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Non-Linear (Video) Editing system: in contrast to the older Linear video editing system, which operated by writing video segments to tape, starting at the beginning of the program and working to the end. If a program was to be lengthened or shortened, everything from the cut point until the end would have to be re-edited - or else "dubbed", losing a generation of quality. Needless to say, this was very restrictive.

All modern digital video editing systems are non-linear[citation needed], allowing the (human) editor to insert, delete, trim and move segments at will. Avisynth is a type of NLE (the world's smallest by a factor of 500), as changing clips around, lengthening or trimming them, is very simple and straightforward.

[edit] Example

Suppose we start with the following clips, and we want to assemble a program:

clip_intro = AviSource("intro.avi")
clip_main = AviSource("main.avi")
clip_outro = AviSource("outro.avi")
B = BlankClip(clip_main)

Here is our first edit:

edit_1 = clip_intro
\     ++ B.Trim(0, -15) 
\     ++ clip_main 
\     ++ clip_outro
return edit_1

We find it runs a little too long, but it's easy trim it down a bit here and there:

edit_2 = clip_intro
\         .Trim(0, clip_intro.FrameCount-5)
\     ++ B.Trim(0, -15) 
\     ++ clip_main
\         .Trim(0, 12345)
\     ++ clip_main
\         .Trim(12390, 0)
\         .FadeOut(15) 
\     ++ clip_outro
\         .FadeIn(15)
return edit_2
[edit] More Information

Wikipedia: Non-linear editing system

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