User Guide

MPEG Overview 307
Figure 6 shows the relative x-y locations of the luminance and chrominance components.
For every four luminance values, there are two associated chrominance values: one Cb value
and one Cr value. The location of the Cb and Cr values is the same, so only one circle is
shown in Figure 6.
There are three picture types: I, P, and B (see “Interframe Compression” on page 309).
Slice One or more contiguous macroblocks. The order of the macroblocks within a slice is
from left to right and top to bottom. Slices are important in the handling of errors. If the
bitstream contains an error, the decoder can skip to the start of the next slice. Having more
slices in the bitstream allows better error concealment, though uses bits that could
otherwise be used to improve picture quality.
Figure 6: Luminance and chrominance
= Y value = Cb, Cr value