Serial digital interface [SDI] standard is based on a 270 Mbps transfer rate, over a single 75 ohm coaxial cable [BNC connector], up to 600 feet. Serial Digital Interface is a [standard definition] digital broadcast television standard providing a lossless digital encoding of standard NTSC and PAL formats [with embedded audio]. SDI is used in Television stations, cable channels, and professional production Equipment. SDI provides a method for transmitting uncompressed digital video, audio and other data between video devices.
SDI is described in ITU R BT 601 standard for interface of component digital video. SDI is defined in SMPTE259M and ITU-R BT.656 standards. SMPTE259M defines four standard bit rates from 143Mbps to 360Mbps [ 270Mps is common]. SMPTE 344M adds a 540Mbps bit rate. One component of luminance (with 720 samples per line), and two of color (each with 360 samples per line). There are either 10 or 8 bits per sample [scrambled, polarity independent interface, with common scrambling for both component ITU-R 601 and composite digital video and four channels of (embedded) digital audio]. The SDI bit stream is encoded using a pseudo-random scramble followed by a a NRZ-to NRZI conversion. The scramble code is x⁹+ x⁴+1. The original 8-bit SDI format was based on CCIR-601, the new 10-bit version is called SDTI [Serial Digital Transport Interface.
Serial digital data interface (SDDI) is a way of compressing digital video for use on SDI-based equipment from Sony.
SDDI is now incorporated into Serial digital transport interface.

NTSC [National Television System Committee] is used in US [and Japan]
PAL [Phase Alternation by Line] is used outside the US
.... M-PAL [Phase Alternation by Line] is used outside the US [Brazil]
.... N-PAL [Phase Alternation by Line] is used outside the US
SECAM [Sequential Color with Memory] is used outside the US [France/Russia/Africa]