Visual Media Coding and Transmission

5.1 Introduction

The definition of video coding standards is of the utmost importance because it guarantees that video coding equipment from different manufacturers will be able to interoperate. However, the definition of a standard also represents a significant constraint for manufacturers because it in some way limits what they can do. Therefore, in order to minimize the restrictions imposed on manufacturers, only tools that are essential for interoperability are typically specified in the standard – the normative tools. The remaining tools, which are not standardized, but are also important in video coding systems, are referred to as non-normative tools, and this is where competition and evolution of the technology will take place. In fact, this strategy of specifying only the bare minimum that will guarantee interoperability ensures that the latest developments in the area of non-normative tools will be easily incorporated in video codecs without compromising their standard compatibility, even after the standard has been finalized. In addition, this strategy also makes it possible for manufacturers to compete against each other and distinguish between their products available in the market.

A significant amount of research effort is being devoted to the development of non-normative video coding tools, with the target of improving the performance of standard video codecs. In particular, due to their importance, rate control and error-resilience non-normative tools are being ...