Page 228 - Video Coding for Mobile Communications Efficiency, Complexity, and Resilience

Chapter 9

Error-Resilience Video

Coding Techniques

9.1 Overview

As already discussed, one of the main requirements for mobile video com-
munication is error resilience. When transmitted over a mobile channel, video
can be a ected by a number of loss mechanisms, like multipath fading, shad-
owing, and co-channel interference. The e ects of such errors are magni ed
due to the fact that the video bitstream is highly compressed to meet the
stringent bandwidth limitations. The higher the compression, the more sensi-
tive the bitstream is to errors, since in this case each bit represents a larger
amount of decoded video. The e ects of errors are also magni ed by the use
of predictive and VLC coding, which can lead to temporal and spatial error
propagation. It is therefore not di$cult to realize that when transmitted over a
mobile channel, compressed video can su er severe degradation, making the
use of error-resilience techniques vital. This chapter reviews error-resilience
video coding techniques.
The rest of the chapter is organized as follows. Section 9.2 describes the
main functional blocks of a typical video communication system. Section 9.3
highlights the main types of errors that can a ect a video bitstream. Section
9.4 examines the impact of such errors on the decoded video. Section 9.5
describes a number of error detection techniques. Sections 9.6–9.8 reviews
three main categories of error-resilience video coding techniques. The chapter
concludes with a discussion in Section 9.9.

9.2 A Typical Video Communication System

Figure 9.1 shows a typical video communication system. The encoder consists
of a source encoder and a channel encoder.

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