Video relay / MD cam distribtuion

[timsabre]

I've tried both and the £30 ones from Amazon seem to function just as well as the expensive blackmagic ones.

[TomHoward]

Looking at it, SDI or HD-SDI and coax seems to be the way to go.

Think we will look at distributing in SDI, pull new coax in, get some SDI splitter and SDI-HDMI for the displays (as every display has HDMI by now), and either an SDI or HD-SDI camera to replace composite.

 

Two things-

 

Is RG59 good enough for HD-SDI over distances like 50-100m or should we look at better coax?

 

With regards to splitting SDI, how bad are passive SDI splitters at a local level (say for two screens within a band pit), or should ideally it all be actively split at a central point?

 

Thanks in advance

 

Is there a general good supplier for these bits and pieces (CPC, or a security supplier etc) or is it mostly ebay/amazon for the cheap stuff?

 

I think I'll get some composite - HD-SDI convertors and HD-SDI - HDMI and just see how that latency compares with our composite setup. I guess there'll be latency at the camera with the conversion but that may be recovered at the monitor using the digital inputs.

[Dave m]

I have split HD-SDI locally to feed two HD-SDI monitors and it's ok.

 

I have used a (black magic I think) composite to HD-SDI converter and the delay was massive.

HD-SDI to HDMI is near instant.

 

I would avoid any analogue to digital or VV process - stick with either digital or analogue but not a hybrid.

[Tim gregory]

I have split HD-SDI locally to feed two HD-SDI monitors and it's ok.

 

I have used a (black magic I think) composite to HD-SDI converter and the delay was massive.

HD-SDI to HDMI is near instant.

 

I would avoid any analogue to digital or VV process - stick with either digital or analogue but not a hybrid.

 

In my experience BMD Composite / component to SDI converters only add lines of delay. If your getting masive delay then its probably because you have the converter doing scaling as well.

 

Tim

[sleepytom]

I would recommend the http://www.oupree.com/Professinal-3G-HD-SD-SDI-to-HDMI-Converter.html - they are about £60 each and have a reclocked loop output which means you can chain clusters of monitors.

 

(buy online direct from china http://www.aliexpress.com/item/3G-HD-SD-SDI-to-HDMI-Converter-Box-Support-3G-HD-SD-SDI-Output-to-1080P/1918465369.html?spm=2114.01020208.3.2.CkVZuW&ws_ab_test=searchweb201556_3_79_78_77_80,searchweb201644_5,searchweb201560_1 )

 

Oupree are chinese but good quality, the SDI to HDMI pro converter is great and works on 5v so can be powered from the USB socket that you find on lots of modern screens.

 

Regarding cables then people talk a lot of rubbish about RG cable types, in reality the RG system simply tells you the external diameter of the cable, so really its not much use as a way of telling if a cable will be good or not. I would recommend HDSDI coax from VDCtrading or Direct Cable Systems or Beldan. choose a cable which is designed for HDSDI (cost will be at least £1/meter for decent cable - the 30p/meter satellite coax isn't any good for HDSDI!) Take care when terminating it and make sure that the pins are correctly crimped on! http://www.directcablesystems.com/ www.vdctrading.com or bryant-unlimited.co.uk are all decent suppliers.

 

 

Cameras wise there are loads of HDCCTV cameras which are affordable and provide a decent quality.

[TomHoward]

Can anyone recommend some SDI splitters / distribution amps? We could do with a couple of 6-8 way ones as part of this system - or a switcher with enough ins & outs to do the lot, but it may be simpler with splitters as not always the same lines would be the camera incoming anyway as the MD can move around depending on band location.

 

I had a look at Oupree but I can't see them make one?

The blackmagic ones aren't that expensive though - seems to be about £150 for a 1x8 - there are 1x4s on eBay for about £50 but I can't specifically tell if it's reclocked.

Does reclocking add and significant latency?

[Dave m]

Do you really need amps?

I would have thought that a radial system with a BNC patch would suffice. If you wanted to go upmarket then you could have a musa patch

[TomHoward]

the locations don't work for the show ready split well - we've got about 6 TVs across foyer, onstage and rooms backstage - the MD camera actually could be as there's only a local mon and then out to 1/2 in the house - but for one of the lines (and the the cable runs as well) it'd be easier to feed all from one location

[david.elsbury]

The BM ones are fine, if a little prone to overheating? Or at least getting super hot. We also have some extron 1:4's at work.

[sleepytom]

reclocking adds less than 1 line of latency, it's imperceivable without specialist measurement equipment.

 

I would avoid Blackmagic DAs if possible as they will not pass 3G SDI level A. Until they sort this out I cannot honestly recommend any of their infrastructure products.

 

 

 

[TomHoward]

3G SDI we need for 1080p? Which I guess it what we'd be running at ideally rather than 1080i?

Funny the Blackmagic boxes seem to claim they do - this is just dodgy advertising then? Is there anyone you'd use instead?

 

Ah I think I've worked it out - CCTV cameras would generally be 25fps and 3G is needed for 50/60fps.

I guess this means the BM ones would be rubbish for future use, but would work for our cameras at the moment?

I appreciate that's not a particularly long term attitude, but if the cabling we pull is 3G capable, the lost cost of the BM boxes might be worth a punt? I can't see anything else 1:8 in that price range - other than chinese stuff where it isn't really clear if they're re-clocking or what - if they are powered is it generally safe to assume so?

[TomHoward]

Just to add some final info to this - we got cameras, HDMI-SDI for laptop input, SDI-HDMI for all the outputs, and 4-way 3G SDI splitters all off Aliexpress.

All convertors were in the style of the Amazon ones (but there are two types - one is slightly smaller than the other, and although rated 5-12V only works with 12V, so won't run off the USB on the TVs) and rather than using 8-way amps, we send 4 ways and then split a second time at some of the remote locations - because for things like band pit we're looking at a lot in a similar location anyway.

 

Tried with the existing coax in the walls and it works okay - going to pull more coax lines to supplement more locations as currently we run over cat5.

[TomHoward]

I have three quick questions, just in case anyone is still reading this waffle.

I'm looking at the remote connector plates and a patchbay to pull them all together..

 

As a general rule, do I want to use the grounded or isolated BNC connectors? The grounds all seem to be common on the spitters, but at the remote plates, should they be isolated from plate and each other, and and the patchbay all grounded or floating?

 

There's no issue with the solder connectors is there? I don't need to go to the effort of crimped connectors do I?

 

In practice, are the D-mount BNCs usable with normal connectors rather than the 'rear twist' or are they to deep to get the connectors out?

D-mount would be safer from damage on the remote plates but I'd use the proud ones if they're difficult

[david.elsbury]

I'd suggest isolated bnc's as you don't want to introduce ground loops by tying to mains earth. Shouldn't hurt anything anyway by using them.

 

I think crimp is preferred as it maintains impedance better, solder can be a bit unpredictable and the bandwidth of 3G-SDI is much higher than analog composite video.

 

No idea on question 3 sorry :-)

[TomHoward]

Are crimped and passthrough okay or are the cable crimped one-piece cable jacks preferred?

The patch bays are more common as passthrough, so crimping cable sockets may be easier.

 

Does anyone know about the crimp tools - the Neutrik tool is a fortune compared to generic ones - is it worth the extra money?