Digital Compression In More Detail
All commonly used digital video formats use some level of compression. Top-of-the-line digital camcorders use a "no compromise" digital 4:2:2 format, which has minimal compression, with the luma and chrominance recorded separately. This format also has a much higher digital sampling rate and requires considerable bandwidth to record.
Other camcorders use a 4:1:1 format, which depends on a greater level of compression, resulting in some minimal compromises in video quality.
Although an initial side-by-side comparison of the 4:2:2 and 4:1:1 may reveal little or no difference, the quality advantage of 4:2:2 becomes apparent when editing, copying, and complex visual effects are required.
The chart below may help in visualizing the different sampling formats. The B&W (black and white) designation shows the luma samples per given interval; the Color (chroma) designation represents the number of times the chrominance is sampled during that interval.