4:2:0

Same bandwidth at double the horizontal sampling rate of 4:1:1, with trade-off being that the two chroma channels (Cb and Cr) channels are only sampled on each alternate line, so vertical resolution is effectively halved. Used for MPEG-2 Part 2 and MPEG-2 Part 4 (H.264) although some high profiles allow for 4:4:4.