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What is 6G-SDI?

Number of visits: Date:2018-5-3 17:01

Abstract:

If what you're shooting is limited to 1080p60 at the highest quality, you don't need anything better than 3G-SDI. In fact, unless you are designing a live broadcast switching environment, you don’t even have to worry about what standard you’re working with because the camera manufacturer has thought it out for you. It works great for 1080p, and with dual 3G-SDI you can transport a full 12-bit 4:4:4 or RGB 1080p60 feed with space for audio and metadata as well. You can even do 2K. But, what about 4K?


With 4K, you are probably expecting to follow that trend. To this affect, many devices have been announced (some are even available) that support a standard called 6G-SDI. It is an SDI standard that is intended to be twice as fast as 3G-SDI (2.97Gb/s), which means it's supposed to deliver a payload of 5.94Gb/s.


Notes about 6G-SDI (compared to HD-SDI, 3G-SDI, and 12G-SDI):

  • 1080p30 is the best HD-SDI can do.
  • 3G-SDI cannot do 4:4:4 1080p at 60fps.
  • 6G-SDI will breeze past every limitation in 3G-SDI. This is beneficial especially when you want to transmit stereoscopic data over a cable (though it is somewhat limited in practice because each camera will have a separate BNC connection).
  • 6G-SDI cannot do 4:4:4 4K, even at 30p – neither in 10-bit nor 12-bit. This is the biggie.
  • 6G-SDI can do 4K RAW, even at 60p – now you know why camera manufacturers are happy to give you RAW data instead of RGB or 4:4:4.
  • Even 12G-SDI or dual 6G-SDI cannot do 4:4:4 or RGB 4K at 60p! These two formats are marked in red.
  • If all you're shooting is RAW, then 6G-SDI can cover most scenarios, except 16-bit RAW (not in chart).


As the signal payload reaches 3Gb/s (in 3G-SDI), the strength of the signal drops by 40%! Fiber performs better than copper cables here, but are more expensive. The point is, you shouldn't drive a standard to its limits in normal use.


What do we learn? For one, 6G-SDI does not really help if we are looking for a scaled-up version of SDI. 4K is four-times the data rate, so we need a standard that is four times as fast as 3G-SDI. Even that (12G-SDI) cannot do 10-bit 4Kp60 in RGB.


Yet we have manufacturers (the ones who have 6G-SDI products out in the market) urging everyone to jump on the 6G-SDI bandwagon. Should you? Remember that only opt for 6G-SDI for 4K RAW data transfer. If you're not shooting RAW then it is pointless.

TypeInfo: Knowledge Center

Keywords for the information:SDI  6G-SDI  SMPTE