With many systems it's even possible to compress or expand the length of audio and video segments. T here are dozens of editing programs available, all of them different in their operation and on-screen configuration, so this discussion must by necessity stick to generalities. Using a mouse, you can drag the frames to whatever sequence you want. Once you are satisfied, you can output the result to a recording medium such as videotape. With some of these simple editors you can apply special effects to the clips and add transition effects between the segments.
M ost editing systems also use one or more timelines to represent the ongoing editing sequence.
With a mouse you can click on and drag the various audio and video segments, transitions, special effects, etc., to the timeline. Once there, they can be rearranged and modified as needed. S ophisticated nonlinear editors have multiple timelines to indicate the simultaneous presence of more than one audio or video source. For example, you could have background music on one timeline, the background sound from your original videotape on another, and the voice of a narrator on a third timeline. Note that in the illustration above there are three audio timelines.