FCP5 High Precision YUV?

[Jon Fordham]

I'm in the process of cutting a new reel with my new PowerBook and FCP5. Being a cinematographer, my post experience is limited to color correction and some basic FCP editing for my reels. So I'm not super experienced with too many hows and whys of some settings within the app.

I've noticed that FCP5 has a variety of settings for YUV, white, super white etc. In the past I've always had my settings at YUV Super White. But I've noticed in FCP5 that the default DV setting is not at YUV Super White and that there exist a new "High Precision" YUV designation. I say new because I've been working with an ancient version of FCP and an even older G4!

I'm wondering if anyone can tell me why I should, or should not be using the High Precision YUV setting. My thoughts are that the High Precision YUV Super White setting is preferable, and simply takes longer to render any changes. Since I'm only cutting my personal DP reel, and the only rendering that may be needed is some minor color correction, I can deal with longer render times.

I'm familiar with the difference between white and super white. But can anybody tell me if there is an actual difference in the quality or functionality of FCP5's High Precision YUV Super White setting? Or if there is any reason I should, or should not be using it?

[Glenn Chan]

White versus super-white as far as I know:
In digital video, blacks are supposed to be at 16 16 16 and whites at 235 235 235 (RGB values, converted from YUV).
Values above and below that are "illegal" colors and will cause buzzing in audio in composite connections or in broadcast (they'll probably just get clipped).

If you render with the white setting, Final Cut will clip those values for you. This may not be helpful. If Final Cut doesn't have to render something, it won't clip illegal colors. So if you have two clips and a cross dissolve, illegal whites will be clipped during the cross dissolve but not in the clips before/after it.
So... just use superwhite.
If broadcast-safe colors are important, nest your project and apply the BS safe filter to that.

Adam Wilt's site has a better explanation of that.
http://www.adamwilt.com/DV-FAQ-editing.html

2- In high precision YUV rendering, FCP uses 32-bit floating point numbers instead of 8-bit numbers for rendering. This gets rid of problems from rounding error and clipping from filter to filter.

For basic color correction, it shouldn't be necessary.

[Graeme Nattress]

I've not managed to produce a "test" in FCP that shows any benefit to so called "High Precision YUV" rendering, and the only way I know to tell if it's turned on is slow rendering. I'd do a test on an "extreme" colour correction and see if you can see the difference. I'm betting you can't.

As for the white / super white setting, it's only used for the import of still images into FCP and how their white gets mapped. It doesn't seem to effect renders at all.

Graeme