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Fundamentals of AV Preservation


Active management: The performance of consistent and ongoing digital preservation activities (e.g., fixity and validation) to ensure a digital file’s continued access for as long as necessary. 

Artifact: Anomalies during visual or aural representations of recordings.

Audit trail: The information associated with a digital file that tracks the transactional history of it from the point of capture or ingest to know whether it has been managed without change to the bits that make it up and according to relevant policies and standards. 

Authenticity: The quality of being genuine and free from tampering and is typically inferred from internal and external evidence, including its physical characteristics, structure, content, and context.1 Trustworthiness. 

Back coat: Layer added to some magnetic tape to help support the magnetic recording layer. The back coat reduces tape friction, dissipates static charge, and reduces tape distortion.

Binder system: System through which magnetic particles are held by a binder to a substrate layer.

Bit rot: The corruption, loss, or decay of bits, the building blocks of digital files. 

Carrier type: Refers to the physical carrier of the av material. Examples of carrier type include reels and cassettes.

Checksums: Alphanumeric strings that reflect the uniqueness of every digital file.

Curation: The activities that are performed on a digital file throughout its lifecycle, including selection and appraisal, description, ongoing care and management, long-term access, and/or deaccessioning/disposal. 

Degradation: The process in which the quality or integrity of an object is destroyed over time.

Delamination: In disc media, the process that causes layers to separate from the support base.

Digital preservation: the active management of digital content over time to ensure ongoing access.”2 It is an integral part of curation (see definition above). 

Digitization:  The representation of an object, image, sound, moving image, or document by generating a series of numbers that describe a discrete set of its points. 

File attendance: Ensuring that there are no missing or unexpectedly present files in a given location.

Fixity: File fixity refers to the property of a digital file being fixed, or unchanged. Fixity checking is the process of verifying that a digital object has not been altered or corrupted.3 

Governance: In the informational sense, governance is the set of structures, policies, procedures, processes, and controls implemented to manage information at an enterprise level, supporting an organization's immediate and future regulatory, legal, risk, environmental and operational requirements.4 

Ingest: The process by which a digital files and their associated metadata (called a Submission Information Package, or SIP) is deposited or submitted into a digital repository. 

Latency: In computer networking, latency is the time interval between the request for information, such as a digital file, and the retrieval or display of that file to the user by the system. 

Machine transport: Playback equipment.

Mandrel: A cylindrical rod placed through a cylinder and used to rotate it for playback.

Media type: AV materials are classified as audio, video, or film during the cataloging and inventory processes.

Metal evaporated tape process: Process in which magnetic particles are vaporized from a solid and deposited onto a substrate layer.

Migration: Converting from one format to another format considered to be of greater stability.

Obsolescence: The state of being which occurs when an object or practice is no longer wanted or used. Usually occurs when a new technology supersedes the old.

Preservation planning: a process by which the general and specific needs for the care of collections are determined, priorities are established, and resources for implementation are identified.

Refreshing: Copying information content from one storage media to the same storage media.5

Reproduction method: Method in which a recorded signal is played back from a physical media object.

Risk management:  The systematic control of losses or damages, including the analysis of threats, implementation of measures to minimize such risks, and implementing recovery programs.6 

RPM: Rotations per minute. Used to indicated recording speed for discs and cylinders. 

Sidecar file:  A file that is stored next to the AV file in the same directory. 

Signal path: The route that an audio signal travels from source to output. This may be within a single device (CD to speaker within a stereo system) or within a workflow (original audio recording to reformatted digital file). 

Slipping: Tape pack problem in which either single strands or groups or strands are misaligned and migrate to rest against the edge of the flange. May cause edge damage to the tape or film.

Splice: When two ends of a tape or film are joined together using specially formulated splicing tape.

Sticky shed syndrome: A condition resulting from the deterioration of the binder in magnetic tape that results in gummy residues on tape heads during playback.7 

Storage architecture: The computing and network infrastructure required to store digital files. 

Storage capacity: The amount of data a storage device can hold, often measured in gigabytes (GB), terabytes (TB), and petabytes (PB). 

Storage media: Devices on which data is stored. These include computer hard disks, optical disk drives, USB drives and other external hard drives, DVDs, and magnetic data storage tapes. 

Stylus: A hard point following a groove in a phonograph record and transmitting the recorded sound for reproduction.

Substrate: The backing film needed to support the magnetic recording layer of a magnetic tape.

Tails out: A method for winding tape onto a reel where the end of the tape is on the outside.