Profile information in the sequence header selects one of 3 chroma formats as shown below. X represents the position of a luma (Y) pixel, O represents the position of both a Cr and a Cb pixel. Z represents co-located Y, Cr, and Cb pixels.

4:2:0 format (ATSC broadcast streams are constrained to use this format)

In this format a macroblock consists of 4 Y blocks, 1 Cr block and 1 Cb block.

X X X X X X X X

O   O   O   O

X X X X X X X X

X X X X X X X X

O   O   O   O

X X X X X X X X

4:2:2 format

In this format a macroblock consists of 4 Y blocks, 2 Cr blocks and 2 Cb blocks.

Z X Z X Z X Z X

Z X Z X Z X Z X

Z X Z X Z X Z X

Z X Z X Z X Z X

4:4:4 format

In this format a macroblock consists of 4 Y blocks, 4 Cr blocks and 4 Cb blocks.

Z Z Z Z Z Z Z Z

Z Z Z Z Z Z Z Z

Z Z Z Z Z Z Z Z

Z Z Z Z Z Z Z Z

MPEG 2 Video Compression Topics:

Introduction to MPEG 2 Video Compression

MPEG Coder/Decoder Diagram

Profiles and Levels

Frames, Fields, Pictures (I, P, B)

I P B Picture Reordering

Pixel Positioning

Compression tools

MPEG 2 Video Data Structures