SDI (Serial Digital Interface)
SDI (Serial Digital Interface) is the standard method for transporting uncompressed digital video over coaxial or fibre cable in broadcast production. For over 30 years, SDI has been the backbone of live production—carrying video signals from cameras to vision mixers, replay servers, monitoring systems, and encoding equipment.
SDI is a point-to-point connection. One cable carries one signal from one source to one destination. If you need a camera feed going to a vision mixer, a replay server, and a graphics system simultaneously, you need a routing matrix to split and direct the signal. This is fundamentally different from IP-based broadcasting where signals travel over network switches and can be multicast to many destinations.
The standard has evolved through several generations, each supporting higher resolutions and data rates. SD-SDI (SMPTE 259M) runs at 270 Mbps for standard definition. HD-SDI (SMPTE 292M) pushes 1.485 Gbps for 720p and 1080i. 3G-SDI (SMPTE 424M) reaches 2.97 Gbps for 1080p at up to 60fps. 6G-SDI (SMPTE ST 2081) delivers 6 Gbps for 4K at 30fps, and 12G-SDI (SMPTE ST 2082) hits 12 Gbps for 4K at 60fps. Each step up requires either new cabling or infrastructure that supports the higher data rate.
HD-BNC connectors are standard on modern broadcast equipment like the Evertz XPS encoder and DreamCatcher replay systems. At Creative Broadcast Agency, SDI remains our primary signal format for camera runs and short-distance connections within venues.
For the Esports World Cup, we used 3G-SDI for all camera feeds within each arena, with SRT for contribution between arenas and the MCR. The reliability of SDI over short distances is unmatched—there is no network configuration, no IP addressing, no packet loss. You plug in a cable and the signal arrives.
The transition from SDI to SMPTE 2110 is happening in larger facilities, but SDI is far from obsolete. Most professional cameras, vision mixers, and monitoring equipment still use SDI as their primary interface. Hybrid workflows—SDI within the production area, IP for distribution and contribution—are the practical reality for most productions today.
Frequently Asked Questions
Is SDI being replaced by IP?
Gradually, in large facilities. SMPTE 2110 offers scalability advantages for facilities with 12+ camera feeds and complex routing. But SDI remains the standard for camera-to-mixer connections, OB truck production, and smaller installations. Most productions use SDI and IP together rather than choosing one exclusively.
What cable do I need for SDI?
75-ohm coaxial cable (Belden 1694A or equivalent) for runs up to 100 metres at 3G-SDI. For longer distances, fibre optic SDI transport extends the range significantly. 12G-SDI requires higher-quality cable or fibre for reliable signal at full bandwidth.
Can I convert SDI to IP and vice versa?
Yes. Gateways and encoders like the Evertz XPS accept SDI input and output IP streams (SRT, SMPTE 2110, RTMP). Decoders do the reverse. This is how hybrid SDI/IP workflows operate—SDI on the production floor, IP for distribution.
What is the maximum cable length for SDI?
Approximately 100 metres for 3G-SDI on quality coaxial cable, shorter for 12G-SDI (around 50–80 metres). Beyond these distances, you need fibre optic transport or SDI-over-fibre converters. For the Esports World Cup, we used fibre for all inter-arena connections.
Need help with SDI & broadcast infrastructure?
Creative Broadcast Agency designs and deploys SDI and hybrid SDI/IP workflows for live productions of any scale.