The source pictures consist of three rectangular matrices of integers: a luminance matrix (Y) and two chrominance matrices (Cb and Cr).

The MPEG supports three formats:

**4:2:0 format**- In this format the Cb and Cr matrices shall be one half the size of the
Y matrix in both horizontal and vertical dimensions.
**4:2:2 format**- In this format the Cb and Cr matrices shall be one half the size of the
Y matrix in horizontal dimension and the same size in the vertical
dimension.
**4:4:4 format**- In this format the Cb and Cr matrices will be of the same size as the Y matrix in both vertical and horizontal dimensions.

Looking at some video capture cards (e.g. Intel's PC one) it may be hard to convert to this, but then this is targeted at digital video tape and video on demand really.