Desktop Video: Linear vs. nonlinear Video

There's no doubt about it--the good old days of linear editing are numbered. Digital video is like a bullet train hurtling down the track, closing in quickly on the complacent caboose of analog video.

But don't toss out your analog equipment just yet. The digital technology that is available is truly astonishing, but for the money you'll spend to get the holy grail of "broadcast quality" video, you could buy your own pullman coach instead. Not to mention that managing only a couple of minutes of uncompressed digital video can tax even the best of home computers. Nevertheless, it's clear that nonlinear video has a lot to offer, and it's getting better and cheaper every day.

If you're happy with VHS quality (and millions of video store fans can't be all wrong), then you'll be happy with today's digital video. If your target medium is the computer, then you have no choice--you must digitize your video. And if you need broadcast quality video, there are some affordable choices. This article will begin with an exploration of this fascinating new world, and end with a step-by-step tour through a typical nonlinear editing project.

Linear Editing--The Good Old Days

In case you've managed to miss it, linear editing involves endless days and nights of listening to the hum of a tape deck while it rewinds and fast-forwards to a choice cut. Then, after carefully cueing the exact frame, you lay down a miserly ten-second clip or so. Cut after cut after cut. If you're a fan of Chinese water torture, you'll simply love waiting on a tape deck.

When you get done with this mind-numbing task, you can feel justifiable pride in your masterpiece. It's a one-of-a-kind, second generation videotape you can use for duplication. That's usually when your client asks you to insert just one tiny little scene near the beginning of the video. Guess what? You get to start all over again!

If you were lucky enough to work with an Edit Decision List (EDL), then you can insert the time code for the new clip and proceed more or less automatically. I say more or less, because if you have source on more than one tape, you still need to pop them in and out when needed. Nevertheless, an EDL is a big improvement in your quality of life, and it's one of the first kind acts that personal computers brought into the video world.

But with the advent of computerized nonlinear editing, the tedium has been completely wrung out of the editing procedure.

The secret to this magic: digitize the video. Once you do this, you can edit it on your computer, using software like Premiere (Adobe), VideoFusion (VideoFusion) or After Effects (CoSA). Since all the access on a hard disk is virtually instantaneous, you never need to wait while assembling clips into your finished opus.

Nonlinear editing is a loose term, but there are three basic outputs: digital video for multimedia, EDLs and videotape. Here's a quick look at this diverse trio:

Nonlinear for Multimedia

Multimedia is a buzzword that refers to a wide range of computer applications, usually on CD- ROM, that incorporate audio and video into the final product.

Because the final product will play on a computer, nonlinear editing is perfect for multimedia. Since you have to digitize the video anyways, it's only natural to edit in the digital domain. The video window is usually small (due to CD-ROM constraints), so it doesn't take the most expensive equipment to capture video. Finally, the output stays digital, so you don't need to convert it back to NTSC.

A typical setup involves a PC with a capture card and at least a gigabyte of hard drive space to hold the captured video. With some good editing software and a special effects program or two, you can generate a ton of multimedia. When you finish editing your digital extravaganza, you can send your hard drive to a service bureau to have your CD-ROM mastered. From this "one-off," you can have a service bureau duplicate the final copies.

A major tip for this kind of work: capture and keep your video in the highest resolution you can until the bitter end. If you compress your video more than once to save space, the quality will suffer dramatically. The degradation is not dissimilar to the loss of resolution when you copy a videotape, except that digital video usually becomes blocky rather than blurry.

The downside of this technique is that it takes far more data to store your video in the uncompressed (read uncompromised) form. You can work around this drawback by editing and compositing your project in segments. After you have completely edited each segment, compress it. Backup the compressed footage and clear the rest of the disk for the next segment. A pain, but that's the tradeoff if you want quality on the cheap. Of course, you can always spring for a bigger hard disk to simplify your life. Just remember: recompressing is the single most common reason for crummy-looking digital video. Don't be guilty of this avoidable sin.

Nonlinear for an Edit Decision List

What if you need quality video but can't afford the expensive hardware and massive drives for full-screen, full-motion capture? You should consider using the Edit Decision List provided by programs like Premiere and After Effects. This only uses your captured video for putting together the EDL. You do this by digitizing, previewing and making a mock-up edit of your work. You can edit till you are happy with your production, then take the EDL and the source video to a service bureau to put the footage together. Since you are going straight from your original source tapes to the master, you will get optimal video quality.

Be aware that you won't be able to include all of the fancy effects that the computer program may offer. Check with your bureau to see what they have available.

