Access Copy: Also called distribution or reference copy. An access copy should provide easy access or review of the content of a less accessible preservation or intermediate copy. The access copy is often relatively low resolution and made available online. An access copy should be a widely supported format that is easy to playback.
Acetate Film: Also called “safety film” because it was created as a non-flammable alternative to nitrate film stock. Includes cellulose diacetate, cellulose butyrate, cellulose propionate, and cellulose triacetate. Cellulose triacetate has been standard since the 1950s and is usually referred to as simply “acetate”. All acetate film is susceptible to vinegar syndrome. Acetate base film was replaced by polyester.
Acetate Magnetic Tape Base: Cellulose acetate was used as a tape substrate (base) in many early magnetic tapes from the 1940s until the mid 1960s. Acetate is susceptible to vinegar syndrome. Acetate magnetic tape bases were replaced by polyester.
Analog recording: A recording in which continuous magnetic signals are written to the tape that are representations of the voltage signals coming from the recording of the video camera or microphone. Analog signals stored on tape deteriorate with each copy or generation.
Analog video: A system of recording video images that employs continuously varying waveforms to encode brightness, color and the timing information necessary to reproduce a moving image.
Artifact: An undesirable picture element in a video image, which may naturally occur in the recording process and must be eliminated in order to achieve a high quality image. Most common artifacts are cross-color and cross-luminance. Not to be confused with artifact as a cultural product.
Color Fade: The result of chemical instability in color print stocks that leads to magenta prints. In these cases, the yellow and cyan layers have faded, leaving magenta as the only prominent color.
Composite Video: Composite video combines all video and synchronization information into one signal. It was developed as a practical way of broadcasting video. It also allowed video to be transferred via a single wire, and was later adopted as a way to record video onto tape. Beginning with Betacam, professional videotape formats successively replaced recording composite video and instead recorded video as separate components. The advantage being increased quality. Consumer videotape formats continued using composite because of the great advantage of directly recording analog broadcasts and the low cost of manufacturing machines. Later as digital broadcasting and data recording proliferated, composite video gave way to component. Below is a list of some of the more common composite videotape formats:
- Video 2000
- U-matic 3/4″
- 1/4″ CVC
- 1/2″ EIAJ
- 1″ Type A, B, and C
- 2″ Quadruplex videotape
- 2″ Helical Scan (IVC)
Density: When referring to film, the density is the measure of the blackness of the image. Density is affected by both exposure and processing time.
Deterioration: The degradation of videotape, most typically with the binder, which is responsible for holding the magnetic particles on the tape and facilitating tape transport. If the binder loses integrity – through softening, embrittlement, loss of cohesiveness, or loss of lubrication – the tape may become unplayable.
Diacetate: An early form of acetate film stock, diacetate is easily identifiable because it smells like camphor, or moth balls. Diacetate was used for non-theatrical and amateur films in the 1920s and 1930s. It was replaced by cellulose triacetate and other cellulose acetate film stocks.
Eastman Fade: A form of image deterioration associated with films printed on stock manufactured by Eastman Kodak (though other manufacturers and labs often come into play) in the ‘60’s through the ‘80’s, characterized by color shifts to one dominant tone – usually red, pink, or brown.
Emulsion: The photosensitive coating on film that contains the images and other information.
Film Base: The plastic layer that provides the support needed to carry the images, sound, and any other information. Since the 1890s, motion picture film bases have changed from nitrate to acetate to polyester. Audio and video tape bases have included paper (audio only), acetate, PVC and polyester.
Film Leader: Clear or opaque film material located at the beginning and sometimes the end of a motion picture film. The leader protects the film and will often have identifying information written on it.
Fuji Rot: A form of image deterioration associated with films printed on early stock manufactured by the Fuji company in the ‘60’s through the ‘80’s, characterized by large clusters of red, dot-like discolorations on the image.
Gauge: A characteristic of film that refers to the width, perforations, and other physical features. Gauges range from 7.5mm to 105mm, although 8mm, 16mm and 35mm are most common.
I.B. Technicolor: A now-extinct dye-transfer printing process which used three color-tinted negative sources (yellow, cyan, magenta) blended through imbibition (which I.B. represents) to create theatrical prints with extremely saturated colors that kept consistency for decades. In use until 1974, briefly revived in the late ‘90’s, then discontinued for good in 2002.
Inches per Second: Refers to the length of tape traveling past a read or write head during playback or recording. Inches per second is a valid metric for all magnetic tape and machines (both audio and video), but is normally indicated only for variable speed machines such as open reel audio. Abbreviations include ips, in/s, and in/sec. Higher speeds facilitate a broader range of frequencies able to be recorded on a tape, which generally means more fidelity
Magnetic Media: Media in various formats that use magnetic particles to store information. When particles are read by magnetic audio or video heads, the sound and/or images that have been previously recorded will be reproduced. Some examples include: ¼-inch open reel audio, wire recordings, 1-inch video and VHS tapes. Magnetic media may contain analog or digital information dependent on the format.
Magnetic Stripe: A magnetic soundtrack adhered to the side of motion picture film.
Negative: A film element in which light and color values are reversed. In color film, a negative has colors complementary to real life. Films were usually shot on a negative and then printed to create a positive element. Black and white films appear gray or purplish, and color films have an overall orange hue.
