(1.1) This standard defines the time division multiplexing (TDM) of various standard-definition digital video and generic 8-bit data signals over high-definition serial digital interfaces (SMPTE 292M). (1.2) The objective of this high-definition multiplexing interface is to use a single physical link to transmit, distribute, route, and switch a complete family of existing 10-bit video formats and various data formats. (1.3) Active video and vertical blanking areas in the HD SDI stream are time divided into 19 interleaved channels. The word in the first channel is used to indicate the data validation of the remaining 18 channels. (1.4) A single video or data stream is multiplexed into one or multiple channels of the total 18 data channels. A control packet is multiplexed into the horizontal ancillary data space of the luminance parallel data area after the switching point of the HD stream for each video or data stream. The control packet indicates how and which channels are used for this video or data stream. It also contains stream clock reference information for clock recovery of the original clock signal. (1.5) Multiple standard definition video or data streams could be multiplexed in and demultiplexed from a single HD SDI stream with a total delay of a fraction of a horizontal line. (1.6) By dividing the payload into segments which are subdivided into channels, time-division multiplexing can be applied to several data sources in a way that very low latency will be generated during the demultiplexing process. A fixed number of channels in each segment provides an efficient implementation of different data by reducing the complexity of the multiplexing and demultiplexing processes.