Macroblock is a term used in video compression, which represents a block of 16 by 16 pixels. Each macroblock contains 4 Y block, 1 Cb block, 1 Cr block (4:2:0). (It also could be represented by 4:2:2 or 4:4:4 YCbCr format). Macroblocks can be subdivided further into smaller blocks, called partitions. H.264, for example, supports block sizes as small as 4x4.

Macroblocking

This is a non-technical term used when macroblocks are missing and show up as video errors. Square areas of the picture do not show the correct portion of the image, but instead show a single color block. Advanced decoders hide these types of errors with a technique called error concealment.

Macroblock coding

ADDR .... address of block in image

TYPE .... identifies type of macroblock (intra-frame, inter frame, bi-directional inter frame)

QUANT ... quantization value to vary quantization

VECTOR... motion vector

CBP...... Coded Block Pattern, some blocks in macroblock match well, some match poorly - this is bit mask signifying which one is present.

the blocks (4 Y, 1 Cr, 1 Cb)