AB roll -

      Synchronized playback of two recorded video images so that one can perform effects, such as dissolves, wipes, or inserts, using both images simultaneously.
    ACPA -
      Audio capture and playback adapter.
    active matrix -
      A technology that gives every pel (dot) on the screen its own transistor to control it more accurately. (This allows for better contrast and less motion smearing.)
    adaptive differential pulse code modulation -
      A bit-rate reduction technique where the difference in pulse code modulation samples are not compressed before being stored.
    ADC -
      Analog-to-digital converter.
    ADPCM -
      Adaptive differential pulse code modulation.
    aliasing -
      The phenomenon of generating a false (alias) frequency, along with the correct one, as an artifact of sampling a signal at discrete points. In audio, this produces a "buzz." In imagery, this produces a jagged edge, or stair-step effect. See also moire.
    all points addressable (APA) -
      In computer graphics, pertaining to the ability to address and display or not display each picture element on a display surface.
    AM -
      Animation metafile.
    ambience -
      In audio, the reverberation pattern of a particular concert hall, or listening space.
    ambient noise -
      In acoustics, the noise associated with a particular environment, usually a composite of sounds from many distant or nearby sources.
    American National Standards Institute (ANSI) -
      An organization consisting of producers, consumers, and general interest groups, that establishes the procedures by which accredited organizations create and maintain voluntary industry standards in the United States.
    AMF -
      Animation metafile format.
    amp -
      See amplifier.
    amplifier -
      (1) A device that increases the strength of input signals (either voltage or current). (2) Also referred to as an amp.
    amp-mixer -
      (1) A combination amplifier and mixer that is used to control the characteristics of an audio signal from one or more audio sources. (2) Also referred to as an amplifier-mixer.
    analog -
      Pertaining to data consisting of continuously variable physical quantities. Contrast with digital.
    analog audio -
      Audio in which all information representing sounds is stored or transmitted in a continuous-scale electrical signal, such as line level audio in stereo components. See also digital audio.
    analog-to-digital converter (ADC) -
      A functional unit that converts data from an analog representation to a digital representation. (I) (A)
    analog video -
      Video in which all the information representing images is in a continuous-scale electrical signal for both amplitude and time. See also digital video.
    analog video overlay -
      See overlay.
    anchor -
      An area of a display screen that is activated to accept user input. Synonymous with hot spot, touch area, and trigger.
    animate -
      Make or design in such a way as to create apparently spontaneous, lifelike movement.
    animated -
      Having the appearance of something alive.
    animated screen capture -
      Recording a computing session for replay on a similar computer with voice annotation. (An example is sending a spreadsheet with an accompanying screen recording as an explanation and overview.)
    animatic -
      A limited animation consisting of artwork shot on film or videotape and edited to serve as an on-screen storyboard.
    animation metafile -
      A compound file format, the elements of which are the frames of animation themselves. These frames are stored sequentially so that they can be played back in time by streaming to the video agent.
    animation metafile format (AMF) -
      The file format used to store animated frame sequences.
    annotation -
      The linking of an object with another, where the second contains some information related to the first. For example, an audio annotation of a spreadsheet cell might contain verbal explanation about the contents of the cell.
    ANSI -
      American National Standards Institute.
    anthropomorphic software agent -
      The concept of a simulated agent, seemingly living inside the computer, that talks to and listens to the user, and then acts for the user on command.
    antialiasing -
      (1) In imagery, using several intensities of colors (a ramp) between the color of the line and the background color to create the effect of smoother curves and fewer jagged edges on curves and diagonals. (2) In imagery or audio, removing aliases by eliminating frequencies above half the sample frequencies.
    AOCA -
      Audio Object Content Architecture.
    APA -
      All points addressable.
    APA graphics -
      All Points Addressable graphics. See bitmap graphics.
    API -
      Application programming interface.
    application programming interface (API) -
      A functional interface supplied by the operating system or an IBM separately orderable licensed program that allows an application program written in a high-level language to use specific data or functions of the operating system or the licensed program.
    application-supplied video window -
      (1) An application can specify to MMPM/2 that it wants video played in a specific window (controlled by the application) instead of the default window (controlled by MMPM/2). The application supplied video window can be used to implement advanced features not supported by the default video window. (2) Also referred to as an alternate video window.
    artifact -
      A product resulting from human activity; in computer activity, a (usually unwanted) by-product of a process.
    aspect ratio -
      (1) On a display screen, the ratio of the maximum length of a display line to the maximum length of a display column. (2) The ratio of height to width. (This term applies to areas or individual pels.) Refer to enhanced graphics adapter and video graphics adapter.
    asymmetric video compression -
      In multimedia applications, the use of a powerful computer to compress a video for mastering so that a less powerful (less expensive) system is needed to decompress it. Contrast with symmetric video compression.
    audible cue -
      A sound generated by the computer to draw a user's attention to, or provide feedback about, an event or state of the computer. Audible cues enhance and reinforce visible cues.
    audio -
      Pertaining to the portion of recorded information that can be heard.
    audio attribute control -
      Provides access to and operation of the standard audio attributes: mute, volume, balance, treble, and bass. All device communication and user interface support is handled by the control.
    audio attributes -
      Refers to the standard audio attributes: mute, volume, balance, treble and bass.
    audio clip -
      A section of recorded audio material.
    Audio Object Content Architecture -
      A data format for multimedia products.
    audio processing -
      Manipulating digital audio to, for example, edit or create special effects.
    audio segment -
      A contiguous set of recorded data from an audio track. An audio segment might or might not be associated with a video segment.
    audio track -
      (1) The audio (sound) portion of the program. (2) The physical location where the audio is placed beside the image. (A system with two audio tracks can have either stereo sound or two independent audio tracks.) (3) Synonym for sound track.
    audiovisual -
      A generic term referring to experiences, equipment, and materials used for communication that make use of both hearing and sight.
    Audio Visual Connection* (AVC) -
      An authoring system used on an IBM PS/2* to develop and display audiovisual productions.
    audiovisual computer program -
      A computer program that makes use of both hearing and sight.
    authoring -
      A structured approach to combining all media elements within an interactive production, assisted by computer software designed for this purpose.
    authoring system -
      A set of tools used to create an interactive multimedia application without implementing formal programming.
    AVI file format -
      The Audio/Video Interleaved (AVI) file format is the standard file format used to support software motion video. AVI files can contain multiple streams (tracks) of data (for example, a video and an audio stream). The streams are interleaved to improve access times during playback. The present implementation is limited to a single video stream and a single, optional, audio stream.


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