What Are Differences Between Various SDI?


SDI stands for Serial Digital Interface and refers to a group of digital video interfaces. The Society of Motion Picture and Television Engineers (SMPTE) initially formalized it in 1989. The standard has been primarily embraced by the worldwide broadcasting field and is utilized in TV studios and buildings to deliver uncompressed, unencrypted digital video signals.


SDI is also a widely used technology in the live event field, thanks to its durable connector and signal distribution lengths. The SDI standard has evolved along with the world. More SDI editions have been created to handle ever-increasing resolutions (HD, UHD, 4K, and 8K), larger bitrates, and richer colors. If you want to acquire high-quality HD and UHD PTZ camera solutions, check out the webcam & ptz camera factory Telycam.

History Of SDI Signals

SDI Signals
Source: Unsplash

The SMPTE created the SDI professional video standard in 1989. After that, six new SDI standards have been released and another one is in the making process. Here is a brief timeline of the history of various SDI signals. 


1989: SDI (Standard Definition Interface) was announced in 1989. SD SDI is an SMPTE 259M standard for delivering and obtaining video with embedded sound at data rates ranging from 177 to 270 Mbps.


1998: In 1998, High Definition SDI (HD SDI) was launched. HD SDI is an SMPTE 292M standard for 1.5 Gbps video and integrated audio transmission and reception.


2000: In the year 2000, Enhanced Definition SDI (ED SDI) was inaugurated. ED SDI is an SMPTE 344M standard that uses a 540 Mbps data rate to send and obtain video and integrated audio.


2002: In 2002, Dual Link HD SDI was published. Dual Link HD SDI is an SMPTE 372M standard for delivering and obtaining video and integrated audio at a combined data rate of 3 Gbps across two 1.5 Gbps lines.


2006: In 2006, 3 Gbps SDI was released. 3G SDI is an SMPTE 424M standard that uses a 3 Gbps data rate to send and receive video and integrated audio.


2015: SDI at 6 Gbps was first announced in 2015. 6G SDI is an SMPTE ST 2081 standard that utilizes a 6 Gbps data rate to send and obtain video and integrated audio.


2015: Again in 2015, a 12 Gbps SDI was brought in. 12G SDI is an SMPTE ST 2082 standard that employs a data rate of 12 Gbps to deliver and collect video and integrated audio. 


2020: The latest edition of 24G SDI was released in 2020. It transmits the video and audio at a bit rate of 24 Gbps. 

Different Types Of SDI Signals

As we said, SDI is a group of digital video interfaces, which are classified as SDI, HD SDI, 3G SDI, 6G SDI and 12G SDI, and 24G SDI.

What Is SDI

The SMPTE group created the SDI (Serial Digital Interface) digital video interface standard. This serial interface uses one channel to send all bits of the data word and its related data. Serial digital signals must be handled before transmission because of their high data rate.


SDI is a digital video transmission technology that is widely utilized in broadcasting, live events, and other professional settings. It employs two coaxial cords to transmit one digital signal via optical fiber at speeds ranging from 270 Mbps to 12 Gbps. The ptz sdi is a point-to-point interface, which implies that every wire transports data from one appliance to another.

What Is SD SDI

The 270 Mb/s data rate is supported by the SD SDI standard. SD SDI employs a clock rate of 27 MHz to deliver low-resolution PAL video at 25 frames per second. In 1994, the ITU-R issued Recommendation BT.656-2, which included the new serial digital interface distinguished in EBU Tech.3267 and SMPTE 259M. It uses non-Zero Reverse (NRZI) encoding and employs 10-bit transmission. It is mainly utilized for 480i and 576i video formats.

What Is HD SDI

SMPTE 292M defines the HD Serial Digital Interface (HD SDI). Even though this standard is referred to as the 1.5 Gbps interface, the data rates endorsed by HD SDI are actually 1.485 Gbps and 1.485 / 1.001 Gbps. The hd sdi ptz is especially employed for 720p and 1080i video formats. 

What Is 3G SDI

Although this interface is referred to as a 3 Gbps interface, the real bit rates are 2.97 Gbps and 2.97 / 1.001 Gbps. According to the SMPTE ST425-1 standard, 3G SDI allows numerous different mapping levels, which are known as A, B-DL, and B-DS. The 3G SDI standard allows 3G SDI CRC generation and validation and line number insertion and capture. It is mostly in use for 1080p video format.

What Is 6G SDI

For carrying the signals with an entire payload of 5.940 Gbps or 5.940/1.001 Gbps, this standard provides a bit-serial data pattern, electrical signal, and coaxial cord interface. The electrical and physical features of coaxial cables and connectors are also defined in this standard. This standard illustrates various mapping methods for transferring 2160-line and 1080-line picture formats. It is largely utilized for 1080p and 2160p video formats at 60 frames per second and 30 FPS.

What Is 12G SDI

The 12G SDI is a high-resolution, enhanced frame-rate, and high-color commitment SDI standard. It has four times the capacity of HD and can send 12 Gbps, which makes it perfect for 4K 60p. It is especially utilized for 2160p video formats at 60 FPS.

