Article: Non-Linear Editing Featuring EMC2

Third draft (Rev C) April 26/93 of nonlinear article featuring EMC2 used for our Israeli project. By Doug Hembruff. 3270 words. This article appeared in VPM (Video Production & Multimedia magazine) in the May 1993 issue #43, pages 18-22.

In the March issue of VPM, I wrote about our field production experiences while shooting a promo video on Christian Group Tourism to Israel. Some readers probably wondered how we would ever make sense of the 43 hours worth of footage that we brought back. It wasn't easy beating that much raw footage into shape, but the task was made possible using an EMC2 (Editing Machines Corporation) nonlinear off-line editing system supplied by David Abbott from Applied Electronics.

Most of my video projects to date have been organized in such a way as to allow them to be processed in a linear fashion. By this I mean that a script was written, approved and narrated, then a shot list drawn up, the video shot, and pictures inserted over the appropriate narration. This linear system worked well enough, but it never really allowed for rippled changes, if the customer changed their mind. It also doesn't allow for incorporation of great shots that you didn't know you were going to get, or shots that were too long or too short for the narration. Linear editing (conventional tape editing) involves a lot of pre-planning if the video is to flow together with an even pace and therefore isn't conducive to the editing of unscripted footage. Linear editing often limits how refined your video can be when you have to fill an exact time frame such as a television time slot.

To explain the difference between linear and nonlinear video editing, I will use the analogy of the manual typewriter and a word processor. If a letter is typed on a manual typewriter and a line is missed or you want to rearrange sentences, the entire letter must be retyped. The ability to make corrections on a manual typewriter is limited to replacing a word or letter with another one of exactly the same size. So it is with conventional linear tape editing systems, once the base has been laid down. New video or audio may be inserted over a piece of the same size, but a segment can't be added or deleted without re-editing from that point to the end. Edit decision lists have made re-editing easier, but it is still costly. Word processors allow us to manipulate words in a nonlinear way. We cut and paste them so easily that we almost forget that we are rippling everything downstream from where we made the change. Nonlinear video editing on a computer is the same concept as word processing, only it "cuts and pastes" moving video pictures and sound on a timeline instead of text.

Film has always been a nonlinear medium. A piece can be added or deleted. Video tape doesn't easily lend itself to splicing without losing sync and risking damage to the video heads. Now that film style (nonlinear) editing can be economically done on computer based video systems, we will start to see a revolutionary change in the way edit decisions are made. Whenever there is a technological revolution there are always some people who get "burned" because they chose a system that wasn't easily upgradeable, became obsolete too fast, wasn't well refined or wasn't well supported by the manufacturer. It isn't always a good idea to sit by and take a "wait and see" attitude lest you get left in the dust. On the other hand, you don't want to be a guinea pig for some company trying out their new unrefined system. Nonlinear video editing has been around for a few years now, but it is starting to come of age. Many new manufacturers are about to introduce their first system and several existing companies are making dramatic improvements to their existing products or offering new products at previously unheard of low price points. In an upcoming article on "Nonlinear" editing systems, I will elaborate on a variety of systems, many of which were introduced at NAB'93.

Nonlinear editing systems have an additional benefit that most of us have enjoyed for some time now with word processing or desk top publishing. It lets the creative juices flow. When the ability exists to organize ideas or pictures instantly, a better product can be created. If you've ever done desk top publishing on a computer, you know that it doesn't necessarily take less time. The job could be done in significantly less time, but because of the increased ability to create, you tend to push the system to its limit to create a better product.

The definitions of what is "off-line" and what is "on-line" quality for video tape editing depends upon to whom you speak. Nonlinear video editing; however, has been almost exclusively off-line to date. The quality of the pictures has only been good enough for making edit decisions. The EDL (Edit Decision List) is then taken to a conventional linear on-line suite to perform the actual edit. Several companies recently introduced what they call "on-line" quality nonlinear at the NAB convention. With these systems, once you've done your nonlinear edit, you've also finished your on-line. All you have to do is dump it to the tape format of your choice. We are now getting back into the question of what quality level is considered high enough to be called on-line. Some of the new systems that are referred to as "on-line", use skip field recording, where there are 30 frames per second but every other field is skipped. Thus; you do not have 60 different fields per second. This manifests itself in less smooth video and therefore may only be satisfactory as an on-line video for in-house video. Most on-line nonlinear systems use some form of compression algorithm to minimize drive storage and that creates various degrees of artifacts.

