Automated dialogue replacement / post-sync
Automated dialogue replacement or Additional dialogue recording (ADR) is a film sound technique involving the re-recording of dialogue after photography, also known as "looping" or a looping session. In the UK it is called post-synchronisation or post-sync.
In conventional film production, a production sound mixer records dialogue during photography, but several uncontrollable issues, such as traffic or animal noise, during principal photography can cause the production sound to be unusable. This is also true for computer-generated imagery, since some of the "actors" were not actually present at the set. In addition, ADR is also used to change the lines which the actor originally said while being filmed.
When the film is in post-production, a Supervising Sound Editor or ADR Supervisor reviews all of the dialogue in the film and rules which actor lines will have to be replaced using the ADR technique.
ADR is recorded during an ADR session. An actor, usually the original actor on set, is called to a sound studio equipped with video playback equipment and sound playback and recording equipment. The actor wears headphones and is shown the line of the film that must be replaced, and often he or she will be played the production sound recording. The film is then projected several times, and the actor attempts to re-perform the line while watching the image on the screen, while an ADR Recordist records the performances. Several takes are made, and based on the quality of the performance and sync, one is selected and edited by an ADR Editor for use in the film.
Sometimes, a different actor is used from the actual actor on set. One famous example is the Star Wars character Darth Vader, portrayed by David Prowse and later Hayden Christensen. In postproduction, James Earl Jones always dubbed the character's voice. Many fans therefore think of Jones as "the man who played Darth Vader" rather than the actors who wore the suit on set.
There are variations of the ADR process. ADR does not have to be recorded in a studio, but can be recorded on location, with mobile equipment; this process was pioneered by Matthew Wood of Skywalker Sound for Star Wars Episode I: The Phantom Menace. ADR can also be recorded without showing the actor the image they must match, but only by having him listen to the performance. This process was used for years at Universal Studios.
An alternative method, called "rythmo band” (or "lip-sync band") was historically used in Canada and France. This band provides a more precise guide for the actors, directors and technicians and can be used to complement the traditional headphone method. The band is actually a clear 35 mm film leader on which is written, in India ink, the dialogue and numerous indications for the actor (laughs, cries, length of syllables, mouth sounds, mouth openings and closings, etc.). The lip-sync band is projected in studio and scrolls in perfect synchronization with the picture. Thanks to the high efficiency of the lip-sync band, the number of retakes are reduced, resulting in a substantial savings in recording time (as much as 50% compared to headphones-only recording).
Historically, the preparation of the lip-sync band is a long, tedious and complex process involving a series of specialists in an old fashioned manual production line. Until recently, such constraints have prevented this technique from being adopted internationally, particularly in the United States.
Advanced software technology has been able to digitally reproduce the rythmo-band output in a fraction of the time. This technology is being adapted in all markets and is proven to reduce the amount of studio time and number of takes required for actors to achieve accurate synchronization.
Using the traditional ADR technique (headphones and video) actors can average 10-12 lines per hour. Using the newer digital rythmo-band technologies, actors can output from 35-50 lines per hour, and much more with experience. Studio output with multiple actors can therefore reach two to four hundred lines per hour. dubStudio has pioneered the digital rythmo-band technology and has been used by several large dubbing studios.
ADR can usually be used to redub singing. This technique was used by, among many others, Billy Boyd and Viggo Mortensen in The Lord of the Rings.[citation needed]
Adding or replacing non-vocal sounds, such as sound effects, is the task of a foley artist.
