SDI (Serial Digital Interface) explained.
SDI has been the broadcast video standard for two decades.
Where we use this- On the production floor: camera to mixer, mixer to encoder, anything within about 100 metres.
- Uncompressed, near-zero latency, and no network to configure. It just arrives.
- 12G-SDI needs better cable and shorter runs than 3G-SDI. Beyond that, fibre.
What it means in live production.
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.
How it works on a live production.
The standard has evolved through several generations, each supporting higher resolutions and data rates:
SD-SDI
(SMPTE 259M). 270 Mbps, supporting standard definition video
HD-SDI
(SMPTE 292M). 1.485 Gbps, supporting 720p and 1080i
3G-SDI
(SMPTE 424M). 2.97 Gbps, supporting 1080p at up to 60fps
6G-SDI
(SMPTE ST 2081). 6 Gbps, supporting 2160p (4K) at 30fps
12G-SDI
(SMPTE ST 2082). 12 Gbps, supporting 2160p (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. Our senior lead served as Technical Manager on the Esports World Cup, across five arenas over three months, and the pattern there is the standard one for multi-venue shows: 3G-SDI for every camera feed inside 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.
Multi-camera production
SDI carries the camera feeds inside the room on our multi-camera productions.
Low-latency streaming
Sub-500ms glass-to-glass streaming via SRT and WebRTC. Real-time interaction for esports, auctions, trading floors, and live Q&A events.
ReadRTMP vs SRT: which live streaming protocol should you use?
RTMP and SRT are the two protocols most often used to send a live feed from a venue to a platform or control room.
ReadHLS (HTTP Live Streaming)
HLS is an adaptive streaming protocol where video is divided into small segments (typically 2-10 seconds), and a playlist file tells players where to find segments at various quality levels.
ReadNDI (Network Device Interface)
NDI is a protocol for real-time video transmission over IP networks, designed to be simpler and more flexible than SMPTE 2110 or SDI.
ReadIP-Based Broadcasting
IP-based broadcasting uses standard internet protocols (Ethernet, TCP/IP) to distribute broadcast signals instead of legacy specialised broadcast protocols (SDI, AES).
ReadQuestions people ask about this.
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. On multi-venue events, fibre carries every connection between venues.
Tell us the date, the venue and who is watching.
We scope every live production against its run of show, not a package.
CBA low latency streaming covers every show it produces, because transport decides whether the picture holds.