Apple Pro Training Series. Optimizing Your Final Cut Pro System. A Technical Guide to Real-World Post-Production

FCP's internal filters and tools are capable of a lot, but it's useful to have external processors to fix, route, and condition signals before you capture them. They add capability and flexibility when working outside of FCP, too.

Proc Amps

Proc amps, short for processing amplifiers, are used to correct brightness and color problems in video images. They typically have four controls: DC Level or Pedestal to adjust the black level of the image; Gain or Contrast to adjust the overall strength of the video signal; Color or Saturation to tweak color strength; and Hue or Phase to correct problems in hue. (Make the faces less green! No, make the faces less purple!)

Fixing the image before it comes into FCP means that you'll have full latitude to tweak it as needed during editing; if you capture a distorted image, you'll use up that latitude simply fixing what's broken, and you may have irreparably lost details (typically in highlights or shadows) that could have been saved prior to capture.

Proc amps also regenerate clean sync pulses and colorburst (if the signal is composite or Y/C) to ensure clean captures, which is very useful if the original signal has been degraded due to multiple generations of dubbing.

Some also allow adjusting Y/C delay: in color-under formats, chroma can drift sideways compared to luma, and it drops down a scanline with every generation of VHS or Video8 dubbing.

Proc amps may also offer noise-reduction options and image sharpening options. These can be useful at times, but must be used with care to avoid degrading the image more than improving it.

TBCs

Timebase correctors compensate for the horizontal jitter and timebase instability that analog formats suffer from. TBCs are by nature built into all digital VTRs, and many analog ones (Betacam especially), but are often absent in consumer and industrial ¾", VHS, and Video8 decks. If you work with analog formats and your playback decks don't have TBCs built in, a separate, stand-alone TBC can be a lifesaver.

Most TBCs offer at least the basic proc amp controls, so you can use them to correct and clean up images as well as stabilize them. Many provide transcoding capabilities: they can capture from one signal format, such as composite, and output composite, Y/C, and component simultaneously.

Audio Mixers

Most editors keep a small audio mixing board beside their FCP systems. The Mac's output, as well as the output of CD players, VTRs, and other sound sources is routed through the mixer, which provides a convenient, centralized volume control for all these devices. A mixer also comes in handy for performing voice-overs, dubbing between VTRs, and performing various other sound-adjusting tasks. The mixer's outputs are fed to the monitor speakers, headphones, and even back into the Mac's audio input as required.

Sync and Blackburst Generators

Video equipment needs to be synchronized to work together; anyone putting together a multichannel video studio or A/B roll linear editing suite has to provide house sync to all VTRs to ensure they run in lockstep. But even in a single VTR FCP system, you may need to provide a reference signal to the VTR to ensure proper operation; Betacam decks especially seem to misbehave unless they're provided a stable sync signal on their reference inputs.

Generally speaking, you'll need reference run to your deck and to your Mac if you're using RS-422 control, even for decks that work fine without reference. RS-422 protocol works best when its commands are sent coincident with the start of each field, and the only way to assure this is for both Mac and deck to be running in sync. You usually won't see frame-accurate captures and edits to tape if you're missing a common reference signal.

Some capture cards provide a reference signal output; others need reference input.

Reference is a composite signal, containing video (commonly just black), colorburst, and sync, hence the term VBS: video, burst, and sync. Because the signal has a black picture and colorburst, you'll often see sync generators called blackburst generators. You'll also see the term genlock used for blackburst reference.

Even HD VTRs accept an SDTV composite reference signal, although some also have inputs for HD tri-level sync, which requires its own generator.

No consumer decks or camcorders have reference inputs, nor do many DV and DVCAM decks. But as you move up the price scale, more decks have reference connectors, and many of them need reference to work properly. Decks that need reference, but aren't getting it, exhibit a variety of symptoms: black bars rolling through the picture, vertical jumps or rolls in the picture, and erratic capture and recording performance among them.

Sync, blackburst, or reference generators are small boxes that do nothing in life other than put out stable, clean, black video, for the purpose of synchronizing and stabilizing devices that need it.

Some FCP capture cards generate their own sync signals to feed to a VTR while others have a genlock input to receive the same signal being fed to the VCR by an external sync generator.

Tip

If you don't have a reference generator in your DV-oriented shop and you rent a Betacam or other high-end deck for a job, you can use a DV camera with the lens capped as your reference source. There's nothing magical about reference: any stable source of black video will work.

Distribution Amps

You may need to send a video or audio signal to multiple places at once: video and audio to a rack of VHS machines for dubbing, or blackburst to all the VTRs in your shop, for instance. Distribution amps (DAs) simply amplify and replicate one signal across multiple outputs, allowing you to feed all those devices from one source.

Patch Panels and Routing Switchers

If you wire up your equipment in one configuration and never change it, you won't need patch panels or routing switchers. But most of us change things around from time to time, varying which VTR is captured from or which video source is displayed on a monitor. Patch panels and routing switchers let you repatch or reroute signals easily, without having to crawl behind racks or desks and fiddle with the back panels of the gear.

Patch panels are passive devices with no active electronics. An array of jacks presents the inputs and outputs of the equipment wired to it, and you make connections between two jacks with a patch cord. Some jacks are self-normaling: When no cord is plugged in, the jack on top is connected internally to the jack below it, so that the panel with all cords removed is connected in a "normal" configuration.

Switchers are active devices that amplify and route signals electronically. They connect sources to destinations at the push of a button. Most of them also serve as DAs; one input can be sent to multiple outputs.

Both devices come in a variety of formatsaudio, analog video, digital videoand connection types: BNCs, RCAs, even FireWire.

Purists may prefer the unadulterated signal path of the patch panel, whereas others prefer the convenience and flexibility of switchers.