# Low-latency IP cameras



## Sparks & Light (May 17, 2019)

Have a situation where we want to set up an IP camera on the director in the pit and a display for singers backstage. I've tried security cameras but the ones I've looked at have a delay of at least 200-300 milliseconds, sometimes more depending on the codec settings.

I'd like to use a networked camera to avoid the hassle and expense of cabling. Are there any cameras out there that provide a more real-time feed?


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## ruinexplorer (May 17, 2019)

If you are on a tight budget and require very low latency, you are going to want to look at older analog cameras/display. You will be using composite signal over co-axial cables. 

If you are requiring a networked camera, you are going to get latency due to the processing of the signal. If you already have Cat-6 cables run and you can avoid network switches (i.e. dry lines or patch bay), then you might consider a HDBase-T system.


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## AlexDonkle (May 18, 2019)

With the technology today, I think you'll be better off with HDbaseT (over Cat6 STP) or SDI (over coax) rather than a true IP camera. Marshall POV cameras are pretty popular for this. The broadcast industry is in a slow process of switching over to IP at the moment, so you'll likely start seeing better small, low latency IP camera options in the next few years, but I haven't seen any good IP conductor camera options yet.

If you want to go the IP route though, I'd suggest taking a look at this, just to confirm your current camera is the issue, as IP video systems have several possible sources of latency: https://www.axis.com/files/whitepaper/wp_latency_live_netvid_63380_external_en_1504_lo.pdf


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## Jay Ashworth (May 19, 2019)

Everyone else is being polite. I'll be (in the immortal words of Tina Turner) .. rough.

No. There is no possible way you'll get conductor-level latency out of a IP camera. 300ms is *fantastic* for that, it can often get up close to a second. Even hardware MPEG encoding is slow by comparison to frame rates.

Analog all the way to an analog CRT is the only 100% reliable way to get microsecond latency.

*Most* SDI and *some* HDMI cameras can stay down around 1-2 frames, and *some* monitors can lock to that, or at worst, lose only another frame in conversion. But it's going to take some experimentation to get it right.


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## Scenemaster60 (May 20, 2019)

Again, depending on your budget, I've had good results using the Magenta Multiview technology for transmitting video over cat 5e cabling.
While this technology still works perfectly well, I think it is more or less sunsetting as a "go-to" for video transmission with the nearly universal adoption of HDBase-T for 4K video over cat 6 cable.

When purchased new, these units were quite expensive ($800-$1000), but you can often find transmitters and receivers on ebay for pennies on the dollar. From my look this morning, you could probably score a transmitter and receiver for well under $100.

The entry level units transmit and receive a VGA signal over up to 500' of cat 5e cable. Other than a video camera itself, you will also need a convertor to change either a 480i composite video or HDMI video to VGA. On the receiving end you just use a large computer monitor with a VGA input (and we all have some of those lying around...)

I used a Multiview 500A/S transmitter and Multiview 500A receiver in this capacity as a live monitor for the organ console at a large church in Minneapolis for about 3 years. I won't say there is no latency in it (I'm guessing it's less than 10ms) but the organist never complained that it was a problem when accompanying choirs and orchestras via the monitor.

Also, if you're using building data cabling, you'll obviously need access to the switch room so that you can remove both data runs from the switch and simply jumper them together. That's what I did at the church and it worked just fine.

Here's the brochure of the Magenta Multiview product line from a while back:


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## Sparks & Light (May 23, 2019)

Thank you all for the replies. I had hoped for something IP based, and I see that I'm out of luck. As @Scenemaster60 notes, I would have to have access to the wiring closet to repatch the cat5/cat6 to run HDBase-T.

I shall, as we so often do, figure something else out.


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## Sparks & Light (May 23, 2019)

Jay Ashworth said:


> Analog all the way to an analog CRT is the only 100% reliable way to get microsecond latency.



I know we're both just geeking out here at this point, but remember that with analog the display is, on the average, half a frame behind, because of the nature of the scan; we perceive the older part image due to a combination of persistence of the phosphor and persistence of vision until the electron beam again reaches it. So about 17 mS. 

A more interesting question is what is acceptable for the application. I would guess around 50 mS would be good enough.


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## Jay Ashworth (May 24, 2019)

Yeah; I quoted this recently (somewhere) as a minimum perception time of about 120ms; that was wrong -- it includes the *response* time. The actual minimum perception time is apparently around 17ms; half a frame.

It is, I think, theoretically possible to keep the chain delay around 3 frames, and I suspect that would work, it's just damned expensive. :-}

And of course, it depends on the material.

