Before assembling the footage, the editor collects all audio and video materials required for the movie. An editor's preferred work flow and editing techniques mainly depend on the type of camera used during filming, the editing program and the output form required for the final copy of the movie. The footage can either be shot with a film or a digital video camera. A film camera uses celluloid that requires film processing and digitizing prior to editing. A digital video camera uses a tape or file-based digital storage device that can be readily transferred into the computer for editing. Aside from the video footage, the editor also needs the various special effects, as well as sound and music elements to be used in the movie.
The editor assembles and syncs the video and sound materials according to how they should appear in the final movie. This assembly follows the script and storyboard approved by the director and the producer of the project. The editor must be knowledgeable in film language to determine which shots and takes should be used to tell the story in audio-visual form. Knowing the right shot distance, angle and movement to use for a particular scene is a vital part of the editor's job. Choosing the best shots go beyond the technical requirements of telling the story. The emotional content of each shot is also a primary consideration when editing.
Although many shots in a movie are directly spliced together, there are times that video transitions are used to denote the passage of time or show flashbacks and other possible situations that would require transition effects, such as dissolves and fades. A "cross dissolve" is a popular transition effect in between two separate shots. This requires combining two shots, with the first shot slowly disappearing while the second shot slowly appears. A "fade in" is a shot that slowly appears from a black screen, and a "fade out" has the shot slowly disappearing into a black screen. These types of transition effects can also be applied along with music and sound effects.
The editor must match a movie's shots in a way that the familiar relationship between various scenes looks accurate, both physically and thematically. For instance, a scene of a person about to drink from a cup can be divided into two shots. How she holds the cup, from the wide shot where she is about to drink, should correspond to the close-up shot as she drinks to when she finishes. The editor should be careful, when matching shots, as there is the possibility that the way the actor holds the cup on the first shot may be quite different as how she holds it on the second shot. If the movie has a voice over narrative, that voice should have continuity in intonation and voice quality -- regardless of the time the voice over was recorded. The emotional aspect of how a scene is presented is also important for the film's thematic continuity.