Video Pulsing Problem

[Brian Maynard]

Hi,
I am still a rookie and searched for a similar problem, but didn't see anything so I thought that I would ask.


I videotaped an event last weekend with two Canon XH A1 cameras. I taped in 3 different locations. After capturing the video to my computer, the video from the first two locations looks fine, but the video shot in the last location has a slight "pulse" every 1/2 second or so where the brightness and color changes very slightly. I can see it on the Canvas and on the Waveform scope.

Any ideas what is causing it. It was taped in 1080i60 at 29.97. First I thought that the problem was caused because the sequence was set to anamorphic DV, but when I viewed it in HDV, it had the same problem. It is not real noticeable, but I noticed it. Is it a lighting issue?

Thanks in advance for any help.

Brian

[Jonathan Massey]

could be that you filmed in an interior and the light frequency was messing with the shot as the shutter settings were not in balance with the light source ( for example this is really noticeable when filming a computer screen).
I Always manage to avoid this problem, but perhaps a de flicker plugin can fix your image.

[Brian Maynard]

Hi Jonathan,
thank you for taking the time to help.

A "deflicker" plug-in? I have never heard of that, but it is a good suggestion and I will do a search and see what I can find.

Thank you.

Brian

[Robert Lane]

If you shot in any auto-exposure mode it could also have been the camera making constant white-balance and exposure changes, the pulsing might be minute shutter-speed changes made by the camera - at not too uncommon issue when in auto modes.

If you could up load a few seconds of the clip we could better identify the possible cause and solution.

[Brian Maynard]

Hi Robert.
Thank you for taking the time to help.

The video was shot in auto-exposure mode and I think that your analysis is correct.

Assuming that is the issue, can you suggest a fix?

I see that there is a "deflicker" filter in FCP. Would that help?

I also read a post that suggested that there is an After Effects filter that might help. Any detail on that would be appreciated.

I will get some of the footage up in a little bit also.

Brian

[Robert Lane]

If the problem is in fact auto-exposure "pumping" then a de-flicker filter won't help, de-flicker is actually used for a something unrelated to exposure so it wouldn't help anyway.

Unless you're in a constantly changing lighting situation that makes it impossible to track manually such as a fast-moving event (reality TV comes to mind) you should *always* be shooting in full-manual exposure. Any auto-exposure should be limited to iris (aperture) and white-balance only and shutter-speed should always remain fixed.

It would take an expensive session in a professional color-correction facility to manually correct these pumping issues frame-by-frame, so you may be stuck with the final result. Until I see a clip however I can't offer any method for masking the problem.

[Chad Dyle]

I just updated a post I started about this. Here is the link to a clip that I made of what is happening to me.

www.chaddyleproductions.com/video/sample.mov (Right click, "Save As")

[Mitchell Lewis]

What format is that MOV? Quicktime can't open it on my computer.

[Robert Lane]

Right, that clip is either corrupt or isn't in a supported format that any Mac-based player can handle. I haven't seen a clip from Brian's issue either.