Double-system recording
Encyclopedia
Double-system recording is a form of sound recording used in motion picture production
whereby the sound for a scene is recorded on a machine that is separate from the camera or picture-recording apparatus.
Double-system recording is the standard procedure on motion pictures that are originally photographed on film
. Recording sound-on-film directly at the time of photography has several technical limitations, and no professional motion picture camera supports this option, so all production sound is recorded on a separate recorder. This procedure requires that both camera and sound recorder share a very accurate time reference, and that the speed of the camera and sound recorders be carefully governed. Originally this was done with an electro-mechanical interlock between the camera and recorder, necessitating a physical link, a cable, between recorder and camera. As quartz-based timers
came into common use, film cameras and sound recorders adopted these, and these were accurate enough to remove the need for an interlock cable.
Double-system recording requires that sound and picture be manually synchronized at the start of every "take" or camera run. This task was performed by the clapper
slate. A clap sound on the recording is matched to the closed clapper image on the printed film, and thus the two recordings can be realigned into sync.
Before magnetic recording, a double-system sound recorder was either a sound camera or a phonograph lathe. Once magnetic recording became viable, a succession of magnetic sound recorders, culminating in the Nagra
, were the standard. As of 2007, most double-system production sound is recorded with hard disk drive-based digital recorders, with a DAT
backup.
When the apparatus recording sound and image are the same, as in a video tape recorder
, sound is recorded directly onto the picture medium, and this procedure is called 'single-system recording'. On feature films that are photographed on high-definition video
, audio is often recorded on the video recorder and also on secondary recorder.
Filmmaking
Filmmaking is the process of making a film, from an initial story, idea, or commission, through scriptwriting, casting, shooting, directing, editing, and screening the finished product before an audience that may result in a theatrical release or television program...
whereby the sound for a scene is recorded on a machine that is separate from the camera or picture-recording apparatus.
Double-system recording is the standard procedure on motion pictures that are originally photographed on film
Film
A film, also called a movie or motion picture, is a series of still or moving images. It is produced by recording photographic images with cameras, or by creating images using animation techniques or visual effects...
. Recording sound-on-film directly at the time of photography has several technical limitations, and no professional motion picture camera supports this option, so all production sound is recorded on a separate recorder. This procedure requires that both camera and sound recorder share a very accurate time reference, and that the speed of the camera and sound recorders be carefully governed. Originally this was done with an electro-mechanical interlock between the camera and recorder, necessitating a physical link, a cable, between recorder and camera. As quartz-based timers
Quartz clock
A quartz clock is a clock that uses an electronic oscillator that is regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with very precise frequency, so that quartz clocks are at least an order of magnitude more accurate than good mechanical clocks...
came into common use, film cameras and sound recorders adopted these, and these were accurate enough to remove the need for an interlock cable.
Double-system recording requires that sound and picture be manually synchronized at the start of every "take" or camera run. This task was performed by the clapper
Clapperboard
A clapperboard is a device used in filmmaking and video production to assist in the synchronizing of picture and sound, and to designate and mark particular scenes and takes recorded during a production...
slate. A clap sound on the recording is matched to the closed clapper image on the printed film, and thus the two recordings can be realigned into sync.
Before magnetic recording, a double-system sound recorder was either a sound camera or a phonograph lathe. Once magnetic recording became viable, a succession of magnetic sound recorders, culminating in the Nagra
Nagra
Nagra is the trademark referring to any of the series of mostly battery-operated portable professional audio recorders produced by Kudelski SA, based in Cheseaux-sur-Lausanne, Switzerland....
, were the standard. As of 2007, most double-system production sound is recorded with hard disk drive-based digital recorders, with a DAT
Digital Audio Tape
Digital Audio Tape is a signal recording and playback medium developed by Sony and introduced in 1987. In appearance it is similar to a compact audio cassette, using 4 mm magnetic tape enclosed in a protective shell, but is roughly half the size at 73 mm × 54 mm × 10.5 mm. As...
backup.
When the apparatus recording sound and image are the same, as in a video tape recorder
Video tape recorder
A video tape recorder is a tape recorder that can record video material, usually on a magnetic tape. VTRs originated as individual tape reels, serving as a replacement for motion picture film stock and making recording for television applications cheaper and quicker. An improved form included the...
, sound is recorded directly onto the picture medium, and this procedure is called 'single-system recording'. On feature films that are photographed on high-definition video
High-definition video
High-definition video or HD video refers to any video system of higher resolution than standard-definition video, and most commonly involves display resolutions of 1,280×720 pixels or 1,920×1,080 pixels...
, audio is often recorded on the video recorder and also on secondary recorder.