Nitrate Film: The earliest film base. Nitrate film is highly flammable when stored in improper conditions and was replaced by acetate stocks by 1951.
NTSC: Initialism for National Television Standards Committee. In 1941, the U.S. committee developed a standard for encoding analog monochrome (black and white) video and audio television signals. Basically, the standard specifies line count, image refresh frequency, synchronization, modulation schemes, and composite signal encoding. The NTSC standard was augmented in 1953 to enable color television as well as monochrome.
Perforations: The holes in the film that allow for mechanical transport. Also called sprocket holes. The number, arrangement, and placement of perforations are different depending on the film gauge.
PAL: Acronym for Phase Alternating Line. A European standard for encoding analog color and monochrome (black and white) video and audio television signals. The standard, fixed in the early 1960s, took into account the weaknesses related to NTSC’s ability to maintain color fidelity. It improved color stability and increased line resolution, but decreased image refresh frequency. Basically, the standard specifies line count, image refresh frequency, synchronization, modulation schemes, and composite signal encoding.
Photochemical Preservation: Preservation of a film by photographic means. Printing a new copy on new film stock and then developing and fixing the image as done using traditional photographic processes.
Polyester Film: Also referred to by Kodak’s brand name ESTAR, polyester film stocks were introduced in the 1950s and are used today for creating preservation elements. Polyester film stock is durable and is not susceptible to vinegar syndrome.
Polyester Magnetic Tape Base: A chemically stable substrate (base) for audio and video magnetic tape. Polyester bases are durable and not susceptible to vinegar syndrome; sticky shed may still occur, but this will depend on the binder composition. Became the norm for manufacturing by the 1970s.
Positive/Print: Motion picture positives/prints are the equivalent of a still photo print. When shining light through the film the image will appear as it would in real life if projected onto a movie screen. A positive or print is usually made from a negative.
Preservation Copy: A preservation copy is a high quality duplicate of the original record. If the original record deteriorates beyond use the preservation copy should be able to take its place. A preservation copy should last for years or decades – at least long enough to plan for making subsequent copies once these become outdated.
Resolution: The measure of how well audio, video, or film can faithfully portray images or sound. Picture cell (pixel) density and bit depth are the units of measure for individual images. Sampling rate and bit depth are the units of measure for moving images and sound.
Reversal Film: A film stock that has no negative, reversal film uses a chemical process so that the film shot in the camera is processed to a positive image. The most famous example would be Kodak’s Kodachrome (known primarily as a home movie format), although other manufacturers also produced reversal film. Reversal film was produced in black and white and color formats.
SECAM: Acronym for Séquentiel couleur à mémoire, French for Sequential Color with Memory. A European developed standard for encoding analog color and monochrome (black and white) video and audio television signals. The standard, fixed in the mid 1960s, reduced vertical color resolution to more closely align with human visual color acuity. There are other significant technical differences from NTSC and PAL. One of the weaknesses of SECAM later turned out to be its difficulty to be accurately edited/mixed in studios. The standard specifies line count, image refresh frequency, synchronization, modulation schemes, and composite signal encoding.
Splice: A method of joining two pieces of film so they can be projected as one continuous piece. There are three methods: the Tape Splice (usually used for editing), the Cement Splice (used for original material), and the far less common Ultra-Sonic Splice (used for Polyester Base film).
Spoking: Condition of magnetic tape and motion picture film where excessive pressure caused by shrinkage or too much winding tension eventually causes deformation. It is identifiable by the pack of tape or film showing radial lines emanating out from the hub of the spool like spokes.
Sticky Shed Syndrome (SSS): Sticky shed is a problem unique to magnetic tape; it is caused by the chemical breakdown of the magnetic tape binder and/or backing layer of the tape. As the binder/backing absorb moisture from the surroundings, they become sticky and often shed brown residue to equipment. During playback the tape may squeal and bind, which can damage both tapes and equipment. This process is also referred to as binder hydrolysis.
Track Layout: Refers to the arrangement of recorded information on magnetic tapes. Tracks are either linear (running the length of the tape), or segmented either diagonally or perpendicularly across the tape. There are many variations within each technique, and some formats use a combination of techniques.
Vinegar Syndrome (film): A deterioration process that affects acetate film base. Vinegar syndrome is identifiable by the vinegar smell that becomes evident as the acetate base breaks down and acetic acid is off-gassed. Films with vinegar syndrome will deteriorate physically, shrinking and losing flexibility. In final stages, films with vinegar syndrome can become fused and resemble a hockey puck.
Vinegar Syndrome (magnetic media): Characteristic of the breakdown of the acetate tape binding and/or backing layer, resulting in the smell of vinegar (acetic acid). The tape may become brittle and difficult to handle.
Wet-gate printing: Printing process during which motion picture film is briefly immersed in a chemical bath that helps to fill in scratches. A wet gate can be incorporated into a film printer or a telecine. Also known as liquid-gate printing.
**CREDIT FOR TERMS GOES TO: National Archives – Archival Formats: Glossary of Terms Terms Used in the Preservation of Audio, Video and Motion Picture Film and to Marc Heuck for a few terms from the New Beverly Website glossary!