Cinelerra

Cinelerra is a sophisticated multimedia editor that runs on Linux. It is capable of:
 * Editing ("cutting") video and sound
 * Adding audio and video transitions, such as cross-fading, between cuts.
 * Adding audio and video effects to selected parts of the timeline.
 * Dubbing and mixing many audio channels.
 * Compositing several "tracks" of video.
 * Use keyframes to control effects and levels over time.
 * Edit and render high resolution video.
 * Use a rendering farm.

Cinelerra is both an editor and a compositor. It allows both cutting and layering/mixing at the same time. This means the timeline is rather packed with features. Some of those features are not visible or obvious; for example, the keyframe. Compositing is more relevant to the professional or the advanced amateur.

Cinelerra is an NLE (Non Linear Editor). In contrast to linear editing where film is actually cut and pasted in a "linear" manner to compose a film, a non-linear editing system is a video or audio editing system that can read media materials in any order, then allowing for one to create a "editing lists" telling the system which segments get played independently of the order of the original material. An important feature of modern NLE's is that the original material is not modified in any way; it can also be called a Non-Destructive Editing system.