SDI stands for “serial digital interface",HD-SDI is a new technology offering full High Definition 1080p picture over coaxial cable, 
SDI is a standard used for the transmission of digital video signals over a coaxial cable,be run long distances without video loss,

It can offer real-time and un-compressed broadcasting video quality, up to 1080p / 2.2 MP resolution.SDI technology has been in 

existence in the media TV market,It is simple Plug and Play installation.