ZoneMinder Forums

Hello,

my current setup holds two cameras on one generic 1 chip 4 port bt848 card. It seemed to work like a charm, but during the last weeks I came across several problems.

If I activate more than one input at the same time the picture seems to get worse - could this be an interlacing issue because of the dropped framerate I get with more inputs on one chip?

The main cam seems to have problems to adjust to the lightning for some unkown reason and therefore the picture sometimes gets periodically lighter or darker. As long as I have just one cam on modect everything works fine but as soon as I activate the second one I get much more false alarms than before. Could this also be a result of the dropped framerate? My guess is that the lower framerate results in a greater difference between single images.

Right now I am considering to buy two additionional cards of the same kind (aiming at three cams) but I wanted to ask if there is a good chance that this could really solve my problems.

Have you edited the options file in modprob.d folder and added "options bttv card=77 " ??
Check your dmesg log and see if the OS sees the card and has set using driver 0 or 77 or another driver. javascript:emoticon(':D')

thanks for your advice.

yes, I've set "options bttv card=77 " - this was neccessary to get the card working and to be able to see anything on the screen.

I have played with a few 4 ch cards with 1 chip.
they will run at 5 or 10 fps with 1 cam as soon as you hook more than 1 the frame rate drops to below 2 fps. Pretty much all 878 chips will be blurred or interlaced at any res larger than 320x240 .

Also Most important with the single chip cards is that ALL the camera settings MUST be the same. 1 chip can only run 1 setting for each parameter. Except the camera source of coarse.
I have ran 3 of these cards 1 cam on each for 5 bucks each it was cheap.
You have to add ,77 for each card you add.

That's a common problem with sharing ports on a capture single chip. You'll get a frame rate drop as there is a delay slight delay when the capture card hardware changes channels. You'll also get an interlaced-looking picture off and on because that first image the card spits out right after a channel change isn't ready. If you lower the resolution to 320x240, the picture won't look bad anymore but sometimes it will jump up and down.

You can chose to live with the drop in picture quality or you can set ZM_CAPTURES_PER_FRAME in the ZM option's config tab to 2. This will fix the picture quality problems but will drop the frame rate even lower.

The lighter and darker problem sounds like the side effects of a lower frame rate. When viewing at a lower frame rate, lighting changes will seem more drastic.

The harder you work the chip (switching) the hotter it gets. I am betting you do not have a heat sink on it...