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Linear Video Editing

Linear video editing is the process of assembling segments of video from one or more video sources (usually VTPs or video tape players) to a single video source (usually a VTR or video tape recorder). The process typically involves a computer (called an editor) which controls the various tape machines. The computer saves the video source and time-code information in an EDL (edit decision list) for later archival or in case the job is botched at some point. The EDL can then be used to reconstruct (painstakingly) the edit up to the point where the error occurred.

The problem with linear editing is that each piece of video must be laid down to the recorder in real time and once you start, you cannot go back and make a change without re-editing everything after the change.




Non-Linear Video Editing

Non-linear editing differs from linear editing in several fundamental ways.
  • First, video from the field tapes (or whatever the source is) is recorded to the editing computer's hard drive or RAID array prior to the edit session.
  • Next, rather than laying video to the recorder in sequential shots, the segments are assembled using a video-editing software program like Adobe Premier or Macromedia Director. The segments can be moved around at will in a drag-and-drop fashion.
  • Transitions (such as dissolves or wipes) can be placed between the segments. Also, most of these programs have some sort of CG or character generator feature built in for lower-thirds or titles.
  • The work-in-progress can be viewed at any time during the edit in real time. Once the edit is complete, it is finally laid to video.
  • Non-linear video editing removes the need to lay down video in real time. It also allows the individual doing the editing to make changes at any point without affecting the rest of the edit.
  • As you're probably aware of but not always noticing, videos are usually shot out of order. The movie industry shoots certain scenes first, based on budget and logistics. News crews will film segments in a different order than they present them on the news. If you look carefully at movies like The Wizard of Oz, Dorothy's hair changes length several times throughout the movie. A google search of "continuity errors" will show you a raft of other goofs in TV and film resulting from this out-of-order recording.

    Once the film is recorded, it's taken to be edited. "Linear editing" is generally how videos were edited before computers streamlined the process. Editing a video used to be a very time-consuming process; editors had to edit everything onto a tape sequentially, one shot after another, from the beginning to the end. If you wanted to change a series of shots in the middle of your edit, you had to reedit everything forward. For example, if you wanted to take out a scene or lengthen another scene, you had to re-edit the entire video from the changed point to the end, so there would be no gaps or lost scenes following the changed scene. If you've ever tried to combine multiple videos onto a single VHS tape, you will know what I mean.

    Nonlinear editing, which is what computers are used for, give a much, much greater amount of flexibility. Programs like iMovie, Final Cut Pro, Avid Cinema, Adobe Premiere, Pinnacle Studio, and Windows Movie Maker all allow non-linear editing. A non-linear editor functions like a word processor for video; you can rearrange, insert, remove, and reformat the video without having to manually respace everything.

    The way nonlinear video editors work is that they capture all the video files to a hard disk. Once all of the source video is captured and imported, you can freely assemble the video in any order you want. It can take literally hours out of video editing, and is now used from making professional Music videos to CNN segments to Hollywood films to family vacations.

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