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Low latency IP Cameras(less than 200ms)

Posted on 2011-02-15
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Last Modified: 2012-05-11
Were going to mount cameras on a moving vehicle connected through a fibre to a control room. The cameras mounted on the vehilce will serve as the operators eyes, and need to deliver video with very low latency. I see that many producers of IP cameras state "low latency" as one of their criterias, but the delay is not mentioned in the datasheets, and the producers haven't done any tests.

So I'm hoping someone here can guide me in the right direction. We're thinking H264 or MJPEG, communication through a RJ-45 plug and Cat cable connected to a fibre MUX.

We will choose a software package that promises low latency, but right now cameras are most important.

Any suggestions?
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Question by:nebb-tgr
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8 Comments
 
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Expert Comment

by:aleghart
ID: 34902254
Why deal with shifting latency numbers and network issues?  Use a live feed, then split it two ways for (1) live monitoring  & (2) recording/distribution.

Give these folks a call and see if latency over your run length is significant.

http://www.versitron.com/fiber_video_digital.html
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by:aleghart
ID: 34902295
Sorry, I missed this: Stacking compression/decompression on top of the network latency...is this low-speed maneuvering (low accuracy)?   I still think that analog cameras will have less setup and troubleshooting issues.  You can also get them smaller and bulletproof, with a quick&cheap swap out if there's a problem.  IP cameras can get expensive.
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by:nebb-tgr
ID: 34904673
Everyone keeps saying that analog cameras are the best for this kind of setup, and we are thinking of a solution for it.

Analog cameras connected to fibre MUX with X video inputs
Fibre DeMUX is connected to Y-splitter.
One part of the feed is input to the TV/monitors
The other part is input to a digital recording system

Is this what you had in mind?


The thing is: We can factor out network latency. Because that latency will be present in both solutions. The core of the problem is the latency from picture taken to the signal reaches the first ethernet-cable.

The video signal has to be transferred over fiber either way you do it.
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Expert Comment

by:aleghart
ID: 34906291
Yes, I was imagining users with controls at the end of the fiber, with encoding/recording happening for documentation and non-real-time remote observation.

The "drivers" are using live video for visual reference, not the encoded video.  Although, encoding at that point can be more predictable because you can have rack-minted equipment doing the grunt work instead of tiny chip on the moving vehicle.  For replicating results, every camera swap out (analog) would not be introducing variables.
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Author Comment

by:nebb-tgr
ID: 34906339
What kind of cables would you use in this situation?

Analog cameras with HD resolution, what kind of output do they use? I'm guessing Composite video will not give enough quality, so you would have to use component?

I'm asking because we also need to find a suitable fibre MUX that is compatible with this solution. Like you, I'm sure everything in the operator environment is pretty easy. The problem is fitting things on the vehicle. Components need to be small, have as few pins and connectors as possible, have good quality etc. This issue is further stressed by the fact that this is a underwater vehicle, so the electronic containers price is very much dependant on the size..

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aleghart earned 500 total points
ID: 34906738
For high definition work, you would be looking at digital cameras with on-board processing.  I don't know of any single-camera HD analog units.  NTSC/PAL can run analog over closed circuit.  HD is digital.

I've seen multi-HD cameras with fast on-board processors.  They can feed multiple streams simultanously, and allow digital zoom in a monitor feed while still recording the full frame without interruption.  Latency numbers, I can't find.  You'd have to call the mfr _and_ do your own tests.

Here is a multi-cam setup, (4x)1600x1200 in an IP66 dome.  For underwater, you'd probably want an IP68 rating from the OEM.

Each cam covers 45-degrees, so you get 180 field of view.  The spec sheet lists 6400x1200@5.5fps, with bandwidth up to 10Mbps.  Higher frame rates mean lower resolution.  But, it would make for a nice dashboard.
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by:nebb-tgr
ID: 34907389
A possible setup would be:
HD camera with composite output
Fibre mux with composite input
Fibre mux with composite output
Y-splitter, one part for viewing, the other for recording and storage.

Would we experience any latency apart from the network latency?

How would this solution work as opposed to digital cameras with built-in H264 encoders? I'm thinking mostly about latency, but other factors as well.

Our current problem is that we have heard that encoding video to H264 or similar would create too much latency. So how can we get the latency down to almost ideal real-time with HD quality?
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Author Closing Comment

by:nebb-tgr
ID: 35126631
Didn't choose any of the cameras he suggested, but some of his points were very useful.

We will analog cameras and high-speed encoders or fibre MUX in order to get the video through to top-side.
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