ZoneMinder Forums

This is from a single event, when you click to view "stills".

This happens in many places. If I click on a camera's "zone", I get the proper zone field, but the image is from another camera. If I click on 4 camera view, all 4 can show one view, then again can work as expected. If I click on a live view for one camera, it will cycle randomly through all of them, but sometimes remain on the proper camera.

It doesn't always happen, so it isn't a configuration issue. It is random, as is the interval at which the images change.

In the middle right image, you can see how the view changes. Almost like an old CRT TV getting signal from an over the air antenna.

I'm running on a 1.80GHz Celeron, my frame rate is limited to 2fps. What could be causing this?

You might need to provide some more info :-

What cameras are you using (make/model)?

How are they connected (IP Cameras on network or wireless, USB Cameras, 4-port analogue capture card, other ... ?)

I've seen minor confusions like this when trying to force a Hauppauge WinTV PCI to use both of its inputs ... it sort of worked, but then ended up with the same picture shown on both monitors when "provoked" too much, so I stopped trying that, it seemed to be some kind of timing issue ...

Not sure about camera models, but they are connected via BNC connectors to a BT878 card.
System is a 1.8GHz Celeron with 2GB of ram, on an INTEL D865GLC, and the load does go up to 1, often past that, so I'm thinking of getting something beefier. But figured limiting FPS to 2 would keep me within system resources.

Your card number is probably wrong. At this link is a good list of card numbers and if you can locate yours - http://www.tldp.org/HOWTO/html_single/BTTV/. Where this value is set is distribution specific but try searching for the location of bttv.conf as a suggestion. Also if you have more then 1 camera running on 1 chip then you'll need to set "catures per frame in options to a value of 2.

From lspci: So on the FAQ, under "Cards by Number", is the "rev 11" from lspci relevant to "card=n" in the list? I suppose should take the card out see what it is. The eBay auction listed it as Bt878a. Why do you think that number is wrong?

Not sure how many chips the card has but it has 4 BNC inputs, and I'm using all of them.

fafaforza wrote:Not sure about camera models, but they are connected via BNC connectors to a BT878 card.

That's the sort of card (analogue capture) I was talking about :-

"03:03.0 Multimedia video controller: Brooktree Corporation Bt848 Video Capture (rev 12)" supported by the bttv module, as you will have noticed.

On mine, there are 4 capture inputs (composite, s-video, tuner, not-used?) and a multiplexer that routes one of the physical inputs to the single capture chip. There is some kind of timing problem when trying to convince ZM to switch from composite to s-video, capturing from both in turn, that causes the pictures to get mixed up between the inputs, as you are seeing.

I don't have a resolution, sadly!

fafaforza wrote:is the "rev 11" from lspci relevant to "card=n" in the list?

"11" is the hardware revision of the chip (Brooktree capture chip, there's only one on the board) -- you need to know what the model of the card is, from the box/documentation/PCB silk screening ... Linux (well, bttv driver) tries to guess what your hardware is, and may not get it right. If it's got no idea: Assume "Generic". Giving a hint as to the model enables the driver to stop guessing and KNOW

This is what "your card number is wrong" means, not the BT878(a) bit, and that may fix your problem. Or not. Best to give bttv the best chance though!

Also note:

Setting Frames Per Second to 2 is not what you need to do, it's not about reducing load, it's about timing.

You need to look for "Captures PER Frame" and set it to 2 (at least), otherwise it really doesn't work. There needs to be a sort of cooling off period after swapping the multiplexer inputs between your 4 cameras.

If you try and capture every frame, you will get a horrid out of sync mess as it flips from camera to camera too quickly.

With captures per frame at 1, which is fine for a single camera, it will literally switch inputs, grab a frame, and move on, and that doesn't work well. With it set at 2, it will switch, capture one to throw away, and then capture one to use.