OmniVision 7648

Unless you are using some form of strange frame grabber, WHY slow it down?

These devices are normally used in continuous o/p of video. This helps the auto-correction hardware work over several frames of data, which it cannot do by running slow or only for a few frames.

What sort of problem and where are you seeing the problem..

I have worked with some Omnivision devices and normally when I see people having problems with these devices it is normally because they do not understand the way video works.

-- Paul Carpenter | snipped-for-privacy@pcserviceselectronics.co.uk PC Services GNU H8 & mailing list info For those web sites you hate

Hi Paul,

Thanks for your reply .Now let me explain you the problem.

I am making a driver for OmniVision 7648 so i want my driver should suport all the different type of frame rates which are supported by h/w. Camera captures data and gives to a Video Input Block(VIB) of an ARM based SOC which in turn display the data on Overlay window.

QVGA works fine on every frame rate.But VGA when we lowered the frame rate below 10 is gives huge GREEN linings on the displayed frame.

I have checked that the probelm is not in overlay settings coz if I capture the video in file and play it on PC it shows same green linings.

Also VIB setting are fine because they worked on other frame rates.

For lowering the farme rate I just changed the CLOCKPRESCALAR register of Omnivision 7648.

Thanks for your help.Can you suggest OmniVision settings?

Which is basically TWO frame rates for that type of device VGA and QVGA/CIF.

If below 10 you mean frame rate drops to 10Hz (10 frames per second) then I am not surprised personally. I do not see why you need to go that low a frame rate. If you don't need to go that low then don't allow the software to do it.

So you are still lighting the object the same you have same exposure and other settings, so may well be blooming or other aspects of the camera, colour correction and/or decode circuitry is being overloaded internally.

CLOCKPRESCALARS are for allowing different master clock frequency inputs to make the internal clock of the camera the same rate, You are no doubt using the same master clock frequency.

I think you are trying to do something the device was not designed to do.

You don't change frame rates (on the same master clock input) without changing other settings or external factors change like lighting.