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The Definition of SDI Standards: SDI, HD-SDI, 3G-SDI, 6G-SDI, 12G-SDI and 24G-SDI

Number of visits: Date:2018-5-3 15:58


Serial Digital Interface (SDI) is a family of digital video interfaces first standardized by SMPTE (Society of Motion Picture and Television Engineers) in 1989. For example, ITU-R BT.656 and SMPTE 259M are defined for broadcast-grade video. The SDI interface is widely used in SDI encoders, SDI converters and other equipment. It has been applied to radio and television fields, security monitoring. At the same time, it has also promoted an era of a new digitized video display in both monitoring and radio and television fields. And we have witnessed the development of the video standard with the Ultra High Definition (UHD) standard from SD-SDI, HD-SDI to 3G-SDI, 6G-SDI, 12G-SDI and 24G-SDI.


The SD-SDI standard supports the 270Mb/s bit rate. SD-SDI is used to transmit low-resolution PAL compatible video 720*576 @25fps and uses a clock rate of 27MHz. In 1994, ITU-R (formerly International Radio Consultative Committee) released Recommendation BT.656-2, incorporating the new serial digital interface defined in EBU Tech.3267 and SMPTE 259M, which uses 10-bit transmission and Non-Zero Reverse (NRZI) encoding. The clock rate was 270Mb/s when transmitting a 4: 2: 2 level signal from ITU-R BT. 601 (part A), at which point the SD-SDI standard was defined, which is today’s SDI.


The HD Serial Digital Interface (HD-SDI) standard is standardized in SMPTE 292M. Although this standard is known as the 1.5Gb/s interface, the bit rates supported by HD-SDI are actually 1.485Gb/s.


The 3G-SDI standard is known as the 3Gb/s interface, but the actual bit rates are 2.97Gb/s. 3G-SDI supports several different mapping levels, as described in the SMPTE ST425-1 standard. These levels are called A, B-DL, and B-DS. Like the HD-SDI standard, the 3G-SDI supports 3G-SDI CRC generation and checking as well as line number insertion and capture.


This 6G-SDI standard, standardized in SMPTE ST-2081, defines a bit-serial data structure, electrical signal and coaxial cable interface for the transport of signals with a total payload of 5.94Gb/s. This standard also specifies the electrical and physical characteristics of coaxial cables and connectors. This standard defines several mapping modes for the carriage 2160-line and 1080-line image formats and associated ancillary data into a single-link 6Gb/s (nominal) SDI bit-serial interface.


The 12G-SDI standard, standardized in SMPTE ST-2082, is developed to support higher resolution, frame rate, and color fidelity. It provides four times the bandwidth of HD, carrying 12Gb/s, making it ideal for the 4K 60p format. This is not new, UG has been developed 6G/12G since 2012, but has not been approved by the standard governing body SMPTE under the SMPTE ST-2082 draft name.


The 24G-SDI standard is also known as UHD-2 or 24G UHD-SDI. Defined in SMPTE ST-2083, this standard supports 4K 120p and 8K 60p resolution.

TypeInfo: Knowledge Center

Keywords for the information:SDI  HD-SDI  3G-SDI  6G-SDI  12G-SDI  24G-SDI