Post production turns individual scenes, called raw footage, into a finished motion picture. Editors splice all of the usable footage together into a coherent storyline according to the script. Composers add background music. Special effects teams add computer-generated images and effects. All of this work can only be performed during post production.
Post production may also involve fixing mistakes not corrected during principal shooting. Quite often an actor’s microphone will not pick up crucial bits of dialogue or another microphone may pick up extraneous noises. During post production, an actor may have to return to a soundbooth in order to re-record lost dialogue or improve the original delivery. This is called looping. Another function of post production is to add incidental sound effects not captured during the original scenes. A specialist called a foley artist will record such sounds as an actor’s footsteps, a creaking door or gunshots.
Many directors and producers rely heavily on the ability of post production teams to create a marketable film. Since principal shooting can be a hectic time for both actors and directors, some footage may prove to be unusable during the post production editing process. A film’s original ending may also be unpopular with test audiences. This could lead to reshoots with the principal actors before a final film is produced. Other responsibilities during post production may include publicity tours, promotional posters, contracts with distributors and the creation of auxiliary formats such as DVDs and soundtrack albums.