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Proc Amp Filter in effects???

Posted by Phil 
Proc Amp Filter in effects???
November 07, 2005 05:33AM
Proc Amp? This term has always interested me and although I've checked it up in various FCP books I am none the wiser. What is the proc amp filter? What does it do and how can I use it and what will I achieve? Cheers...Phil
Re: Proc Amp Filter in effects???
November 07, 2005 08:29AM
The Proc Amp filter is an ancient, legacy filter. All of its' function are more than convered by the newer Color Corrector filters. I guess it's still there so people can open projects made with early versions of FCP.
Processing amplifiers are (were?) analog devices that usually provide basic video signalcorrection features, like hue, black level, etc.
All the best



Adolfo Rozenfeld
Buenos Aires - Argentina
www.adolforozenfeld.com
Anonymous User
Re: Proc Amp Filter in effects???
November 07, 2005 10:17AM
It may be legacy, but it does do things differently than the 3-Way Color Corrector. Try the proc amp side by side with the 3WCC and you'll notice slight differences in how things are processed.

I've used them in conjunction with one another to achieve effects I couldn't get with either one alone. Even multiple copies of either one alone.

Proc Amps are part of modern digital switchers, so it's not an old left over analog thing. It's an engineering thing.

Set Up (aka black level) Video Level, Chroma and Phase are the basic building blocks of video processing.

Perhaps one of the more engineering-minded of us might care to chime in on what they really mean, but I know for sure that Phase is not something easily changed with the 3WCC. It's has something to do with the electronic signal, and refers to color, but not hue exactly. This harkens back to the days when decks needed to be timed, and it's been quite awhile for me and my recall ain't what it used to be!!

But these days, it is more of an effect than it is signal corrector, as Adolfo points out. But back in the day, it had much more purpose!

Today's History of Television Lesson (sort of)

;-p

Re: Proc Amp Filter in effects???
November 07, 2005 10:27AM
Hello, Deb!
Please note that when you load the (one way) Color Corrector in the Viewer's Filters tab, the actual property name for Hue is "Phase Shift". So, while the CC filters may not do everything a true Proc Amp does, I believe they pretty much do everything the FCP Proc Amp filter does smiling smiley The controls are different, but it's unlikely something you do with Proc Amp can't be replicated with the CC effects. One of the main goals of the CC filters it to have most controls on one filter, so you eliminate rounding errors and lack of precision induced by the concatenation of several filters. However if, as Deb found, the Proc Amp allows you to do something easily, it's still there, right?
All the best



Adolfo Rozenfeld
Buenos Aires - Argentina
www.adolforozenfeld.com
Re: Proc Amp Filter in effects???
November 07, 2005 10:32AM
Proc amps insured subcarrier (where the color is carried due to the change from Black & White to Color in the earlier days of NTSC) was the right frequency and strength. It could also apply clipping like the Broadcast Safe filter does now. Just don't know what real purpose a proc filter has in the digital relm of an NLE though.



Craig Seeman
[thirdplanetvideo.com]
Anonymous User
Re: Proc Amp Filter in effects???
November 07, 2005 10:32AM
Ahh--see, now I'm learning stuff about FCP!

I never tried 3WCC with the 1WCC! That's a very good point, Adolfo!

Anonymous User
Re: Proc Amp Filter in effects???
November 07, 2005 10:40AM
That's where the legacy part came in, I'd wager.

Early engineers on FCP likely used processing and processing terms familiar in the linear edit suite. I'd guess among other things, this helped with the learning curve. Once FCP "surpassed" what you could do with a switcher, the Proc Amp filter did become obsolete, but they kept it anyhow? I guess now would be a good time to ask, "Why?"

Again, just guessing, but like I said earlier, there are some effects I can't get just right without the Proc Amp, so maybe it does have different math, and it is just different enough to keep around?

Re: Proc Amp Filter in effects???
November 07, 2005 11:11AM
"Once FCP "surpassed" what you could do with a switcher, the Proc Amp filter did become obsolete, but they kept it anyhow? I guess now would be a good time to ask, "Why?""


Mostly, so you can open projects made with those early version of FCP smiling smiley Also, because people used to it may want to keep using what they know.

As I said, the best tool is the one that gives the results you want!

"there are some effects I can't get just right without the Proc Amp, so maybe it does have different math, and it is just different enough to keep around?"

Yes, the math is different. But just in the conventions and parameter ranges. The processing quality is much better in the new ones, I understand.

It's important to notice when to use the One Way and when the Three Way CC. The 3 way CC doesn't have any form of hue/phase manipulation. It's for more precise control of specific areas, which is not what a "Proc Amp" does smiling smiley I believe that, if you give it the time, the One Way CC will become your new Proc Amp!
Also, for many cases of secondary color correction (say you want to change the color of a car) the One Way CC gives you the "big" knob to really tint things, rather than subtly offsetting their color balance smiling smiley

All the best



Adolfo Rozenfeld
Buenos Aires - Argentina
www.adolforozenfeld.com
Greg Kozikowski
Re: Proc Amp Filter in effects???
November 07, 2005 11:41AM
I love it when somebody makes a bad digital copy of an excellent analog tool, and then everybody gathers around it and complains, "Why on earth would you want that?"

A Video Processing Amplifier (Proc Amp) is a tool that can change (as has been suggested) several of the basic characteristics of a television signal. There is always a Proc Amp just ahead of an analog television transmitter to keep "illegal" signals out. Illegal colors and white levels do very nasty, expensive things to a transmitter.

The FCP Proc Amp tool is missing two knobs that I would give anything to have back. Black clip and white clip. It's much more difficult to make a signal "legal" without those.


As far as "Phase" goes. It's only applicable in NTSC and NTSC copy land. It shouldn't do anything in PAL.

The way that they got three color signals to go down one wire (and into your house) back in 1939 was to encode them much like DV encodes color and black and white to go down one bitstream. In order to make it cheap they left out auto color correction. PAL and SECAM which came slightly later, don't have this problem.

You can think of "Phase" as sliding the whole rainbow to the left or right. Reds become blue, blues become, green, greens become.....etc.

You can see the tool in action by putting bars on the timeline and opening up the Scopes tool, Vectorscope. Apply the Proc Amp tool and watch what happens to the scope when you move the phase control.

They're right. You can't get that effect in any other tool.

I sure wish they hadn't left out White Clip.

Koz

Re: Proc Amp Filter in effects???
November 07, 2005 11:45AM
> You can see the tool in action by putting bars on the timeline and opening up
> the Scopes tool, Vectorscope. Apply the Proc Amp tool and watch what happens
> to the scope when you move the phase control.
> They're right. You can't get that effect in any other tool.

Out of curiosity, what's the difference between this phase option and the Phase control in Color Corrector? I've been using Phase - Color Corrector to make alternate versions of graphics for a couple of years.

I always used to wonder what the hell a Proc Amp is, as well. Thanks to everybody for the discussion.
Greg Kozikowski
Re: Proc Amp Filter in effects???
November 07, 2005 10:19PM

<<< Phase control in Color Corrector?>>>

I don't know. I'm back in the shop on Wednesday.

Koz
Max
Re: Proc Amp Filter in effects???
November 09, 2005 04:42PM
Great discussion.

Hey Koz,

Why would you give anything for Black & White clip? What is missing from Broadcast safe filter? Anything to be concerned about?



Max
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