SDI distribution vs. HDBaseT distribution

Hi, everyone. I'm designing an upgrade to the live video system in our building from SD to HD, and I need some help picking the right components. As inputs, we will have a laptop plus a 1080p PTZ camera (Sony SRG-300H). The output is to be displayed on HDTVs in differents areas on the same floor, mostly between 50 and 150 feet away. We do not need to distribute sound to these TVs.

Currently the TVs are connected via coax and F connectors; I don't know the exact specs of the coax cable and the only marking I could see on it was "FT4 swept to 2200 MHz", so I guess it's RG6. We have a suspended ceiling, so we can replace the cabling with better quality RG6 or with Cat5e/6, as needed.

During our upgrade, we want to add Picture in Picture functionality, so I'm considering the ATEM 1 M/E Production Studio 4K.

I have two questions:

1) Considering that our inputs and display units are all HDMI, would it be better to use HDBaseT distribution (over Cat5e/6) or would it be fine to use the existing coax cabling and convert it to 3G-SDI? With HDBaseT, we would need a HDBaseT distribution amplifier and then receivers at each TV. With SDI, we would need an SDI splitter/distribution amplifier and then SDI-to-HDMI converters at each TV.

HDBaseT distribution:


SDI (i.e., 3G-SDI) distribution:


HDBaseT is supposed to have "zero" latency, and the SDI to HDMI converters may add 1 frame delay...so would the total delay for the HDBaseT option be 2 frames, vs. a delay of 3 frames for SDI option? I think a 3 frame delay would be tolerable for our use.

(I know a camera with HD-SDI/3G-SDI output would be preferable, but I don't have the budget for that. The price I've been quoted on the SRG-300H is about $2500.)

2) Instead of PiP, we would also be okay with the laptop output distributed to some TVs and the camera output distributed to the other TVs. But sometimes the camera output needs to go to all TVs and sometimes the laptop output needs to go to all TVs. So we would need a 2x2 matrix switcher, at the very least. Is there a matrix switcher, either from Blackmagic or anyone else, that is reasonably priced and can perform this switching operation smoothly and instantly. In other words, we can't have a second or two of a blank screen when switching inputs. Either HDMI or SDI would be fine, I think.

This would be the SDI version of that:


I would appreciate any input on the layouts I've described. Thanks.

I'd go with the HDBaseT distribution model for three reasons:

1. The coax that is already there, is probably not good enough for 3G-SDI (depending on the lengths, of course).
2. Coaxial cable is expensive, compared to CAT5E / CAT6. (Although make sure you get some high-quality CAT6 with low / no skew for the best result).
3. SDI equipment is more or less "locked" to broadcast standards. You may want to use higher, or non-conventional resolutions later.

F-connector sounds like antenna ....

Do you really know, what kind of sd-signals are transmitted ? Maybe it's a CCTV-system ? Does someone know a HD-RF-modulator for use in CCTV private networks ? I found these :

http://www.alibaba.com/product-gs/14658 ... r.html?s=p
http://www.pvistore.com/4-hdmi-rack-rf-modulator/

Thanks for the replies.

I've looked at those QAM modulators before, and the latency would be too high I think. In one of their product brochures, they say "VeCOAX DIN has 170 milliseconds only of delay, so it is the perfect solution for any LIVE Application where no latency is wanted". 170 ms is definitely not "no latency". Also, the cost is quite high.

Edit: I just got an answer from their live chat that the latency on the VeCOAX Pro1 is "200 ms including the TV buffering". Too high for us, unfortunately.

it looks like in every situation you are getting a hdmi to sdi - sdi to hdmi converters ... get 2 and test your coax ... a hidden cost is the labor of replacing the cabling ... maybe you don't have to "pay" someone because you do it yourself but all time is worth money and if you can use the existing cabling then +1. its likely at distances of 150 ft you will be fine.

your "matrix" can be a sdi router, which from personal experience works nicely for your needs unless your trying to switch a show, if your just routing feeds its your best bet, otherwise you need a switcher which depending on how many sources you want to send out you maybe able to do with just switcher aux's and da's but i'd suggest you always use a router it just gives you best flexibility

personally i think it is best to keep all things standard its easier to trouble shoot ... various hdmi splitters can get very picky ... make it all sdi distribute and da turn back to hdmi done.

also in each situation you have a "live stream" is this a blackmagic product or otherwise read the forums to determine what blackmagic devices may be best ... personally we use teradek cube for streaming its all in one box and you just feed it a sdi signal well worth the simple setup imo.

Yeah, I think I'll just get the HDMI<>SDI converters and test it out.

I found more markings on the coax cable -- it's 5918A, which is:
"Type: RG6U CSA. Shield: 100% Aluminum foil, 95% Aluminum braid foam inlyethelene dielectric. Conductor: 18 Ga. Solid bare copper. Nominal O.D.: .270in."

That looks pretty close to Belden 1694A from the specs, aside from the sweep test rating. I think we'll be okay using the existing cable. Hopefully I'll have a chance to try it this week.

The live stream is done on a desktop PC using Flash Media Live Encoder. It's just one click of the button after the computer is started, so the operation is very simple.

For an application like this I would definetly conisder an encoder modulator, it will greatly simplify routing and distribution to move to RF. Then you would have each signal available on any display with a simple QAM tuner or STB. Otherwise you could move to a fiber approach. You could use CWDM transmitters for each SDI signal and multiplex them with a CWDM passive. You could then fire the whole multiplexed signal through a PLC fiber coupler and get 16 outputs that you could run to 16 optical receivers to convert back to SDI. One company that works with these types of compound systems is Thor Broadcast. thorbroadcast.com