Several video editing systems have been introduced this year which are designed to permit "film style" editing of either videotape or transfers of film original. Editing in any medium is a matter of selecting pieces, assembling sequences, adjusting transitions and rearranging pieces of picture and sound, but the techniques used are often dependent on the tools available. Film editing techniques or procedures have evolved with the development of the Moviola, magnetic sound tracks, tape splicers and flatbed editing tables. There is, in fact, no single standard procedure for film editing. The editor's methods may vary according to whether he or she is cutting 16mm or 35mm on a Moviola or a flatbed with or without an assistant editor. They may also vary according to the editor's creative approach and the subject matter of the material being edited.
Videotape editing has its roots in the procedures of live multicamera broadcasting. A great deal of videotape editing technique is still based on concepts derived from the process of switching between cameras during a live broadcast. The development of videotape recording, however, opened the door for the evolution of a different style of editing in videotape. In the early days videotapes were physically cut and spliced in a way similar to film except that the positioning of the splice was much more difficult and critical. Since there are no sprocket holes or visible frame lines, it was necessary to sprinkle iron filings on the tape and examine them under a magnifier to detect the magnetized portions corresponding to the frame lines. Although this form of editing was cumbersome, it did permit greater flexibility in the taping of television programs and as late as 1970 Laugh In was being edited in this way. The real breakthrough in video editing techniques came with the development of time code, which made possible frame accurate editing by re-recording. (For an overview of time code based video editing procedures see Gary H. Anderson's "Understanding Video Edit Systems" in the January 1984 issue of American Cinematographer or in Electronic Production Techniques.)
Editing via re-recording, while it has many advantages, is limited by the fact that it is essentially a "linear" process. Once a series of cuts has been recorded as an edited sequence, there is no way to alter the total length of the sequence except by re-recording all of the cuts coming after the change that has been made. This has been a great source of frustration for film editors who begin editing tape. If the editor builds up a ten minute sequence and then decides to alter a cut by even one frame, he cannot just roll down to the cut, pull a frame or two out and then splice it back together. As a result many film editors have felt that video editing was an efficient means for getting a fast first cut but too cumbersome for the kind of re-cutting and polishing which is customary in most film editing.
This problem has been addressed in several ways. The most obvious compromise is to re-record the entire sequence from the first edited version using whatever other material is required to make changes as you go through the reel. The time required for re-recording can be used for viewing and evaluating the first cut, and the time required to make changes is minimal. While this approach is viable in many situations, it does have two limitations. First of all it involves a loss of image quality which may not be objectionable in a second or third generation recording, but which can become severe after several recuts since most "offline" video editing of this sort is done with ¾'' or conventional ½'' cassettes. One inch master tapes can go through ten generations without an objectionable amount of image degradation, but ¾'' and ½'' cassettes use a different method for recording the signal and cannot adequately survive several generations of re-recording. To go back to the original material at any stage in …