Serial Digital Interface
Serial Digital Interface (SDI), standardized in ITU-R 656, is a digitized video format used for broadcast grade video. It typically uses 75 Ohm BNC coaxial cables (which makes it easily upgradeable from analog video setups, which use the same cables). The allowed cable length is up to 250 meters.
Uncompressed digital component or digital composite signals can be used. The SDI signal is self-synchronizing, uses 8 bit or 10 bit data words, and has a maximum data rate of 270 Mbit/s, with a minimum bandwidth of 135 MHz.
A SDI signal may also contain up to four embedded AES/EBU audio channels in the auxiliary data fields.
There is an expanded specification called SDTI (Serial Digital Transport Interface), which allows compressed (i.e. DV, MPEG and others) video streams to be transported over a SDI line. This allows for multiple video streams in one cable or faster-than-realtime (2x, 4x,...) video transmission.
