View Full Version : Color displacement after capturing DV footage


Phil Gosselin
November 13th, 2008, 01:27 PM
Hi all,

First thing first, I am not the FC user that will edit what this post is about. I know my way around forums and he doesn't so that is why I am posting this question.

Pretty much since my collaborator switched to FC7 he started to have issues when capturing DV footage. His gear is 2 Z1 camera and 1 Sony HDV/DV tape deck.

DV footage looks fine in the viewfinder and on the monitor but once it is captured
(as you can see from the attached files), color is displaced and it almost seems like the picture is out of focus.

This happens pretty much with all DV shoot we've had for the last 6-7 months. Thing is when we shoot in HDV this effect never happened, same gear different results...

Any ideas as to what goes on in the capture step that makes it come out so?

Thanks

Phil

William Hohauser
November 13th, 2008, 11:18 PM
Where is the "color shift"? If you are referring to the intense reds, that can be expected. If you exported a still from the timeline instead of a screen grab from the FCP desktop, I think you would find the image to be sharp.

FCP and many other NLEs downgrade a DV file's image on the computer screen to reduce processor resources while playing back. If you played back thru firewire to the camera then to the monitor, the image should be sharp. Except if you are editing on a timeline with a different codec then the DV file. If you have a bright green line over the DV files in the timeline then the files needs to be rendered before it plays back clearly.

Bill Davis
November 14th, 2008, 02:54 AM
First I'll agree with William. Be sure you're judging the actual camera signal output not the proxy video generated for the FCP interface.

That said, looking at the picture of the singer, I'm leaning to thinking that the actual shot IS out of focus. The wide shot tells me that the redhead singer and the trumpeter are abut 8 or 9 feet apart. Given that it's stage lighting and there's a LOT of dark draping sucking up light, I'd expect your camera to be running with the iris pretty much wide open, and you'll have a really limited depth of field, even with a small chip. The fact that the background horn section players are reasonably clear makes me suspect that the camera focal length is falling somewhere BETWEEN the subjects.

But neither shot is really not very sharp anywhere, so I'd wonder if your camera has a back focus problem.

Are you saying that your shots are Tack sharp on a real monitor at the location? (NOT the LCD on the camera - which are notorious for falsly making soft focus shots look sharper than they really are!)

Probably be a good idea to go on line and print out a back focus chart and run the camera through basic focus tests.

My 2 cents anyway.

Aric Mannion
November 14th, 2008, 09:57 AM
That's what my HDV footage looks like, I hate it. But in my case I can render the final video as "ProRes" and it looks a little better.
If the DV footage looks good on the tape but bad in Final Cut Pro, it may be worth going to your sequence and control+click to select "sequence settings". There, select animation codec under the render settings. Render a portion (this will make a HUGE render file -but you can always delete it) and see if it looks any different.
My logic is probably totally off because I am basing it on HDV and not DV, but this would only take a minute to try.

Pete Cofrancesco
November 14th, 2008, 11:58 AM
Where is the "color shift"? If you are referring to the intense reds, that can be expected. If you exported a still from the timeline instead of a screen grab from the FCP desktop, I think you would find the image to be sharp.

FCP and many other NLEs downgrade a DV file's image on the computer screen to reduce processor resources while playing back. If you played back thru firewire to the camera then to the monitor, the image should be sharp.
I agree with Williams assessment.

William Hohauser
November 14th, 2008, 04:04 PM
The camera is possibly out of focus. Clubs can be horrendous places to shoot in. The intense red lighting which you find in many clubs can cause certain cameras (usually cheaper ones, single or 3-chip, like the ones I own) to smudge the image where the red light is most intense. This is an effect from the actual electro-magnetic wavelengths of red light on the camera electronics and something I am not qualified to explain any further. I can say that it was a lot worse back in the days of tube cameras. Intense blue can have a similar effect as can other colors but red is the worst. There's almost no way to get a well focused image without reducing the intensity of the red light.

The computer monitor is never the best place to make an assessment of your final video image. Always try to get the image out to a television monitor. Transcoding to ProRes or the humungous Animation codec will not change the sharpness of the image.

Let's give a frame in each codec a random value of units.
DV = 20, HDV = 100, ProRes = 400 and Animation codec = 1000 (these numbers are not real, so forget them after this!)
Transcoding HDV to Animation will give you a file where a single frame goes like this: 111111111122222222223333333333 until 100 is reached, while a file natively in the Animation codec would be 1 thru 30 in the same amount of space that only 3 units of info in HDV came across.

If this is clear, you can see that no information is gained at all, you've just repeated the information proportionately until the larger space is filled. However your computer behaves differently with each codec so you can actually get better results with a larger file if the computer has to do less work streaming the pixels to the computer screen. HDV is a lot of work for your Mac while the larger ProRes is less. That's why I use ProRes for complex projects but stick with HDV for simple ones.