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Camera is bright but dim viewed in ZM

Posted: Fri Oct 13, 2017 6:57 pm
by BobLaske
I have a color camera installed outside which is always nice and bright but when viewing the same camera connected to a grandstream gsx3504 and viewing it through ZM, the image is very dark.

Again, searching for days so thought I would ask here.

Re: Camera is bright but dim viewed in ZM

Posted: Sat Oct 14, 2017 7:44 pm
by mikb
More info needed: What model camera, and what kind of camera (analog? IP? Other?) and how is it connected to your PC (USB, wired network, wireless network, analog capture card)?

Re: Camera is bright but dim viewed in ZM

Posted: Sun Oct 15, 2017 12:04 am
by BobLaske
Sorry, I thought the fact that I mentioned the grandstream might give that info.
The grandstream is an IP encoder. I'm not sure what the camera is, something that came with a ZModo package deal which I upgraded from cmos to ccd.
Yes, analog, video only, connected to one of the gsx3504 video inputs.

I have a splitter on the video output of the camera, one to the grandstream and the other to a video monitor. The image is bright on the video monitor but when viewed using zm, it is very dim. I'm guessing the problem is the grandstream.

Re: Camera is bright but dim viewed in ZM

Posted: Sun Oct 15, 2017 7:32 pm
by mikb
Okay, so you are splitting an analogue baseband video signal (1V p-p composite?) into two inputs.

Are you using a proper splitter that matches the impedance (with an inevitable loss of signal level), just wiring them together in parallel, or using an amplifier to maintain the signal?

Is it possible that the video monitor is compensating for your mismatched video signal, with an automatic gain control, and the grandstream IP encoder is delivering a picture exactly as bad as it really is :)

What happens if you just connect the camera to the grandstream, no monitor, no splitters?

Re: Camera is bright but dim viewed in ZM

Posted: Mon Nov 20, 2017 3:20 pm
by BobLaske
Hi, thanks for the reply. Sorry for the long delay, I don't seem to be receiving the notifications.

That was a good call so I tested that. There is an RCA splitter from from the camera output which goes into the grandstream then to a small LCD screen which I use for troubleshooting. I took that out and connected the camera directly but it's the same.

I changed the input on the grandstream to another one and it's the same. It's something to do with the camera when connected to that port. A different camera shows up nice and clear on that problem port.

No idea but I'll keep testing since it must be something to do with that particular camera and the grandstream.

Re: Camera is bright but dim viewed in ZM

Posted: Mon Nov 20, 2017 6:28 pm
by mikb
Good test, shame it didn't show more positive results!

It still could be a problem with termination, inside the equipment, -- I recall (years ago) a problem like this connecting the output of a "Telebox" (analogue UHF TV tuner in a separate box, basically a TV set without a screen or speaker!) to an Apple-branded monochrome monitor sat on an Apple II+ computer.

I had a three way switch, between 40-column text, 80-column card, and "TV" mode :) -- and the TV mode was really dim.

It ended up needed ADDING a 50 or 75 ohm "terminating resistor" at the switching point, for the telebox, before the picture came up to an acceptable brightness. Never quite worked out why it didn't "just work".

If there are options (dip switches, links, software?) for enabling and disabling termination on the camera OR the input of the Grandstream, check them. Otherwise is might mean a little playing with hardware.

Re: Camera is bright but dim viewed in ZM

Posted: Mon Nov 20, 2017 6:42 pm
by BobLaske
Right, that's interesting and I've seen that sort of thing too.

All I can think of is that for some reason, this camera is experiencing a weak video output. I connected it to another port and it did the same. I connected another camera to the same port that this dim camera is on and it was fine, nice and bright.
The dim camera outputs just fine when connected to a tiny 4" LCD screen I use for testing but maybe that's the key. Maybe that little LCD simply doesn't need much signal so the weak video from the camera is not affecting it. Perhaps the grandstream is expecting a bit of a stronger signal.

I'll try yet another test in the near future, putting a stronger video signal at the end of the same wire to see what happens.