Nonlinear for Video

If you're willing to spend a little more money, you can capture full-frame video. For the computer community, that turns out to be 640x480 pixels of resolution. With a monitor's aspect ratio, that resolution results in square pixels, which make programmers very happy.

Each pixel typically takes three bytes to store on the hard drive: one for each of the red, green and blue color components. Since each byte is eight bits, this method allows 256 variations for each component (8 bits = 256 values). That doesn't seem like a lot, but in combination with the other components, it can produce over 16 million colors. So each screen is 640 x 480 x 3 = 921600 bytes. Call it a megabyte.

One second of video has 30 frames, so you have to pipe 30 megabytes per second into your hard disk! The average PC bus (its internal data pathways) don't go anywhere near that fast. So how do you squeeze the genie into the bottle? You need to compress on the fly, and bring the data down to manageable rates, on the order of one to three megabytes per second. Most top-of-the line PCs can keep up with that.

Even compressed to less than five percent of its original size, digital video really eats up the disk space. You'll probably end up looking at RAIDs (Redundant Arrays of Inexpensive Drives) before too long. Don't think you're going to put together a movie-of-the-week on a system like this, but you can do a lot of effects and short subjects. Commercials and music videos, especially if they have a lot of computer effects or animation, are ideal for these nonlinear systems.

If you can push the data rates up toward the 10-megabyte-per-second range, you have entered the fabled realm of broadcast video. This data rate is comparable to D1 digital tape and the meager compression is usually lossless, resulting in excellent video. Of course it takes more expensive computers and more and faster hard drives to pull it off, but bona-fide PC-based, broadcast-quality nonlinear editing is finally a reality. Some of the contenders in this arena are Media Composer (Avid), VideoCube (ImMIX) and Media 100 (Data Translation).

Digital systems really shine when it comes to complicated compositing. You can stack video layers up to your eyeballs without losing quality. Unlike film and analog video, you can copy digital video with perfect accuracy as many times as you want. And it's easy to pull off blue-screen effects (chroma keying) with digital tools.

These machines are still new and have room for improvement. But they have already shaken up the industry, because even as they add capabilities and save considerable time, they cost about half the price of their analog counterparts.

Step by Step with a Wedding Video

Let's put these tools to work on a hypothetical wedding video. First you need to preview your footage to select the good cuts. When you've picked out the good stuff, you're ready to digitize.

No matter what kind of capture card you have, it will have a video jack on it so you can route your video into the computer. Some popular cards are made by Truevision, Radius, Fast and Matrox. The better cards have S-video inputs. If you shoot in S-VHS or Hi8, you should take advantage of the superior signal that this connector provides. Otherwise, you will have to content yourself with a standard composite NTSC jack.

If you have a rich, indulgent uncle, he might buy you an upscale capture card with component RGB or YUV input. But for our example, I'll assume that you're not shooting Bill Gates's wedding in IMAX, so NTSC will do just fine.

Fire up your capture software (usually included with the capture card) and grab just the video you need. Overkill is deadly here, as hard disk space is at a premium.

If you want to go back out to video from digital, you'll need to capture at the highest resolution and frame rates you can squeeze out of your machine. If you just need an EDL for later editing, you don't need to worry much about the quality. If you are going to make a CD-ROM (don't laugh; as Generation X starts to take the matrimonial plunge, their preferred media is often CD-ROM), then capture at the maximum size your CD-ROM player can handle, usually around 320x240.

Adjust the color and saturation at this input stage. Yes, you can do this later, but the results never seem quite as good. Remember to keep all your video in its least-compressed form (unless you just need an EDL). If you've got the hard drive space, this will give you better quality.

Editing: the Fun Part

Now for the fun part. Using a program like Premiere, you can edit the ceremony. Most editing programs have similar functions, so for simplicity, I'll use Premiere for this example.

Premiere lets you load recorded clips into a project window. You then identify the clips by a shrunken image taken from the clip called a "thumbnail." You can single-frame through the clips and select the exact in and out points for each. To assemble your video, you just drag the thumbnails with the mouse and put them into the construction window, one after another. It really couldn't be easier.

Once you have the pieces put together, you can add a little background music. With a sound card, record the music you want as a digital file (a .WAV or .AIF file), then load it into your project as a sound clip and drag it into the sound track.

Even after you assemble your clips in the construction window, you can still edit them. There are two ways to accomplish this: rolling and rippling. A rolling edit extends a clip into neighboring clips, rolling over them. Thus, if you extend the end of one clip by three frames, it will automatically cut off the first three frames of the next clip to compensate. A rippling edit, on the other hand, causes any changes in a clip to move like a wave through the rest of the movie. If you lengthen a clip by three frames, the following clips all move back in time by that amount. If you have music or sound effects that must play in synch with particular moments in your video, you must be careful to use the right tool.

