BNC vs SDI at DVinfo.net

Adam Letch · November 7th, 2007, 04:04 PM

hey guys,

is there a need to get a dedicated SDI cable, or is it simply that SDI cables are BNC's, but of a higher quality? And therefore can you get a BNC cable to feed video to a live feed for a event?

Thanks

Adam

Giroud Francois · November 7th, 2007, 05:35 PM

you mix two things that are totally different.
BNC is a plug format, SDI is a signal transport format.
Since SDI usually uses coaxial cable that use most of time BNC plug, you can say there is remote link between the two, but that is all.
Composite video is usually transported by coaxial cable too, and again coxial goes well together with BNC (but composite video often use CINCH plug).
So, if you need to transport video, coaxial cable is a good choice should it be in SDI format or any other format.
SDI is a digital format, so it is not a video format. It means you need to decode SDI to display the video it contains. it is pretty expensive.
composite video on the other hand is video, so any basic monitor will be able to display, while this signal has some weakness regarding quality.
You could imagine to transport video into an SDI signal and output it as composite video, but that would be silly.

Greg Boston · November 7th, 2007, 06:26 PM

Quote:

Originally Posted by Adam Letch

hey guys,

is there a need to get a dedicated SDI cable, or is it simply that SDI cables are BNC's, but of a higher quality? And therefore can you get a BNC cable to feed video to a live feed for a event?

You need good quality cable with BNC connectors that is meant for SDI work. Moreso if using HDSDI due to the data rates involved. Resistance per foot and inter conductor capacitance per foot will contribute to signal degradation without using the proper cable.

-gb-

Adam Letch · November 7th, 2007, 06:48 PM

So many things to learn in this trade, I saw two items on BHPhoto which got me asking. Appreciate your time and response.

Regards

Adam

Adam Letch · November 7th, 2007, 06:50 PM

I was under the impression that SDI was good for 200ft? Do they have signal boosters like with networking that you can have in the chain, I suppose if they exist they would induce to much noise?

Regards

Adam

November 7th, 2007, 04:04 PM	#1
Adam Letch Major Player Join Date: Feb 2006 Location: Perth, Western Australia Posts: 414	BNC vs SDI hey guys, is there a need to get a dedicated SDI cable, or is it simply that SDI cables are BNC's, but of a higher quality? And therefore can you get a BNC cable to feed video to a live feed for a event? Thanks Adam

November 7th, 2007, 06:48 PM	#4
Adam Letch Major Player Join Date: Feb 2006 Location: Perth, Western Australia Posts: 414	thanks Giroud So many things to learn in this trade, I saw two items on BHPhoto which got me asking. Appreciate your time and response. Regards Adam

November 7th, 2007, 06:50 PM	#5
Adam Letch Major Player Join Date: Feb 2006 Location: Perth, Western Australia Posts: 414	Thanks Greg I was under the impression that SDI was good for 200ft? Do they have signal boosters like with networking that you can have in the chain, I suppose if they exist they would induce to much noise? Regards Adam

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November 7th, 2007, 05:35 PM	#2
Giroud Francois Inner Circle Join Date: Feb 2004 Location: switzerland Posts: 2,133	you mix two things that are totally different. BNC is a plug format, SDI is a signal transport format. Since SDI usually uses coaxial cable that use most of time BNC plug, you can say there is remote link between the two, but that is all. Composite video is usually transported by coaxial cable too, and again coxial goes well together with BNC (but composite video often use CINCH plug). So, if you need to transport video, coaxial cable is a good choice should it be in SDI format or any other format. SDI is a digital format, so it is not a video format. It means you need to decode SDI to display the video it contains. it is pretty expensive. composite video on the other hand is video, so any basic monitor will be able to display, while this signal has some weakness regarding quality. You could imagine to transport video into an SDI signal and output it as composite video, but that would be silly.