Source and channel coding
Digital terrestrial television - Principles

The digital video format uses 166 Mbit/s of raw bitrate to encode images before compression. At the output of the compressor, we'd like to obtain a bitrate of around 15 Mbit/s, taking advantage of the fact that there is a certain amount of redundancy both within frames and between successive frames.

MPEG-2 compression (figure 13) will be carried out on repetitive groups of images, called GOPs, which are made up of three types of image, based on the principle that one image in a sequence is generally very little different from the one that precedes it. These images are called: I (Intra), P (Predicted), B (Bidirectional). A GOP is a sequence of images between two "I" images (figure...