Don't forget the special effects! One of the best reasons to be in the digital world is to make use of the infinite effects available. Use the transition channel to dissolve the kiss at the altar into the kiss after the cake-cutting. Start out the video with a rotation effect, spinning the wedding party out of a black hole. Take a picture of the wedding bouquet and use it to perform a vertical wipe.

Finally, add titles to your work. You're almost done.

Video Output

If your target is a CD-ROM, then compress the movie to the proper data rate. These rates are 150 kilobytes per sec (kps) for single-speed, 300 kps for double-speed players.

If you want to go out to video, compress only enough for your equipment to play it back in real-time off the hard disk. Then it's time to run it through a video output card. If you were smart, you bought a capture card that could also output video, saving yourself time and computer slots.

Whatever your project, nonlinear can be a part of it. There are still some bumps on the tracks, but the nonlinear train shows no signs of stopping. Now is the time to hop on.

All aboard!

Scott Anderson is a software developer, book author and president of a computer graphics development company.

---

DTV News

Scan Lines

Fast Agreement Fast Electronics and Sanyo's Industrial Video division have formed a joint agreement to develop control products for Sanyo's recording systems. The Edit-Pro is the first result of this agreement. This is a complete package that includes Sanyo's GVR-S955 editing recorder and a computer-based timeline editor that offers over 200 digital effects. Further products are in the planning stages.

Digital Video Camera In Japan, Sony announced that they've signed an agreement with Texas Instruments to develop digital video cameras specifically for use with computers. The cameras will use a high-speed chipset developed by Texas Instruments to record video in digital form, eliminating the need to convert analog video signals for DTV use.

Product Menu

Strata StudioPro 1.5 ($1495)

Strata Incorporated

St. George, Utah

(801) 628-5218

StudioPro 1.5, a 3-D application for the Power Macintosh, has gained some recognition for its Hollywood- style effects, which now include explode, shatter, atomize, morph, warp, path extrude and Boolean modeling. StudioPro has been used by many professional video and multimedia productions.

Circle 111 on Reader Service card.

VideoPacker Plus ($375)

Vic Hi-Tech Corp.

El Segundo, California

(310) 643-5193

VideoPacker Plus is a full-motion video/audio capture, storage and playback hardware system that comes complete with AVI and MCI drivers. The unit includes VGA color key and chroma key; bit map overlay; contrast, brightness and saturation adjustments; and a full anti-flicker filter. The VideoPacker Plus comes bundled with VideoStudio software for full-motion capture and editing.

Circle 112 on Reader Service card.

Grand Vision Pro ($349)

Dobbs-Stanford Corp.

Dallas, Texas

(214) 350-4222

This multi-use scan converter works with Macs, PCs and most Powerbooks. The unit converts your computer's output to flicker-free composite or S-video (in either NTSC or PAL). It also comes with a lavalier microphone and built-in pre-amplifier, which makes the Grand Vision Pro ideal for business and education presentations.

Circle 113 on Reader Service card.

ProVtr ($99)

Pipeline Digital

Kaneohe, Hawaii

(808) 235-0335

ProVtr is a software and cable combination for the Macintosh that imports time code for use with Adobe Premiere. It works with most pro VTRs that use 9-pin RS-422 protocols, and also supports most internal time code readers (Sony BVU-800 compatible). A version called ProVtr/Autolog also includes tape logging software for keeping track of shots on a volume of tape.

Circle 114 on Reader Service card.

Nonlinear Editing Price Watch

Nonlinear systems make editing video as simple as cutting and pasting text with a word processor. With nonlinear, editors enjoy true random access to scenes through an intuitive graphical user interface. Thanks to advances in compression technology and plummeting computer prices, nonlinear editing is ready to revolutionize video at all levels.

This table shows the cheapest current system capable of true VHS-quality nonlinear editing. We define VHS quality as any 60 field-per-second, 320 x 480 pixel, full-screen display. Hard-drive prices reflect storage for about 10 minutes of digitized video. Prices are valid at time of writing, and subject to change.

Computer: Macintosh Power Mac 7100, AV card $3349

Capture/display board: Supermac SpigotPower AV $995

Software: VideoFusion Capture Utility (bundled)

RAM: 8 MB upgrade $330

Hard Drive: 1GB SCSI $950

Total $5624

Note: Supermac SpigotPower AV is also capable of 640x480 pixel capture/display at 60 fields per second.