I utilized an EMC2 nonlinear IBM based system to off-line my Israeli project. EMC was the first to market a digital nonlinear system (1988) and actually license some other companies to use their patented technology. This system costs between $30,000 - $60,000 Canadian, depending on the configuration. The EMC2 system which I used had 4 different off-line quality level choices, and a new hardware/software upgrade (called PrimeTime), recently made for a fifth and sixth choice with even higher quality. J-Peg C-Cube (CL550B) image compression is used. With any system, the higher the quality the more disk storage that is required. We had only two Maxoptix (Maxtor) Tahiti 1 rewritable magneto-optical drives available to us, so I dropped back to quality level 3 to try and accommodate as much of the 2:45 hours worth of logged material as I could. Each drive could hold approximately 55 minutes of video at quality level 4 or 83 minutes at quality level 3, when recording every other frame. It is desirable to have all of the logged footage instantly accessible from the drives; otherwise, the program would have to be organized in chunks. Because we had viewed all of our logged material, we knew it was fine quality. It was; therefore, not necessary to see it in the highest resolution just to make editing decisions. If the material wasn't logged or the client couldn't relate to the low quality pictures of level 3, you would probably choose a higher resolution and make sure there were enough drives to support all of the material.

Logging the material can take a lot of time, but it significantly reduces the drive storage that is needed and cuts down on the amount of time that is spent in the nonlinear suite. Logging is the process of selecting clips, scenes or pulls with their appropriate in/out times, the reel name and a 38 character note. These logs form the basis of available material for the timeline, which is later "honed" down. Notes come in very handy when doing a word search to find a particular scene, especially when you have over 900 scenes as we did. It is important; however, to determine what each scene will be called. If key words, such as "music", have not been uniformly used for all the scenes that have music, you will not be able to take full advantage of the search function. In the EMC2 program, you can also search for your scene using storyboard type pictures which show the first frame of each scene.

Unlike some systems, the EMC2 does not require you to pre-log your scenes before transferring them into the system. The EMC2 comes with its own logging program which will also work with almost any IBM which has 640K of memory (even an old XT will do). The logging program will also interface with a Videomedia V-lan control and the serial port, which facilitates the entering of in and out points with one key stroke each, instead of eight, when hooked to a player with an RS-422 port and time code reader. I found this very handy and it eliminates typing errors for the time code. Other controllers (protocol adapters) such as AEC, Logic 22 or Telecom can also be used.

EMC also provides a Mac based log program for those using that platform. I most often use a Commodore Amiga 3000, so I purchased the Cross Dos/Cross PC 5.05 software from Consultron and Microsoft MS-DOS 5.0 software. Cross PC software allows an Amiga to emulate an IBM XT without additional hardware and will run most programs. Cross Dos tells an Amiga floppy drive to read or write IBM formatted disks much like the Apple file exchange program on a Macintosh with a Superdrive or Insignia Solution's Access PC, Version 2 (for the Mac). The logging program did work on the Amiga although somewhat slowly. Unfortunately, I could not get the serial port to properly communicate with the V-lan, so I abandoned the idea of logging with the Amiga. Consultron does warn that some timing sensitive serial controls might not work.

I found the EMC log program to be a little basic, but it did get the job done. Third party logging programs are available which can be read into the EMC2 system, as can standard CMX lists. Logging programs usually allow for 3 seconds of slop (extra footage) on either side of a piece of chosen footage (pull or scene). The purpose is to allow you to change your mind during the edit decision process and extend the in or out points. We chose our pulls very exactly with only 1 second of slop to minimize the space needed for drive storage.

When drastically logging your footage down from 43 hours to 2:45 hours plus slop, you will usually wish you had more to choose from. Fortunately, you can always add inserts from non-logged camera masters at the on-line stage as long as you have your base material in order.

The EMC2 system has the ability to work with almost any large hard drive or several optical drives (Sony, Pinnacle & Tahiti). This one was equipped with rewritable magneto-optical drives that use a removable media cartridge with an optical disk inside it that resembles a CD (platter) and looks like a huge floppy on the outside. Each side holds 500 megabytes of information, with one side used for video and the other side for archiving audio. Like most drives, there is only one read/write head so it cannot play the audio from the B side while it is playing video from side A. Instead, it dumps the audio to a huge hard drive in the computer, which allows simultaneous play back of audio and video.

If you have a large enough hard drive that is partitioned into several sections, you can make do with fewer magneto-optical drives by storing the audio from each optical disk in its own partition on the hard drive. If you don't, then you have to wait for 18 minutes at resolution 3 (8 bit 22KHz) to dump the audio from the optical disk to the hard drive each time you want to change disks. Magneto-optical drives are considerably more expensive than hard drives but the removable media optical disks are very inexpensive ($250.) for the amount of storage they provide. I like the idea of removable media so you can switch jobs (clients) by just switching disks, without cleaning off all of your other projects.

Unlike hard drives that use a sealed hard disk, it is possible to contaminate a magneto-optical disk because it has a sliding door just like a floppy. The system I used did not have fully automatic disk management for the magneto-optical drive, so I had to manually keep track of which spots on the disk could be written over, once I had finished with them. This can be a real pain and it also means that I couldn't map out bad sections of the disk and tell the system not to use them. Apparently, EMC has just come out with a utility program that allows disc mapping and diagnostics.

