216 NONLINEAR EDITING
During operation Desert Storm we learned a new term, "fog of war," where information, sometimes conflicting, sometimes inaccurate would lead to no certain conclusion. Nonlinear editing is in a "fog of change" where wonderful things are happening, even more wonderful things are in the protype stage, but the real products are buried in a cacophony of conflicting equipment specifications, purposefully omitted specifications, and manufacturers' hype.
At this moment, here is what appears to be true: there are three kinds of nonlinear editing systems being sold:
1. Nonlinear off-line editors. These consist of software plus a hardware device that allows your computer to drive your VCRs. You would time code your tapes, view them, log the good scenes, decide which scenes to use, type the start/stop points into your computer, and have the computer perform the edits. By reading through the list, it will position your recorder and player at the right spot to record the first scene, then go to the next line of data on the edit list and perform that edit, and continue till the job is done. Sometimes the machine will stop and tell you to change videocassettes in the player if your raw material is on more than one tape. Other than that, almost everything is automatic. The low-priced (under $500) systems are now antiques because most everyone edits inside computers (NLEs or non-linear editors). The higher-priced systems are used for high definition editing where good editors (computer hardware and software) are quite expensive. These systems allow you to do dissolves or effects. This means that you will need three VCRs (most likely HD -- high definition) and a switcher or special effects generator to perform the wipes and dissolves.
Still, all you are getting is a program that allows you to list what you want to have happen. All the work is still done by external boxes (VCRs and switchers), triggered by the computer program as it runs.
A few of the higher end systems include the special effects generator on a circuit board that fits into your computer. Thus, the edit list drives the editing VCRs and players who pass their signals through this circuit which performs dissolves, wipes, and other special effects per instructions you typed into the edit list. At this point, we are starting to merge into the next catagory.
2. Nonlinear rough-cut editors. These software/hardware configurations do the above plus one other thing; they allow you to record your material from your video players onto your hard disk to view and edit quickly, without waiting for tapes to wind and rewind. In order to store so much material on the hard disk and manipulate it in real time, the audio and video signal had to be severely compressed, degrading the quality. Still the quality of this PROXY video is good enough for you to select scenes, sound, and edit together your production for the client to review. Once the images are digitized, it is a fairly simple matter to include effects in your transitions from scene to scene, and also to perform A/B/C rolls. When finished editing, you have two things:
a) a low quality rendition of your program, including all effects.
b) A detailed edit list showing all the start and stop points, all character generated titles, audio clips and mixes, and all effects.
Once you and your client have "perfected" your rough cut, you can:
a) Play the rough cut back onto video tape and give it to the client if a low quality production is all that is needed.
b) Set up your VCRs, special effects box, and other sources and allow the computer to carry out the edits on the list. This way your picture quality is as good as your master tapes would allow.
c) Copy your production to a CD or stream it to the internet. The reduced quality of the image matches the reduced quality of these two media.
d) Have the computer, using its edit decision list, activate the video tape machines to play ONLY the material needed for the show, and edit the material internally, automatically.
The above method is used frequently for HD editing.
A moment ago I mentioned the low quality compressed image used in the rough cut. This image can range in quality from 1/4 as good as VHS, up to DV depending upon the speed and power of the computer, the quality of the compression scheme, and the speed and size of the hard dives. There are many variables and lots of fog. If you have lots of raw material to digitize, you may need giant hard drives. If you compress the material at a higher ratio, the quality goes down but requires less space on your hard drives. Now the question becomes, what can you and your clients stand to look at? At the top end of the scale, the computers are fast, the compression ratio is small (damaging the picture very little), the hard drives are fast and big, and the costs are high. Now we are merging into the next catagory.
3. Nonlinear on-line editors. These are entire studios in a box. You play your original video tape (whatever format) into the box which compresses the signal lightly (whatever amount you can stand, taking into consideration how large and how many disk drives you have in the system), make your edits while viewing a fairly decent picture from your computer screen (or second video monitor while the computer menu remains on the computer screen), perform all your audio mixes, video effects, titling, A/B rolls, whatever, on your computer, and then after review with the client, play the results back out onto tape. Although these machines can perform a list managed edit (repeating the whole process with a VCR recording directly from video players), the on line scenario is normally a one-step process; whatever comes out of the computer is your final product. These are popular for standard definition editing.
It is hard to manufacture an on-line nonlinear video editor for HD. SD NLEs are within the realm of fairly generic computers costing under $2000. For HD, because of the increased data associated with the detailed pictures, the computer has to be very fast, the compression must be very clean, and the hard drives very big and also fast. Such editors cost $10,000 to $30,000. There is a lot of competition between manufactures as they invent faster, cleaner compression techniques and faster drives.
If you are planning to enter the world of nonlinear on-line editing, here are three important things to consider:
a) If you are doing more than one job at a time, you need removable media so that you can easily remove several gigabytes of video footage pertaining to one project and replace it with several gigabytes of another project, perhaps picking up in the middle of the edit.
b) If working in higher end formats like Betacam or digital, on-line editors can save you money. Instead of buying four professional editing video machines (one recorder and three A/B/C roll players) at maybe $12,000+, a switcher/special effects generator plus your acquisition camcorder for another $12,000, you could simply buy the acquisition recorder, using it to play your raw footage into the computer. The manuipulations are done in the computer and played back out into your camcorder (unless the show runs longer than your camcorder will accept, in which case you will need a second VCR to store the whole show on tape). The cost of buying three to four expensive VCRs plus a switcher go into buying the fancy computer and drives. Which is the better deal depends on the cost of the recorders and the quality of the final result from your chosen nonlinear on-line editor.
c) Check carefully to see that your on-line system is providing 60 fields per second of video not 30 fields per second, doubled. Some systems, in order to compress the image, record only half the fields, then double them up on playback. The degradation is hardly noticeable, but can be recognized by the discerning viewer as jerky motion. This jerkiness would not be noticed by the common home viewer, and therefore wouldn't bother the wedding videographer or small industrial videographer, but would be unsatisfactory for broadcast, commercial, and high-end industrial users. Because computer chips, compression schemes, optical and magnetic hard drives, and other electronic devices are proliferating, I predict more fog. Don't wait for the fog to ever lift completely or you'll never buy anything. I believe, however, that this is not the best time to purchase HD nonlinear editing equipment at the high end ($15,000+). SD NLEs cost $2000 for the computer and $100-500 for the software. Bigger, faster computers will allow effects to be performed in real time, rather than your having to wait for them to render. This pleasure will raise the cost of the computer to about $3000.
Improvements are blossoming too quickly and great things are around the corner. Manuafacturers are promising fabulous low-priced optical/magnetic hard drives that are in the prototype stage. Engineers are describing new compression schemes that may bring high quality on-line HD nonlinear editing down to the $6,000 area within two years. If you plan to jump into the on-line nonlinear world, make sure the manufacturer has included an upgrade path allowing you to take advantage of speedier, better technologies when they come available ---without throwing away your entire system.
| About the author | About Today's Video 4th. ed. | Return home |