sequence of packets and sensitive to loss
Frame even/odd samples coded and
sent in separate packets
Path diversity: Independently of the
neighboring frame reduce burst loss
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Multiple Description Coding
MD Image Coding
subsampling
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Source coding
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MD-FEC
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+ FEC
transform coding
Scalable, prioritized nonprioritized
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Multiple Description Coding
MD-EFC
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Multiple Description Coding
MD-FEC(2)
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Flexibility
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Any number of scalable layers
Various amounts of FEC per layers
Arbitrary number of descriptions
Refer to R. Puri and K. Ramchandran. “Multiple
Description Source Coding Using Forward Error
Correction Codes”
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Multiple Description Coding
MD Video Coding
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Consecutive video frames similar
Predictive coding
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Two design extremes
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Maintain good quality even when half data is lost
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Maximize coding efficiency
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Accomplished independent prediction loops
Single prediction loop
Mismatch with subsequent error propagation
Trade-off between coding efficiency and
resilience to full or partial loss of stream
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Multiple Description Coding
MD Video Coding(2)
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Small number of description streams
Scalable MD coding(i.g. MD-FEC)
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Refer to B. Heng, J. G. Apostolopoulos, and J. S. Lim.
“End-to-End Rate-Distortion Optimized MD Mode
Selection for Multiple Description Video Coding,”
Large number of description streams
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Multiple Description Coding
Repairable MD Coding
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Error propagation in predictive coding
Repairable MD coding attempt to stop error
propagation
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repairs one description using uncorrupted frames
from the other description as long as not all the
descriptions are simultaneously lost
Complemented with path diversity
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Multiple Description Coding
Repairable MD Coding
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Multiple Description Coding
Outline
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Introduction
Path Diversity
Multiple Description Coding
Issues on Systems Design, Analysis and
Operation
Applications and Architectures
Summary
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Outline
Issues on System Design
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Joint and disjoint paths
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Multiple paths maybe independent
bottlenecks occur on shard portion impact
Identify bottlenecks and avoid them
How many paths to use
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Specifics of the application
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Benefits that one is trying to exploit
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Repairable MD coding, two paths enough
number of paths increase, aggregated bandwidth
increases, probability of outage decrease and delay
variability decrease
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System Design, Analysis and Operation
Issues on System Analysis
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Select the best paths or best servers
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Characteristics of the available paths
Min. distance while max. path diversity
Model path diversity performance
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Goal
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Select the best subset of possible servers
Select the best subset of paths
Compare path diversity scenarios
One distortion model for MD with two path
diversity
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System Design, Analysis and Operation
State Transition Pro. Model
00: two descriptions are correctly received
01/10: one description is correctly received
11:two descriptions are lost simultaneously
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System Design, Analysis and Operation
One Path Diversity Model
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Simplify network topologies
Refer to J. G. Apostolopoulos, W. Tan, S. J. Wee, and G.
W. Wornell. “Modeling Path Diversity for Multiple
Description Video Communication,”
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System Design, Analysis and Operation
Issues on System Operation
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Streaming and packet scheduling across
asymmetric paths
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Path measurement
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Rate adaption
Packet scheduling
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Estimate the characteristics of each path, i.g. timevarying, available bandwidth, etc.
More important packet may be sent over the path with
lower packet loss rate
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System Design, Analysis and Operation
Outline
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2016/3/14
Introduction
Path Diversity
Multiple Description Coding
Systems Design, Analysis and Operation
Applications and Architectures
Summary
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Outline
Low-delay application
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Low-delay applications(i.g. VoIP)
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Choose a low-latency path
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Skype using nodes in internet to bypass firewall and
NATS
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Applications and Architectures
CDN
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Using multiple paths simultaneously
Content delivery networks
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Choose a good/best server by multiple path
selection
Multiple servers provide path diversity with SD
and FEC
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MD-CDN design and operation
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Multiple resources stream packets to client
Refer to W. Tan et al. “On Multiple Description
Streaming with Content Delivery Networks”
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Applications and Architectures
P2P
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Peer-to-Peer networks
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One essential challenge
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Provide an uninterrupted flow of data to each client for
the duration of the streaming session
Multiple servers reduce service outages in the
face of uncertain peer and network condition
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Applications and Architectures
Wireless network
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Path diversity over wireless network
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Characteristics of wireless network
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Time-varying and unpredictable behavior caused by
multiple users, interface, propagation effects and
mobility
Reduce uncertainty and improve reliabilities
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Applications and Architectures
Architectures
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Control packet routes
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Relay host
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Source routing
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Direct different streams over different paths to send
each stream to different relay hosts
Forward streams to their final destinations
Specify the set of nodes for each packet to traverse
Specify different source routes for different subsets of
packets
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Applications and Architectures
Outline
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2016/3/14
Introduction
Path Diversity
Multiple Description Coding
Systems Design, Analysis and Operation
Applications and Architectures
Summary
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Outline
Summary
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Provide a survey of the benefits, architecture,
system design issues and open problems
associated with streaming delivery using path
diversity
Path diversity
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Overcome dynamic and unpredictable available
bandwidth, delay and loss rate
Take a step closer to feedback-free video streaming
VoIP, CDN, P2P,WLAN, ad-hoc, etc.
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Summary
Summary(2)
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Multiple description coding
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Combined with path diversity to enhance its
benefits for media streaming
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Summary
References
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J. G. Apostolopoulos, W. Tan, S. J. Wee, and G. W. Wornell. “Modeling
Path Diversity for Multiple Description Video Communication,” IEEE
ICASSP, May 2002.
R. Puri and K. Ramchandran. “Multiple Description Source Coding Using
Forward Error Correction Codes,” IEEE Asilomar Conference on Signals,
Systems, and Computers, October 1999.
J. G. Apostolopoulos, W. Tan, S. J. Wee, and G. W. Wornell. “Modeling
Path Diversity for Multiple Description Video Communication,” IEEE
ICASSP, May 2002.
L. Ozarow. “On a Source Coding Problem with Two Channels and Three
Receivers,”Bell Syst. Tech. J., 59:1909–1921, December 1980.
J. G. Apostolopoulos, T. Wong, W. Tan, and S. J. Wee. “On Multiple
Description Streaming with Content Delivery Networks,” IEEE INFOCOM,
June 2002.
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Summary
Questions and Comments?
Thank you
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Outline