An ITU-R standard for component digital video (YCbCr). It was designed to provide a common digital standard for conversion from the three analog video/TV systems (NTSC, PAL/SECAM). Rec. 601 (ITU-R BT.601) also enables easy conversion back to any of the three analog signals for distribution. The choice of a luma sampling frequency of 13.5 MHz and a chroma frequency of 6.75MHz (4:2:2) yields 720 samples of active data per line for both NTSC and PAL/SECAM. For ITU-R high-definition specifications, see ITU-R HD standards. See YUV, YCbCr and chroma subsampling.