Double-system recording is a form of sound recording used in

motion picture A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere ...

production Production may refer to: Economics and business * Production (economics) * Production, the act of manufacturing goods * Production, in the outline of industrial organization, the act of making products (goods and services) * Production as a stati ...

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 A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere ...

. Recording sound-on-film directly at the time of photography has several technical limitations, and no professional

motion picture camera A movie camera (also known as a film camera and cine-camera) is a type of photographic camera that rapidly takes a sequence of photographs, either on an image sensor or onto film stock, in order to produce a moving image to project onto a movie sc ...

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 An interlock is a feature that makes the state of two mechanisms or functions mutually dependent. It may be used to prevent undesired states in a finite-state machine, and may consist of any electrical, electronic, or mechanical devices or system ...

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 Clapper or Clappers may refer to: Miscellaneous *Clapper, part of a bell *Clapper (musical instrument), consisting of two pieces of wood struck together *Clapper bridge, an ancient form of bridge *Clapper Post, urban postal service of Vienna (XVI ...

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 generally a phonograph lathe. Once magnetic recording became viable, a succession of magnetic sound recorders, culminating in the

Nagra Nagra is a brand of portable audio recorders produced from 1951 in Switzerland. Beginning in 1997 a range of high-end equipment aimed at the audiophile community was introduced, and Nagra expanded the company’s product lines into new markets. ...

, were the standard. As of 2007, most double-system production sound is recorded with

hard disk drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnet ...

-based digital recorders, with a DAT backup. When the apparatus recording sound and image are the same, as in a

video tape recorder A video tape recorder (VTR) is a tape recorder designed to record and playback video and audio material from magnetic tape. The early VTRs were open-reel devices that record on individual reels of 2-inch-wide (5.08 cm) tape. They were use ...

, sound is recorded directly onto the picture medium, and this procedure is called '

single-system recording Single system audio is the system of recording ''sound on film'' or ''SOF''. There are two methods of recording, the older method, optical and the later method, magnetic. SOF was primarily used for news film prior to the advent of portable videotap ...

'. On feature films that are photographed on

high-definition video High-definition video (HD video) is video of higher resolution and quality than standard-definition. While there is no standardized meaning for ''high-definition'', generally any video image with considerably more than 480 vertical scan lines (No ...

, audio is often recorded on the video recorder and also on secondary recorder.

References

soundonsound.com
A Practical Guide To Working With Pictures, Part 3,Tips & Tricks, Published August 2000.
thefreedictionary.com sepmagyoutube.com
Magna Tech 10036-3 Film Sound Follower Recorder Player.
Sondor web site

Post Magazine Arri partners with Sondor, September 11, 2010Magna Tech 10036-3 Film Sound Follower Recorder PlayerFilm into video: a guide to merging the technologies
by
Nagra website

Nagra IIC tape recorder held at the British Library

History of Nagra recorders

Stuart Blake Jones, Richard H. Kallenberger, George D. Cvjetnicanin

{{Filmmaking Film production Film and video technology Film editing

See also

References