Normally the EMC2 would be installed with a 486/33MHz IBM computer, but the only demo unit available to me had a 286/12MHz computer. It was painfully slow once my timeline started to get big. The EMC2 can be used for film editing with match back SMPTE to edge code or for PAL, SECAM and NTSC video. Switcher wipes, dissolves and some DVE moves can be rendered and then played back in realtime if you feel that you need to see the effect at this stage. I did not bother with many of them as I was only interested in obtaining a fairly clean EDL and then fine tuning it on-line. If the material is logged, the EMC2 is capable of an automatic transfer of scenes to the drive in realtime using a V-lan and RS-422 controlled player. If the reels are properly numbered as per instructions in the manual, all that needs to be done is to change them when it asks you to. If you ploughed ahead without following directions, then the time code could be contaminated. Rather than use my original camera masters for logging and transferring to the EMC2, I made VHS copies with a time code window burned in. This window burn assisted me greatly when I needed to confirm at which piece of material I was looking.

Without the optional kit, the EMC2 will only read time code from the linear audio time code track. Since we recorded all of our time code in the vertical interval (VITC) and kept the linear track free for audio, I used an Evertz Microsystems Ltd. S622N-VCG "VITC to linear time code translator" to make my working window dub copies with linear time code. This unit was very versatile and reliable. When making time coded copies with an outboard VITC reader/translator, you must always remember to hook in the time code reader after the TBC (if you used one), so the linear time code output of the translator is synchronized to the correct frame.

Visual timeline editing made it easy to move a clip (scene or insert) around, once I learned how to do it. Clips can be manipulated from the in or out point, in a source or master dominance mode, with ripple on or off. It can get pretty complex, given all the different ways that you can achieve your desired result. The EMC2 system was far more powerful than I was able to take advantage of on this one project. Most functions could be controlled by the keyboard, a mouse or a dedicated editpad which are all available simultaneously. The fast forward shuttle ability left something to be desired, but, it wasn't needed all that often since you can jump anywhere you want in the timeline by several methods. Unlike conventional tape based editing, there is no recorder with a nonlinear system. Your edit choices on the timeline, play back instantly from the drives. When you're done, you save the timeline as an EDL (Edit Decision List) on a floppy in the format you intend to use on-line. CMX, Grass Valley, Sony, SMPTE and other EDL formats were available. Since your timeline picture plays back on an SVGA monitor, you can use an SVGA to video encoder/scan-line converter such as the Willow, to record the project to tape for customer approval.

Some Canadians may be interested to know that the EMC2 system supports English, French, German, Spanish and Italian languages. Since there is only one video timeline, it was not possible to run two concurrent sources on screen as you would when doing a live A/B roll edit. I found this to be a bit limiting; however, there is an iso function that allows synchronization of five cameras, with one camera playing from the timeline and the corresponding still frame from each of the other four cameras available whenever the timeline is stopped. Because this system runs on an IBM platform, it is open architecture and fully upgradeable. EMC writes the software to address off the shelf hardware.

Despite what you might read in sales literature or hear at a convention, the learning curve for proficiency on any nonlinear system is very time consuming. We are talking about hardware/software packages that are extremely complex and allow you several ways of achieving your goals. Owning a nonlinear system is no more recommended for the casual user than owning an on-line system. If you only have occasional need for nonlinear editing, you would be far better off utilizing a facility that rents time with an operator in the same way you would if you were renting on-line time. One such operator in Toronto is Van La Pointe of Reel Sound and Video Production (416) 588-7468 who gave me plenty of advice when I was learning how to use the EMC2 system. A full time operator has learned the system with all of its idiosyncrasies and can whiz you through a project in a fraction of the time that you could do it yourself. You will come away with a cleaner EDL and a full time operator would likely have enough expensive drives to accommodate all of your material.

It is amazing how many people base their purchase decisions for nonlinear systems primarily on the computer platform that hosts it. There appears to be a strong preference to Mac based systems because of their user friendliness and intuitive interface, but any nonlinear system is only as good as the company that created the proprietary hardware and software. How well that company and its dealers handle customer support and how upgradeable the product is, are factors that are just as important. EMC, in its newest software/hardware upgrade (PrimeTime), have introduced an icon based front end, that eliminates the need to know DOS completely. If you're not a DOS maestro who knows all the obscure DOS commands, you will appreciate this new feature. Also introduced were 5 more choices of audio quality using the Turtle Beach card (including CD quality 44.1KHz 16 bit audio), 2 higher levels of video quality, importation of 16 bit Targa images, audio dissolves and SCSI-II drive control. As nonlinear systems start to become popular, there will be a number of manufacturers leapfrogging each other in capabilities and there will be some former snake oil salesmen now selling nonlinear systems. Let the buyer beware!

In next month's issue, I'll write about our "on-line" experiences with this Israeli project including interformat A/B roll editing from S-VHS to Betacam SP. Also discussed will be an inexpensive computer based edit controller, 24 bit animation, monitors, graphics, two switchers, Magni scopes, an Omicron genlock and the new JVC variable tracking (slow motion) SVHS player.

For more info contact Doug Hembruff  

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