TITRE Adaptive Packet Video Streaming Over IP Networks - LaBRI

Chapter 2
2 Introduction
2.1 Motivation
The rollout of Internet opens up a new frontier for the digital video broadcasting industry.
Two worlds that were barely connected are on the verge of being merged: namely, real-time video
and Internet. Thanks to the transition of the video medium from analog to digital, and the rise of
powerful video compression techniques, such as H.264 and MPEG-4, it is now possible to
combine video, audio, and data within the same signal and transmit it over an multi-service packet
switching network infrastructure, such as the Internet.
These advances will lead to the emergence of new powerful multimedia applications, with
limitless possibilities of great commercial potential. For example, computers can be turned into
traditional TV receivers and the digital set-top boxes can host applications such as interactive TV,
e-commerce, and customized programming.
Using the Internetworking Protocol (IP) as a medium for the transmission of real-time
multimedia applications is a challenging problem. These applications require real-time performance
guarantee in term of bounded transfer delay and jitter, low packet loss, and bandwidth guarantee.
IP is a best effort packet switching technology. It does not guarantee itself any Quality of Service
(QoS) such as transfer delay, jitter, loss, and bandwidth. These performance metrics are affected by
many parameters, some of them are related to the end systems (e.g. video server load) and others
are related to the network (e.g. link capacity, router buffer, etc.). The provision of quality of service
for IP has been the subject of significant research and development efforts recently. Two
approaches have drained the attention of the IETF: namely the Integrated Service (Intserv) and the
Differentiated Service (Diffserv) architectures. The key difference between Intserv and Diffserv is
that while Intserv provides end-to-end deterministic QoS service on a per-flow basis, Diffserv is
intended to provide better scalability through flow aggregation, class differentiation and statistical
QoS guarantee over a long timescale.
In this thesis, we study the problems involved in the transport of real-time video streams over
IP Differentiated Service networks. We fellow a cross-layer approach for resolving some of the
critical issues on delivering packet video data over IP networks with satisfactory quality of service.
While, current and past works on this topic respect the protocol layer isolation paradigm, the key
idea behind our work is to break this limitation and to rather inject content-level semantic and
service-level requirements within the proposed IP video transport mechanisms and protocols.
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