What’s Serial Digital Interface (SDI) ?

Posted on by Eugene Bocharov

Serial digital interface (SDI) is a family of digital video interfaces first standardized by SMPTE (The Society of Motion Picture and Television Engineers) in 1989. Today, an uncompressed, full bandwidth signal that can be carried on just one wire. Even though it is now being used as the signal of choice for high definition TV, its roots go back many years to standard definition, or SD video. Today, we have many flavors of SDI that differ primarily in their serial data rate and the resolution of the video signal they carry.

SDI takes this even further by supporting, in addition to the video, the capability to transport up to 16 channels of audio (either digital AES or analog converted to AES), metadata about the video content itself and other ancillary data. All this is done in a defined, non-proprietary manner according to a suite of SMPTE standards which include using SDI standards to transport compressed video standards and even 3D-TV. The implications of this are vast. One signal can now be used for transporting video and audio saving on cable costs. Technically, the audio and video can remain in lip-sync as long as they are transported together throughout the distribution network.

Canare 50 ft HD-SDI Video Coaxial Cable (Blue)

Standard Name Introduced Bitrates Example video formats
SMPTE 259M SD-SDI 1989 270 Mbit/s, 360 Mbit/s, 143 Mbit/s, and 177 Mbit/s 480i, 576i
SMPTE 344M ED-SDI 540 Mbit/s 480p, 576p
SMPTE 292M HD-SDI 1998 1.485 Gbit/s, and 1.485/1.001 Gbit/s 720p, 1080i
SMPTE 372M Dual Link HD-SDI 2002 2.970 Gbit/s, and 2.970/1.001 Gbit/s 1080p
SMPTE 424M 3G-SDI 2006 2.970 Gbit/s, and 2.970/1.001 Gbit/s 1080p
SMPTE ST-2081* 6G UHD-SDI 6 Gbit/s 4Kp30
SMPTE ST-2082* 12G UHD-SDI 12 Gbit/s 4Kp60

 

 

3G/HD/SD-SDI Extenders

BZB Express offers a wide variety brands for extending 3G-SDI, HD-SDI and SDI signals. The most economical way of extending an SDI signal is using a cable equalizer, which will transmit an HD-SDI 400 feet and an SDI, signal 500 feet. For extreme SDI extension, the use of fiber optic transmitters and receivers will carry a 3G-SDI, HD-SDI and SDI signals up to 30 km or 18.75 miles. SDI extenders can be found in applications such as live staging or postproduction, studio work and other broadcasting type environments.

 

SDI Amplifier & Splitters:

SDI Distribution Amplifiers and splitters allows a single or multiple SDI, HD-SDI or 3G-SDI video source to be distributed to (without loss of signal) four HD SDI/HDSDI/3GSDI devices at the same time. Crisp, highly defined visuals are generated in NTSC or PAL format.

SDI Switcher

SDI Switchers allow SDI signals to switch from one source to another whether you have 2, 4, 8 or more SDI signals. SDI switchers are mainly used in broadcasting applications such as studio work, live staging or postproduction. These types of switchers may be as simple as a 4×1 I/O, fixed I/O matrix switchers, modular solutions or even as a seamless switcher with PIP (picture in picture) feature. Many of these SDI switchers support audio, but if you are only looking for video that option is available.

SDI Converters and Scalers

Serial Digital Interface, better known as SDI is part of the family of digital video interfaces. The purpose of SDI converters is to either convert SDI to a different standard such as HDMI, DVI, component and composite or vice versa. There are many types of SDI converters depending on your application. SDI Converters are typically used in broadcasting environments, studio work, live staging and post production.

One thought on “What’s Serial Digital Interface (SDI) ?”

  1. In addition to the regular serial digital interface described here, there are several other similar interfaces which are similar to, or are contained within, a serial digital interface.

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