Next-Generation Video Coding and Streaming

CHAPTER 2VIDEO CODING FUNDAMENTALS

Compression reduces the cost of storing and transmitting a video by converting the information to a lower bit rate. This chapter describes the main building blocks of video coding and many practical tips on improving the compression efficiency and video quality for different types of content. These fundamental principles underpin legacy as well as emerging video coding standards that support efficient video delivery and storage.

2.1 SAMPLING FORMATS OF RAW VIDEOS

Storage space and transmission bandwidth dictate the need for video compression. Unlike audio, raw or uncoded videos require massive storage space. For example, a raw 60-min SD video may require over 100 Gbytes of storage, which is roughly equivalent to 25 standard DVDs. A raw 1-min UHD-1 video may take up as much as 50 Gbytes. A raw UHD-2 video doubles the storage requirements. Each digital video frame, which may also be known as a picture or an image, is sampled and represented by a rectangular matrix or array of picture elements called pixels or pels for short. The term pixel is commonly used to describe still-frame images. If the image contains smooth surfaces (e.g., sky, grass, walls), the colors of adjacent pixels can be highly correlated (i.e., pixel correlation approaches 1).

Each raw pixel in a video frame can be separated into three samples that correspond to three different color components. They are the luminance (Y) sample and two color samples namely red chrominance ...