CCIR 601 is a standard published by the CCIR for encoding interlaced analogue video signals in digital form. It includes methods of encoding 525-line 60 Hz and 625-line 50 Hz signals, both with 720 luminance samples and 360 chrominance samples per line. Luminance sampling frequency is 13.5 MHz, giving a data rate of 165 Mbit/s. The colour encoding system is known as 4:2:2, that being the ratio of (luminance data):(blue chroma data):(red chroma data).
In each 8-bit luminance sample, the value 16 is used for black and 235 for white, to allow for overshoot and undershoot.