4. Source and channel coding

4.1 Principle of MPEG-2 video compression

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...