pretending to be pro: Proc Amp

The graphic on the left shows the working of FCP7's Proc Amp as "video" is set to -1 or +1. The graphic on the right shows how a Proc Amp should function correspondingly.

German has a good word, "Besserwisser" (literally, better knower), for Apple's attitude about technology. FCP7's User Manual says Proc Amp "simulates the controls available on a composite video processing amplifier." It says "the Video slider lets you adjust the white level". Yes it does do that, but not as you'd expect, not as gain. The Glossary entry for "gain" can only describe its adjustment to white level.

There is use for a white-lowering Y' filter that doesn't clamp sharply but rolls off smoothly. FCP7's Proc Amp with "video" set negative does that job nicely. Apple should have named this "luma limiter" and put it somewhere else, because a Proc Amp is expected to have linear controls. Hey, gain adjustment has use too. Even Apple's new lexicon can't explain its "video" filter's positive settings. The +1 curve makes no sense except for undoing the -1 curve. Also Apple muffed the +1 curve, making it jump up to 254 Y' out from 235 Y' out.

Gain is linear by definition. Some Proc Amps call this Y' control "gain" while other Proc Amps call it "video", but the function is the same (except Apple's). Digital video is too technologically fragile for undisciplined Besserwissers. Engineering foolery in one place can disrupt the whole. FCP7's shoddy image control filters show that the 'P' in 'FCP' was never deserved.

Dennis Couzin
Berlin, Germany

It's pro, but it's for offline, not for finishing. So what I like to get at the end of the day is edit decisions, either as an EDL or a QT or a tape. I really only see the color correction tools in FCP as good for proof of concept, of course, if it works for you, use it by all means. For color correction work, I suggest looking at Apple Color in FCS, or the DaVinci Resolve.



www.strypesinpost.com

well, a fair few people do use FCP to finish. (Walter Biscardi comes to mind, and Michael Gissing.)
of course most of them would have adopted a Color workflow a few years ago.

i've graded and finished a few low-budget (non-Pro) projects myself in FCP,
but i've never used a Proc Amp!



nick

Not only professional tools find good use in a professional's toolkit. I'm reminded of the humble orange stick favored by camera mechanics. strypes describes an intelligent professional use of FCP: it provides the cut; it provides crude preview of the finishing; specialists using specialized software then redo the finishing. It can be debated whether all-in-one software is possible or desirable for video editing.

There's a distinction between providing limited tools, such as FCP's color correction tools compared to Color's, and providing shoddy tools, such as FCP's gamma correction filter and Proc Amp. The latter are very basic image control filters which require no more code to write right than to write wrong.

Finally consider Apple's intentions. The User Manual boasts that Proc Amp "works in 32-bit floating point if your sequence is set for high-precision rendering." So Proc Amp is a high precision parody of a proc amp.

Dennis Couzin
Berlin, Germany

Can we at least agree the Broadcast Safe filter works??? I like how it rounds the luma rather than clipping.
But now after reading Dennis I have fear and doubt... ;-)

I had Mark Steele over to my hovel years ago, to check out FCP. Mark mastered all the national programming coming out of
WGBH, PBS Boston.

He went right to the Proc Amp. Looking at the Trinitron I had set up, he seemed impressed with the control.
Of course, he was going by eye, not graph.

- Loren

Today's FCP 7 keytip:
Advance to next/previous keyframes in a clip with Shift/Option-K !

Your Final Cut Studio KeyGuide™ Power Pack
with FCP7 KeyGuide --
now available at KeyGuide Central.
www.neotrondesign.com

Loren: the luma control on the FCP broadcast safe filter is described here.

Let's compare the visual difference between the FCP7 Proc Amp video control and a proper gain control. Consider the -1 setting on each. Assume the monitor has gamma 2.2 and use CIE L* as the measure of visual lightness. It takes about 2 L* units to make noticeable change. The FCP7 Proc Amp reduces the Y'=235 white by 16.4 L* units while the gain control reduces it by 18.0 L* units. A Y'=170 light grey is reduced by 6.4 L* units and 14.2 L* units respectively. A Y'=74 dark grey is reduced by 0.5 L* units and 7.7 L* units respectively. Someone looking at just the white will believe FCP7 Proc Amp behaves like a proc amp. Someone looking at the whole picture will see a significant difference.

Dennis Couzin
Berlin, Germany