Screen Test

DQ-TimeCoder ($295)

Diaquest Incorporated

1440 San Pablo Avenue

Berkeley, CA 94702

(510) 526-7167

DQ-TimeCoder is a Macintosh-based plug-in product for use with the popular Adobe Premiere editing software package. It provides time code capability as well as source deck control directly from the Adobe interface screen.

The ability to use time code offers many advantages for Adobe Premiere users. If you're using Premiere version 3.0 then DQ-TimeCoder will allow you to log all the shots on a volume of tape and create batch capture lists, functions not possible without time code and machine control.

DQ-TimeCoder will operate with almost any VCR having a 9-pin RS-422 serial port and an internal time code reader. Typical prosumer/industrial examples are the Sony EVO 9800/9850 series Hi8 decks, Panasonic's AG 7650/7750 S-VHS decks, and JVC's BRS 622/822 S-VHS decks.

Once the DQ-Timecoder is installed on your system, it makes a few changes in the way Adobe Premiere operates. When you choose Movie Capture under the Premiere File menu, for example, you'll notice the window has changed appearance. Now, instead of just an image icon and a record button, you will also see a row of machine transport controls along the bottom edge. There's also a time code window and a window that allows capture of in and out points for your scenes. A reel number indicator, auto record selector and log in/out button complete the changes.

To record a movie with time code, simply find and click on the in and out points, check auto record, and click on record. Or, if you have Premiere 3.0 and click on log in/out instead of record, a screen comes up that allows you to capture a batch list (a group of scenes) for later editing.

You can calibrate your Premiere setup for use with DQ-TimeCoder through the record settings menu. During testing, I found that the recommended settings located in the well-written manual worked fine.

This is a simple, easy to use and fair-priced little plug-in. If you're looking for time code accuracy in Adobe Premiere and appreciate the convenience of machine control from your Premiere screen, definitely check out the DQ-TimeCoder.

Ease of Learning: (4)

Ease of use: (4)

Documentation: (4)

Value: (3)

V-Station 3300 for Windows ($995)

Future Video Products, Inc.

28 Argonaut, Suite 140

Aliso Viejo, CA 92656

(714) 770-4416

From the EC1000 to the Editlink systems, Future Video has long been a manufacturer of high quality edit controllers. Now, their Editlink systems have evolved into the V-Station series, which are available in Windows, Mac and Amiga versions.

The V-station series consists of three separate packages offering different levels of price, power and performance. The V-Station 1000 is a cuts-only software and cable package. One step up is the V-Station 2200 cuts-only system which adds a plug-in controller card. Both of these systems offer one GPI trigger.

The V-Station 3300 tested here is Future Video's full-blown A/B roll system complete with serial to LANC breakout box, software (with tutorial), all necessary cables and full documentation. Gone are the graphics boards and titling software of earlier Editlink systems--in their place are three GPI triggers for independent control of external special effects generators (SEGs), titlers and other equipment.

V-Station 3300 offers two ways to edit your videos. You can manually perform individual edits one after the other, or you can create an Edit Decision List (EDL) with multiple events and have the V-Station 3300 automatically assemble your finished tape from scratch. You can also print out the EDL for later use.

The system will work with 5-pin Control-M (Panasonic), Control-L, or professional RS-422 editing protocols. Future Video supplies the cables required at the time of purchase. The V-Station 3300 also recognizes both SMPTE and RCTC time codes for more accurate editing. I tested the system using all Hi8 RCTC capable equipment and constantly got accuracy of +/- 3 frames (and sometimes +/- 1 frame). The system requires any 386 or better CPU with a minimum of 4 megs of RAM and Windows 3.1 or higher.

All edit control is done through the single interface screen which provides separate transport controls for all three tape units. Along the top of the interface are multiple pull-down menus for such tasks as system configuration, full EDL editing, edit trimming and all other basic editing functions.

The EDL window dominates the center of the screen. To make your edit list, you simply use the transport controls to search your tapes, then use the mouse to lift the proper time code numbers and drop them into the EDL window.

A note of caution: the V-Station 3300 requires a special GPI cable (supplied by Future Video) when using Videonics products with the GPI triggers. If you use Videonics equipment, be sure to use it, or you may harm your gear!

I found this system rather easy to use, partially due to the well-written manual and extra documentation included, but also because the interface lends itself to clean, fast work. All the results I obtained were quite satisfying.

As an affordably priced, Windows-based A/B-roll editing system with full features, all I can say about the V-Station 3300 for Windows is--bravo!

Ease of Learning: (4)

Ease of use: (3)

Documentation: (4)

Value: (4)