New wireless system advice
Hello from Berlin,
I've been building large-format interactive video installations using Isadora for some years now. The system I've been working with pulls 4 live video inputs, and outputs to 3 or more projectors. Everything is hard-wired. The live feed inputs come from 1080p IR security cameras wired with SDI cables (BNC connectors) via Blackmagic Decklink Duo 2 hardware. Projectors connect via fiber-optic HDMI. It's been a good system, at one museum it ran rock solid for 15 months straight spanning 2019-20.
My problem is the cables. They are too heavy and too bulky for travelling to rig shows, and a pain in the XXX to tuck away into the ceiling or wherever, so that they aren't a distraction to the installation. I'm looking for advice on my best options for wireless solutions for both my camera inputs, and my projector outputs.
Goal 1: Bring in 4 (or more) IR, 1080p (or 4K), live security camera feeds. I can't have the latency I've seen plague so many wireless systems. I also don't want to pay for a cloud subscription for the security cameras.
Goal 2 (tougher): Output wirelessly to 3 or more projectors at 1080p from a single computer.
Thanks in advance for any/all advice
well, 100-400 ms latency from the Rhombus camera's maybe ultra low for security, for your line of work it is way too much I think. I would forget wireless solutions for the beamers. It takes a lot of bandwidth with stacked wireless protocols to do it good but if you have 3 wireless links at the same time you would need a lot more bandwidth then currently available in wifi. In my line of work I use fiber or SDI to do so. One other problem if you go wireless, only the most expensive systems can give you a fixed latency, once you have some inference, systems will switch to a longer latency. This would be a disaster if you would stitch for example beamer images. For camera's you could maybe give it a go, but it all depends on what kind of resolution you like to work. Don't believe all the great user stories of wireless brands, it only works in a "perfect" situation with no other wifi signals and using one stream. Black Magic Design got a line of cheap converter boxes to go from HDMI to SDI or fiber and back.
Black Magic Design got a line of cheap converter boxes to go from HDMI to SDI or fiber and back.
I second the advice to convert the signal. Send signal over fiber, SDI, or ethernet and have boxes on either side. (I really don't recommend fiber for traveling to rig shows; it's expensive and fragile.)
Maximortal last edited by
I've reached 60ms of latency using an ValueHD PTZ camera connected through SDI-HDMI converter to a monitor. Usually projectors introduce a bit more latency. Using a wireless NDI setup you can reach about 200ms but with some drops or freeze. wireless is not a good option for now.
I do have experience with teradek bolt wireless systems. I used up to two of them in parallel several times, in a big stage show in an Industrial environment with up to 1200 visitors and distances (free air) of round about 30m. It was used for live camera feeeds which was shown in parrallel on the same stage as the actor was filmed on. Once they have a stable connection (first connect is tricky sometimes), they where pretty reliable, even with quick movements of the actors on stage (It was an streetart and artistic show with artists on bikes and skate boards etc.).
The latency is amazingly low at round about 10ms which could even be partly coming from other devices in the chain. My experience in general shows, that most converters and digital devices adding round about 10 - 25ms to the chain. Some monitors do more, espacialy if they are "smart" and do a lot of picture optimisation. Professional Projectors are usualy pretty quick. But some of them have different latencies, if they have certain options activated, like warping e.g. Sometimes they do have an option which is meant to lower the latency.
I don't know how many wireless signal lines are possible in parallel with the teradek and it probably depends on several factors, like wifi and other wireless systems around and the room it is used in, etc.
The other thing is, they are very expensive! One option could maybe be, to use only two of the 4k systems and split the signal into four. Which would add extra devices anyway but would get rid of the long distance cables.
Depending on the actual physical setup and the distances between endpoints ther might be one other wired option. You could use open industrial fiberlines (SC, LC, ST, etc. connectors) and combine them with sdi to fiber converters. There are fiber cables which combine several fiber lines in one multicore cable while keepin a very low diameter. This way you could work with two (or even one, depending on setup) thin long distance cables only and split them opticaly near the projectors/cameras. These are used often by event tech rental companies and my experience is, them beeing more reliable then people tend to say. Only issue most times are the end caps, which can be cleaned or exchanged.
mark_m last edited by
I would echo @DillTheKraut's experience of the Teradeck Bolts: their latency - or lack of - is great, but they are expensive to buy or rent.
I own a couple of pairs of the VAXIS ATOM 500 SDI which has 70 - 120ms latency. I use them for a variety of purposes, mostly for 'roaming' cameras when filming / livestreaming events. The latency is OK, not perfect, but you have to be watching very closely to notice it when watching a live switched show. I recently used a TX/RX pair on a projector in a theatre where rigging the projector was easy but running the cabling was stupidly difficult, and it worked very, very well.
There's a review here which echoes my experience
The Holyland Mars is a similar bit of kit.
The best thing about both of these is that they're very inexpensive for what they are.
Mark (t'other one)