By PURPLELEC | 26 September 2024 | 0 Comments
What is 12G-SDI?
What is SDI?
SDI usually refers to Serial Digital Interface, which is a professional video signal transmission standard designed for lossless transmission of high-quality digital video and audio signals between broadcast-level video equipment. The SDI standard supports a variety of different resolutions and frame rates, from standard definition (SD) to high definition (HD) and even ultra-high definition (UHD) resolution.
Currently used SDI interfaces are divided into the following types based on the transmission rate:
| Standard | Name | Release Time | Bitrate | Digital Video Format |
| SMPTE 259M | SD-SDI | 1989 | 270 Mbit/s, 360 Mbit/s, 143 Mbit/s, 177 Mbit/s |
480i, 576i |
| SMPTE 344M | ED-SDI | 540 Mbit/s | 480p, 576p | |
| SMPTE 292M | HD-SDI | 1998 | 1.485 Gbit/s, 1.485/1.001 Gbit/s |
720p, 1080i |
| SMPTE 372M | Dual Link HD-SDI | 2002 | 2.970 Gbit/s, 2.970/1.001 Gbit/s |
1080p60 |
| SMPTE 424M | 3G-SDI | 2006 | 2.970 Gbit/s, 2.970/1.001 Gbit/s |
1080p60 |
| SMPTE ST-2081 | 6G-SDI | 2015 | 6 Gbit/s | 2160p30 |
| SMPTE ST-2082 | 12G-SDI | 2015 | 12 Gbit/s | 2160p60 |
What is 12G-SDI?
12G-SDI refers to 12 Gigabit Serial Digital Interface, which is an evolution of SDI technology and is designed for the transmission of Ultra High Definition (UHD) and 4K video content.12G-SDI defines a transmission rate of 12 Gbit/s, and offers eight times the bandwidth of normal HD-SDI. It can support SDI signals up to 4Kp60 resolution and higher bit rate, so it is also compatible with previous standards like HD/3G-SDI. There are three connection methods for 12G-SDI, including single-link 12G-SDI, dual-link 6G-SDI and quad-link 3G-SDI.
Most 4K professional cameras on the market use 4 BNCs to simultaneously transmit 12G-SDI signals, and so do mainstream medical endoscopes and monitors. With the development of technology some cameras have 12G-SDI output interface, such as the Sony PXW-Z280 handheld all-in-one camera, only one SDI cable that meets the 12G-SDI transmission standard can directly transmit 4Kp60 signals.
12G-SDI integrates 4 cables that transmit 3G-SDI signals into one to directly transmits 4K AV signals, so that the number of cables used for transmission is reduced, the structure is simpler, and the picture quality is more stable. But it should be noted that the higher the transmission rate of the SDI signal, the higher the requirement is for the cable and the transmission distance will also be affected. Take Purplelec 4-SDI capture card as an example, the transmission distance for 3G-SDI signals is up to 150 meters, 75 meters for 6G-SDI signals and 40m for 12G-SDI signals (these data comes from practical tests, cable quality will also lead to the difference in transmission distance).
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