SDI- Serial Digital Interface Explained

SDI-Serial Digital Interface
SDI is a standard for digital video transmission commonly used in broadcasting and other professional applications. It uses a pair of coaxial cables to carry a single digital signal through optical fiber at a rate of 270 Mbps to 12 Gbps. SDI is a point-to-point interface, meaning that each cable carries a signal from one device to another. It is not intended for use in consumer applications.

SDI is used extensively in the broadcasting and professional video industries. Many high-end video cameras have an SDI output, and many broadcast facilities have extensive SDI infrastructure.

This blog post will take a closer look at the SDI standard and how it works.

What is the Serial Digital Interface(SDI)?
A serial digital interface, or SDI, is a video interface used in professional video equipment. It allows for the transmission of uncompressed, high-quality video signals between devices.

Serial Digital Interface
The SDI standard was first developed by the Society of Motion Picture & Television Engineers (SMPTE) in 1989 and has been continually updated to keep up with advancing technology. The latest version, 24G-SDI, was released in 2020.

The SDI interface uses a serial data format of analog sync (data words of 8 or 10 bits) to transmit digital video signals. It means that the data is sent one bit at a time rather than in parallel as with other video interface standards. The main benefit of this is that it allows for longer-distance transmissions without repeaters.

Key Features and Benefits of SDI signals
SDI is a type of digital video interface that uses coaxial cable to send uncompressed, high-definition video from devices like cameras to monitors or other video equipment. It’s often used in professional settings where the highest quality video is required.

Some of the features of SDI include:

Uncompressed video: SDI sends video data without any compression, resulting in a high-definition multimedia interface.
Error correction: SDI includes built-in error correction that helps to ensure that video transmission is as smooth and reliable as possible.
Low latency: SDI has low latency, meaning that there is very little delay between the time a signal is sent and the time it is received. It’s important for applications where timing is critical, such as live broadcasts.
Long-distance transmission: SDI can transmit video signals over long distances without degradation of the signal quality.
If you need a high-quality video interface for your professional applications, SDI is a great option. It provides uncompressed video, error correction, and low latency, ideal for mission-critical applications.

Electrical Interface of SDI
The electrical interface of SDI is a familiar sight to anyone who has worked in broadcast or production. It uses a standard BNC connector, and the video signal is transmitted on a coaxial cable. The cable is usually wrapped in a metal shield to protect it from interference. The signal is transmitted in the same way as composite video, but it carries a serial digital data stream. The SDI standard has been around for many years, and most professional equipment uses the interface.

Common Versions of SDI Signals
There are different versions of SDI that have been developed over the years, but they all send uncompressed signals. Some of the most common versions are as follows:

SD-SDI
SD-SDI is a type of SDI introduced in 1989 that uses two coaxial cables to send video and independent digital audio signals. It was developed to make it easier to run HD signals over long distances.

The main advantage of SD-SDI is that it can carry more data than standard SDI. It means that you can send high-definition video signals over long distances without worrying about them becoming corrupted.

SD-SDI also uses the same connector as standard SDI, so it’s easy to use with existing equipment.

Bitrates Used in SD-SDI signals:
270 Mbps
360 Mbps
143 Mbps
177 Mbps
ED-SDI
ED-SDI is a type of SDI that was introduced in 2000. It stands for Enhanced Definition-Serial Digital Interface, and it offers a higher quality image than standard SDI. This makes it ideal for high-end applications such as broadcast and post-production.

ED-SDI uses the same connector as SD-SDI, so it’s easy to use with existing equipment. It also uses 540 Mbps bit rates.

HD-SDI
This type of SDI was introduced in 1998. It stands for High Definition-Serial Digital Interface. The single-link version of the HD-SDI interface can transmit 1080i video signals and has a maximum data rate of 1.485 Gbps.

Dual-Link HD-SDI
Dual-link HD-SDI was introduced in 2002. It allows for the transmission of high-definition video signals at a data rate of 2.97 Gbps. The dual-link interface is also backward compatible with the single-link HD-SDI.

3G-SDI
3G-SDI was introduced in 2006 that can transmit and receives video and embedded audio at a data rate of up to 3 Gbps. Thi

s makes it the highest-performing SDI standard to date.

6G-SDI
In 2015, the Video Electronics Standards Association (VESA) introduced the latest SDI standard, 6G-SDI. It uses a single lane of SMPTE ST 2081 instead of SMPTE ST 424 like Dual Link HD-SDI. This allows for the transmission of video signals at a data rate of up to 6 Gbps.

12G-SDI
This standard uses four lanes of SMPTE ST 2082, allowing for the transmission of video signals at a data rate of up to 12 Gbps. This will make it the highest-performing SDI standard to date.

24G-SDI
24G-SDI is the future of SDI. It will use eight lanes of SMPTE ST 2083, allowing for the transmission of video signals at a data rate of up to 24 Gbps.

Final Thoughts
Serial digital interface (SDI) has been a modern technology around for many years. It was initially developed to be used in hostile environments, but it has since expanded into other areas of broadcast and production. SDI offers uncompressed video signals with low latency, making it ideal for mission-critical applications such as live broadcasts. Different versions of SDI have been developed over the years, but they all use the same connector and offer similar performance. The latest standard, 6G-SDI, provides a data rate of up to 6 Gbps. This makes it the highest-performing SDI standard to date. 24G-SDI is the future of SDI and will offer a data rate of up to 24 Gbps. Thanks for reading!