What Is 24G SDI

The latest generation of SDI, 24G SDI, is the future. This standard is commonly known as UHD 2 or 24G UHD SDI. It is described in SMPTE ST-2083 and supports a resolution of 8k 120p. It will utilize eight lines of SMPTE ST 2083, which will enable video signals to be transmitted at up to 24 Gbps. There are several ptz camera manufacturer companies that use 24G-SDI. 


You can scroll down further to know the differences between 3G vs 6G SDI, 3G SDI vs 12G SDI, and more. Here is a brief comparison table of various SDI:

Cable Type Launched Year Bitrates Video Format
SD SDI 1989 270 Mbps, 360 Gbps, 143 Gbps, and 177 Gbps 480i, 576i
HD HDI 1998 1.485 Gbps, and 1.485/1.001 Gbps 480p, 576p
3G SDI 2006 2.970 Gbps, and 2.970/1.001 Gbps 1080p60
6G SDI 2015 6 Gbps 2160p30
12G SDI 2015 12 Gbps 2160p60
24G SDI 2020 24 Gbps 2160p/4k@120, 8k@60

What Is The Difference Between 3G SDI vs 6G SDI vs 12G SDI?

Take a look at this SDI 3G vs 6G vs 12G comparison to know the fundamental differences between them:

SDI system for camera
Source: Unsplash


3G-SDI System These high-definition video systems are frequently established in problematic locations with a wide range of temperatures, strong vibrations, varying cable run lengths, and electrical disturbance. 3G SDI systems are critical for several applications in ship boards, aerospace, ground vehicles, and surveillance systems.

6G-SDI System The several applications of 6G SDI include supporting 4K digital cinema and ultra-high definition (UHD) television. The webcam suppliers also use 6G SDI systems.

12G-SDI System 12G products are available from a variety of sellers and can be found in converters, film cameras, production switchers, and a rising number of PCIe cards.


3G-SDI System
1. In a comparison of 12G SDI vs 3G SDI, 3G can transfer a variety of video broadcast, production, and digital film formats down the same cable.

6G-SDI System
1. Convenient Installation with only a single cord
2. Gives high-quality signal transmission with excellent quality 4K

12G-SDI System
1. In 3G SDI vs 6G SDI vs 12G SDI, 12G lessens the system complexity in a 4K pattern.
2. It is adaptable and has the potential to handle input and output (bidirectional SDI interface).



All the digits in the 3G vs 12G SDI, 6G vs 12G vs 3G SDI correspond to video bitrates

What Is The Difference Between SDI vs 3G SDI vs HD-SDI?

Online Education
Source: Unsplash

Here is a brief comparison of the differences between 3G SDI vs HD SDI: 


HD SDI optical terminal appliances are designed and manufactured for serial digital optical transmission devices with increased reliability and performance in the television field. Meanwhile, the 3G SDI digital video optical terminal equipment is an enhanced edition of HD SDI.


HD-SDI signal formats range from 19.4 Mbps to 1.485 Gbps. 3G SDI signal formats vary from 19.4 Mbps to 2.97 Gbps. HD SDI is the common name for the 1.485Gbps serial interface. SMPTE adopts SMPTE424M, a new standard that increases the SDI data rate two times to 2.97 Gbps, which is 3 Gbps (3G) SDI.

What Is The Difference Between SD SDI vs HD-SDI?

HD SDI has a significantly increased transmission data rate than SD SDI. As the luminance sampling regularity of HD video signals is 74.25 MHz, and the sampling frequency of dual-color difference signals is 37.125 MHz, the fundamental bit rate of HD-SDI is 1.485 Gbps.


The cable length will be substantially lessened when the dispersion of high-frequency transmission cord parameters influences the dispatch of HD video signals. Thus, the wire length is another distinction between SD SDI and HD SDI. 

What Is The Difference Between SDI and HDMI

SDI PTZ camera
Source: Telycam

The major differences between SDI and HDMI are video output connections and the expense to execute them. 


HDMI is used to link Blu-ray players, ptz streaming camera devices, and video gaming tools to TV in consumer-grade appliances. Whereas, SDI is more commonly used by broadcast images and engineers in professional contexts.


In several circumstances, an HDMI cord cannot be expanded beyond 50 feet without the use of an auxiliary device to boost the signal. However, SDI allows for much longer transmission distances, up to 100 feet over coax and 1,000 feet for optical fiber.


Despite the fact that HDMI may technically send high-fidelity video data, SDI is still utilized by experts since the necessary video equipment connectors are natively SDI. BNC (Bayonet Neill-Concelman) connections are used for SDI over coax.


Since several years, serial digital interface (SDI) has been a cutting-edge technology. It was created with the intention of being utilized in harsh circumstances, but it has subsequently spread into different regions of transmission and production. With time, other SDI variants have been developed, but they utilize a similar connector and provide identical performance. 


In short, SDI is a wonderful alternative if you require a high-quality video interface for skilled applications. In addition to that, SDI is suited for mission-critical applications since it provides uncompressed video, mistake correction, and less latency.

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