Quicktime File Format (2012-08-14).pdf

Glossaryclassic atom A QuickTime atom that contains noother atoms. A classic atom, however, may containa table. An example of a classic atom is an edit listatom, containing the edit list table. Compare QTatom.clipped movie boundary region The region thatcombines the union of all track movie boundaryregions for a movie, which is the movie’s movieboundary region, with the movie’s movie clippingregion, which defines the portion of the movieboundary region that is to be used. See also movieboundary region and movie clipping region.clipping The process of defining the boundariesof a graphics area.closed caption track The closed caption text for aQuickTime movie, which is typically a directtranscription of a sound track and which is stored ina track with a media handler type of 'clcp'.container atom An atom that contains other atoms,possibly including other container atoms.creator signature In the Macintosh file system, afour-character code that identifies the applicationprogram to which a file belongs.data fork In a legacy two-fork Macintosh file, thesection that corresponds to a DOS/Windows file.data handler A piece of software that is responsiblefor reading and writing a media’s data. The datahandler provides data input and output services tothe media’s media handler. See also media handler.data reference A reference to a media’s data.decoder delay The number of “pre-roll” audiosamples needed to reproduce the source audiosignal in an encoded audio stream for a given timeindex. See also encoder delay.display coordinate system The QuickDrawgraphics world, which can be used to displayQuickTime movies, as opposed to the movie’s timecoordinate system, which defines the basic time unitfor each of the movie’s tracks. Compare timecoordinate system.dithering A technique used to improve picturequality when you are attempting to display an imagethat exists at a higher bit-depth representation ona lower bit-depth device. For example, you mightwant to dither a 24 bits per pixel image for displayon an 8-bit screen.dropframe A synchronizing technique that skipstime codes to keep them current with video frames.duration A time interval. Durations are time valuesthat are interpreted as spans of time, rather than aspoints in time.edit list A data structure that arranges a media intoa time sequence.edit state Information defining the current stateof a movie or track with respect to an edit session.QuickTime uses edit states to support undo facilities.effect description A data structure that specifieswhich component will be used to implement aneffect in a movie, and how the component will beconfigured.effect track A modifier track that applies an effect(such as a wipe or dissolve) to a movie. See modifiertrack.encoder delay The term used to describe the delayincurred during encoding to produce properlyformed, encoded audio packets. See also decoderdelay and “Background – AAC Encoding” (page 421).file fork A section of a Macintosh file. See also datafork, resource fork.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.437