本标准描述了一种位并行复合视频数字接口，用于根据SMPTE 170M所述的525线59.94-Hz NTSC标准运行的系统，该标准以四倍的彩色副载波频率采样。定义了编码视频信号数字表示的采样参数、采样相位和颜色子载波之间的关系以及视频信号的数字电平。本标准适用于距离不超过50米的传统设计的屏蔽双绞线12对电缆，无需传输均衡或接收器的任何特殊均衡。可以使用更长的电缆长度，但在电缆选择和可能的接收器均衡或使用有源中继器或两者的同时，对谨慎性的要求迅速增加。本标准定义的数字复合视频信号是通过串行数字接口的复合实现传输的信号。 应注意的是，除本标准所述信息外，串行数字接口还包含其他信息。当电缆长度超过50 m时，串行数字接口是复合数字设备互连的首选方法。

This standard describes a bit-parallel composite video digital interface for systems operating according to the 525-line, 59.94-Hz NTSC standard, as described by SMPTE 170M, sampled at four times color subcarrier frequency. Sampling parameters for the digital representation of encoded video signals, the relationship between sampling phase and color subcarrier, and the digital levels of the video signal are defined.This standard has application for use with shielded twisted 12-pair cable of conventional design over distances up to 50 m, without transmission equalization or any special equalization of the receiver. Longer cable lengths may be used, but with rapidly increasing requirement for care in the cable selection and possible receiver equalization or the use of active repeaters or both. Digital composite video signals, as defined by this standard, are the signals conveyed by the composite implementation of the serial digital interface. It should be noted that additional information to that described by this standard is also carried by the serial digital interface.The serial digital interface is the preferred method for the interconnection of composite digital equipments when cable lengths exceed 50 m.