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Optimal Description Bandwidth Assignment for Multiple-Description-Coded Video

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Large-Scale Multimedia Streaming

The server has a video to be streamed to a large group of users
It may use multiple unicasts, IP multicast, peer-to-peer overlay multicast
Need to effectively satisfy user bandwidth heterogeneity
Mobile streaming: 100 Kb/s
Internet streaming: 500 Kb/s
MPEG video: 1 Mb/s
HDTV: 10 Mb/s or more
2 orders of magnitude difference!

MDC: Strength and Issues

Strength:
Provides more choices of streaming rate to match user receiving bandwidths.
Descriptions are independent. More robust to network dynamic.
Issues:
Optimal description bandwidth assignment
Coding efficiency Optimal description #.

Research Setting

Consider a video stream to be accessed by a large pool of users with heterogeneous bandwidths.
Users employ a “greedy” approach to maximize their video quality.
Each user joins the descriptions so that the total bandwidth best matches the receiving bandwidth without overflowing
The server encodes the video into multiple descriptions and advertise them to the users.
It has a good picture on the user bandwidth profile it is serving.

Contribution Highlight

Problem formulation and complexity analysis
Optimization problem with coding efficiency consideration
NP-hard proof
Exact solution and threshold value
Polynomial time algorithm to match all the receiving bandwidths, when description # is no less than threshold.
An efficient heuristic: SAMBA
Virtually matches the optimum
Optimal choice for description #.

Related Work

MDC was first proposed to enhance performance of telephone system, in Bell’s Lab.
A comprehensive survey of MDC can be found in [1].
Much of previous work on MDC only focus on the error resilient techniques [2][3].
To the best of our knowledge, [4] and [5] have addressed the description bandwidth assignment in MDC.
Our work advances in
General formulation with coding efficiency consideration
Exact solution and threshold value
Study of optimal description number

Optimal Bandwidth Assignment for Multiple-Description-Coded Video

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ABSTRACT

In video streaming over multicast network, user bandwidth requirement is often heterogeneous possibly with orders of magnitude difference (say, from hundreds of kb/s for mobile devices to tens of Mb/s for high-definition TV).
Multiple descriptions coding (MDC) can be used to address this bandwidth heterogeneity issue. In MDC, the video source is encoded into multiple independent descriptions. A receiver, depending on its available bandwidth, joins different descriptions to meet their bandwidth requirements.
An important but challenging problem for MDC video multicast is how to assign bandwidth to each description in order to maximize overall user satisfaction. In this paper, we investigate this issue by formulating it as an optimization problem, with the objective to maximize user bandwidth experience by taking into account the encoding inefficiency due to MDC. We prove that the optimization problem is NP-hard.

EXISTING SYSTEM

In media streaming, the Internet’s intrinsic heterogeneity continues a challenging problem. End users may have different edge bandwidth for data receiving or forwarding, especially in large-scale streaming with hundreds of thousands of users.
Description coding rates have straightforward impact to the delivery performance. If a description has a high coding rate, some network paths may not have enough bandwidth to support its delivery. The loss rate of the description will be high. On the other hand, if descriptions have low coding rates, the number of descriptions and accordingly the coding cost will be high.

PROPOSED SYSTEM

We propose an adaptive approach to adjust description coding rates according to the user bandwidth distribution.
Our target is to provide the best streaming quality under certain network bandwidth constraint.
We formulate the problem and address it by an adaptive solution. Our results show that arbitrary description rates may severely degrade system performance and an optimal solution can make significant improvement on the use of network bandwidth.