DVD Demystified

96
Figure 3.3
Block transforms and
quantization
TEAMFLY
Chapter 3
pictures, many of which are very similar, each picture can be compared with
the pictures near it. The MPEG encoding process breaks each picture into
blocks, called macroblocks, and then hunts around in neighboring pictures
for similar blocks. If a match is found, instead of storing the entire block, the
system stores a much smaller vector describing how far the block moved (or
did not move) between pictures. Vectors can be encoded in as little as 1 bit,
so backgrounds and other elements that do not change over time are com-