ZoneMinder Forums

I have a LMLBT4 and I am using it with Zoneminder 1.19. It is a 30fps board. When I am using 1 camera the zoneminder only captures at 25 fps, when using 2 cameras it captures at 5fps and with 3 cameras at 3.4fps. As far as I know it should capture at 10fps with 3 cameras.
I searched the forums for any hint but didnt find any.
I am capturing at 352x288.

Any help?

Thanks in advance,

Joel Moraes

Each chip (BT8xx) can usualy run at 30 fps NTSC and 25 FPS PAL on a single port. When you start switching ports to use more than one camera (BT8xx and other chips can only use one input at a time so in effect the inputs are scanned to use more than one camera) the transistors take time to switch so you lose time there then the newly switched camera has to sync and you lose time there as well.
I hope this helps.
Cheers,
Cordel

I find the same issue but in Windows the 'Diginet' software that comes with the KMC4400r it indeed gets 7 fps from four inputs to one bt chip.

How is it that windoze can do better frame rate than linux?? I thought some of the reduction is from the frame analysis that ZM does and Diginet does not.

I called Sonny at Security Guys (.biz) and they said they were not aware that the 4400r worked in linux so could not comment.

There are serious switching issues with the 4400 card tho ... either version, with the BNC's or the one with the pigtails on the VGA looking connectors. Either one, if I use all 16 inputs, there seems to be some sort of moire effect - each image seems to 'breathe' brightness; dimming and brightening in no particular logical order. Using two cards for 8 cams each solves the problem and improves the framerate to 5fps.

I do know that windows manages to get slightly higher fps than linux, and can only assume this is because of the driver to 2 use.
AFAIK the bttv driver is not optimised for multiplexing into a single chip and is mainly for consumer tv type use, ie holding a single input for a considerable period.

Its not a zm issue and i know one lad (lee i think) that says its down to bottlenecks etc. I have plenty of raw machine power and have never seen more then 3 fps per input on a single chip when using all 4.

Maybe a few of us could investigate why it works for some (well lee lol) and not others. ANd if we could find a card that did this and sis it well etc

Short answer... If you spend enough in hardware to get the most fps out of a split card, you can buy a faster card.

I did more testing because I was trying to get the best performance out of 32 camera systems. The driver only supports 16 chips, so you have to split. My result is that after about 24 cameras, you can not view a full montage easily, and the system is heavily loaded. So I never split more than twice unless it is a low cost build.