Bolero? Just fine. Bumblebee... yeah, no.


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## Ancient Engineer (May 29, 2019)

I use the Marshall cameras here over HD-SDI with excellent results. About a frame or less of latency from camera to destination.

Your mileage may vary...


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## MNicolai (May 29, 2019)

I tend to like the Marshall's as well via HD-SDI. With the interchangeable lenses you can get a lens that matches the view you need for your stage.

Key thing to remember is that with projectors and cameras, you almost always want to be on the wide end of the lens. Just because you can 30x zoom doesn't mean you should -- you're throwing away 40-80% of your brightness by zooming all the way in. Get the right lens for the view your need.


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## BenJ_dp (Jul 30, 2020)

I'm a bit late to the party. I don't know if anyone thought of using some FPV (First Person View) used with drones? Most are analog to keep the latency very low (below 30ms). You can see some screens here. There's also DJI that released its DJI FPV which is low latency but digital. I'm not sure of the quality of the video/lenses (the DJI one should be quite good, the analog ones not that much).


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## MR_AV (Oct 22, 2020)

I found this camera and we are using it on an upcoming conductor system project together with IP-NINJAR from IDK (see my post in another thread). The expected latency from camera to display is below one frame.


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## Jay Ashworth (Oct 22, 2020)

Well, you're almost always going to lose one frame per interface anyway, unless everything is genlocked, but it'd be interesting to know more about those Ninja boxes...


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## jtweigandt (Oct 22, 2020)

I have used an ultra cheap mini sized analog “spy” camera for this for years. Less than 20 bucks.. Picture is clear as a bell.. adjusts to ambient light extremely well. Goes to an RF modulator to convert the raw signal to Tv Channel 3.. coax to a splitter and out to 2 old donated TV sets. I have 3 or 4 more old analog TV’s in storage for when the others go to their celestial discharge.

ours looks something like this... this one is a bit more and higher res.. but I’m sure if you shop around you could find an old plain vanilla one https://www.ebay.com/itm/1080P-HD-H...4392a3dd64900bf23af9|ampid:PL_CLK|clp:2334524


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## Jay Ashworth (Oct 22, 2020)

jtweigandt said:


> I have used an ultra cheap mini sized analog “spy” camera for this for years. Less than 20 bucks.. Picture is clear as a bell.. adjusts to ambient light extremely well. Goes to an RF modulator to convert the raw signal to Tv Channel 3.. coax to a splitter and out to 2 old donated TV sets. I have 3 or 4 more old analog TV’s in storage for when the others go to their celestial discharge.



Well, yeah, but the largest monitor you can get that's a CRT (and hence subframe delay) is 36", and those weigh a quarter of a ton. NTSC into any LCD loses you at least a frame, and 33ms can be enough to cause a problem here...


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## jtweigandt (Oct 22, 2020)

Who says you want or need a large monitor. We’re using probably 14 inch diagonal portables. They sit on a single arm wall monitor tray and are about 8 feet off the deck One stage left, one stage right... A whole chorus of people see them and sing with them just dandy. Been doing this a long time.. probably put in the pit camera for the first time maybe 15 years ago. First hauled in my Sony monster first generation 8 mm camcorder, then later the little micro spy cam. KISS applies here. Think of the arc filled by the directors body from the perspective of an actor onstage.. I can block him out with my thumb, and (when I look at him) I have no problem taking direction. The monitor, even a 14 inch presents as big or bigger image of the director than you get onstage.


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## Jay Ashworth (Oct 22, 2020)

Opera singers, 55 feet from the front of the balcony, 20 feet in the air, that's who.


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## jtweigandt (Oct 22, 2020)

Jay Ashworth said:


> Opera singers, 55 feet from the front of the balcony, 20 feet in the air, that's who.


but the discussion here was for offstage singers. And my comments were how I have done this successfully for over a decade


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## MR_AV (Oct 23, 2020)

Jay Ashworth said:


> Well, you're almost always going to lose one frame per interface anyway, unless everything is genlocked, but it'd be interesting to know more about those Ninja boxes...


Here you will find some more information about the IP-NINJARs: http://idkav.com/ip-ninjar-video/. Attached you will see a photo of a small test setup: left display is the timecode source via HDMI loop out of IP-NINJAR transmitter. Top right display is the timecode source transmitted via TX + switch + RX. Middle top display is camera signal via HDMI loop out of TX, middle bottom is camera signal via TX + switch + RX. The camera caused approx 2.5 frames of latency as you can see, the transmission parts are by far below one frame.


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