Serial Digital Interface (SDI) is a standard for the delivery of digital video with coaxial cable.

While data speeds up to 3 gigabits per second (Gbps) are possible with SDI, the most common speed is half that at 270 Mbps. SDI uses a standard 75-ohm cable, which is the same cable used for most home television installations.

In the SDI standard, signals are uncompressed and self-synchronizing between the transmitter and the receiver. This standard utilizes data words that are typically 8 or 10 bits in length. Most SDI signals can contain up to four independent digital audio signals in addition to the video signal.  SMPTE 2110 is an emerging standard for SDI over IP networks.