Edit Suite: An Off-line On-line Outline

Editing at home on your PC can save you time and money, but there are limitations.

Professional editors distinguish between "offline" and "online" video editing and now you can too. Before you mutter "Whoopee," and flip to the mail order pages, consider what offline editing can do for you.

In a nutshell, this technique can deliver much of the power of digital post-production with zero investment in expensive hardware and software. For the price of a software package that typically costs less than $200 you can enjoy many of the benefits of nonlinear digital editing.

To see how this works you need to understand what "offline" and "online" mean in their classic sense and how the newer digital off- and online procedures are slightly but significantly different.

Traditional On- and Offline
In its classic form, "online" editing is performed with the original camera footage in a full-scale post production facility, using a suite full of hardware that costs 100 grand to buy and therefore, hundreds of bucks per hour to rent.

Because of these costs, performing the entire post production process online would be ruinously expensive. Hence, "offline" editing: assembling the video and audio elements from duplicate footage in your home or office and using high-rent facilities only to quickly conform the original to the edited copy.

Heres how the process works: the original high-quality camera footage is copied to a work tape, complete with time code that identifies every single frame of material. From here on, all video and audio editing is performed with this work tape. As you build your show, your computer keeps track of the start and end frames of every shot, plus all the audio tracks, titles, effects, and so-on, in an edit decision list (EDL).

When youre ready for online assembly you take this EDL to a post production house, along with your original footage. There, another computer consults the EDL to semi-automatically create a frame-for-frame edited master tape from the original material in a high quality format. Even with the inevitable last minute changes, a half hour show that took 80 hours of offline work may require as little as four to six hours online to finish.

Since the offline copy is as much as 95% expensive than the online, its easy to see why offline/online editing has been exclusive to professional production.

That, then, is off- and online editing in the traditional form: essential to high-end professionals but way out of reach to prosumer video makers –until now.

Comes the Revolution
Now theres a new form of offline, and to understand what it means to you, we need to summarize desktop digital video editing.

In digital editing you start by making high-quality digital versions of the shots you want and store them on a fast computer hard drive. Then you assemble your show, typically, by placing graphic symbols that represent those shots (and audio clips and effects etc.) on a time line on your computer screen.

As you complete each sequence, you make a preview version of it. By creating low-quality assembly of the program, you are able to check timing, effects, titles, and so-forth. When youre done, you instruct the computer to use the time line as a blueprint for re-assembling the identical program, using the high-quality digital originals of the shots.

Hmm; you assemble your program from low-quality copies of your shots. That sounds suspiciously like classical offline editing. Then the computer automatically creates an identical final version from the high quality digital originals by using the time line as an edit decision list. In doing this it is, in effect, working online, isnt it?

You bet it is! Full scale digital editing replicates the traditional offline/online work sequence. The sole difference is that the "high quality originals" are actually digital copies of the taped camera footage. The wonder of desktop video is that you can do post house quality work without having to go outside and pay through the honker to do so.

Ah, but theres still no free lunch. Though you can cobble together hobbyist-level digital systems (or single-purpose stand alone boxes) for as little as $7000, professional-quality programs of any length demand setups costing double that; and for full-time work-for-hire, a good system can run you 20 big ones and up. Way up.

Offline for the Rest of Us
To address the cost problem, mighty minds at several post production equipment companies have studied the situation and concluded:

  • Most of the killer costs in digital desktop involve creating, accessing, processing and storing high quality digital copies of original footage.

  • Yet, traditional studio online systems dont need digital footage because they work directly with the original camera tapes.

So why not bring the traditional approach from the studio to the desktop, where it will work just fine on any plain vanilla Pentium system?

Thats just what theyre starting to do. Were beginning to see editing systems that make only low-quality digital sound and picture work prints. Because of the small image size, slow frame rate, and aggressive data compression, the resulting files are so compact that a poky IDE hard drive can handle them in real time. This easily allows for storage of two to four hours of material (though at quarter-screen size and 15 frames per second, its good enough for Webcasting).

Using these low-rent copies, you can assemble and trim video shots, add titles and digital effects (both generated by the software supplied) and lay down and mix multiple audio tracks. Because you can see and hear a full motion version of your show at all times, you can fine-tune your work on the fly.

And when youve massaged everything to your satisfaction, just tell the program to make a final assembly. Using your edited work file, it finds the shots on the original tape(s) and copies them to a second generation edited master tape complete with titles, effects, and mixed audio.

So Whats the Catch?
First, the system automatically replicates your low-quality work print by controlling both the source deck (or camcorder) and the record deck. To do this accurately, it needs true time code. Addressing your tape with time code is the only way to reliably identify shots and keep track of where you are on a tape.

The problem is that most consumer equipment uses a control track, not time code. Control track carries a signal only once for every 30 frames, and its a generic pulse that does not include any kind of address.

Computerized edit control systems have long used ingenious strategies to get around the limits of control track editing. First, they use the computers clock to subdivide the one-second intervals that are between pulses into 30 parts. Each part corresponding to one video frame. To keep these virtual numbers the same each time the tape is used, older systems require you to rewind and restart it every time you insert it into a VCR (a nightmare with multi-tape shows).

Newer systems identify and memorize the visual appearance of selected frames on a new tape, recording the virtual address of every one. When the tape is replayed the system senses each of these reference frames and corrects its software "counter" to match the frames assigned address.

All too often these systems dont work reliably. At best, edit points may be off by several frames. At worst, you look on in dismay as an apparently slap-happy system auto-assembles a program that has little or nothing to do with the offline original.

Youll have lots of time to look on, too, because the second drawback is the agonizingly slow speed of the auto assembly process. True digital auto-assembly can also take hours, but at least you dont have to sit there swapping source tapes, since all the original material is on the hard drive.

The last big catch involves the PC platform and the Windows 95 operating system. No matter what they tell ya, folks, all entry-level media editing systems are prone to conflicts, lockups, and frustrating glitches.

The bottom line: slow assembly and computer frustrations are bearable if you can work with true time code. the transitions, the audio editing, the titling programs that you will be using with time code alone are worth more than the cost of the system. But if youre still plodding along with control track accuracy, think twice before investing.

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