Spectra8 (with expansion bracket) frame rate question

[skow]

I have an iTuner Spectra8 card with the expansion bracket providing a total of 8 BNC connections. Currently there are no cameras hooked up to any of the inputs and I am just testing things out. I am using ZoneMinder v1.22.2 and have all eight monitors configured, but the ones on the expansion card are disabled and set to a 'None' function. The frame rates on the cameras attached to the card itself in this configuration report 40fps when viewing them(Table 1). All cameras are configured the same (RGB24, 320x240, no max frame rate). When I enable any of the expansion card ports the frame rate on the pair drops to 5fps each (Table 2). I would expect the frame rate to drop to half, or slightly less than, the original frame rate, but switching between the channels of the chip seems to have a far greater impact on frame rate. Does anyone have any ideas on how to regain some of the lost frame rate?

Table 1:
Camera1 Record /dev/video0 (0) 40fps
Camera2 None /dev/video0 (1) 0fps
Camera3 Record /dev/video1 (0) 40fps
Camera4 None /dev/video1 (1) 0fps
etc...

Table 2:
Camera1 Record /dev/video0 (0) 5fps
Camera2 Record /dev/video0 (1) 5fps
Camera3 Record /dev/video1 (0) 40fps
Camera4 None /dev/video1 (1) 0fps
etc...

[jameswilson]

this pops up a lot so if you have a search you should find plenty on the subject. basically you can't as the frames are lost during the resync process, in theory genlocking the cams would stop this, but unless you have the cabling and top end cameras you wint be able to. If you have ac cams and can linelock them this might help but I have never tested my theory!