What causes saw tooth pattern on histogram?
 

I am finally making some progress! Do I know how or why--NO :question:. VD just seems to like me today.

I was able to look at the histogram for the video fed to my VC500. It was an odd pattern because all across the top edge there was a saw tooth pattern where the level rose then dropped to a baseline level at equally spaced intervals. I put my HVR-2250 card back in and it does not show a saw tooth pattern. But, as I was stepping through the Capturing with Virtualdub Guide, the saw tooth did appear when I changed the frame size in Set Custom Format from 352x288 to 720x480. Why?

The biggest, positive surprise today is that VD is allowing me to show the preview video, histogram, and levels at the same time with the HVR-2250 card :yahoo1:. This did not work yesterday during my day long marathon trying to get a capture device and VD to work together.

BTW, thanks for the capture guide. It's great!

Steve

Sawtooth? Were you seeing some sort of drop-field deinterlace? :question:

I took pictures of the histogram while using the HVR-2250 and VC500 capture cards.

- File "FS-HD-2000U with HVR2250 no saw tooth 352x288 (2).JPG" shows the histogram for the HVR-2250 card with a 352x288 format. No saw tooth.

- File "FS-HD-2000U with HVR2250 saw tooth 720x480.JPG" shows the histogram for the HVR-2250 card with format changed to 720x480. Saw tooth pattern.

- File "FS-HD-2000U with vc500 saw tooth 720x480 (2).JPG" shows the histogram for the VC500 card with 720x480 format. Saw tooth pattern. This card did not allow any other formats.

Any thoughts about saw tooth pattern?

Thanks,
Steve

Did you ever find out what this was?

I've seen this with the VC500 as well, it seemed to be something to do with contrast setting. It would appear and disappear depending on what the contrast was set to. Maybe it is a result of some values being squeezed or stretched?

The sawtooth pattern changes based on the capture card and the proc amp settings. I wondered about it at first. Now, I just ignore it.