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

Glossarysprite An animated image that is managed byQuickTime. A sprite is defined once and is thenanimated by commands that change its position orappearance.sprite track A movie track populated by moviesprites.streaming Delivery of video or audio data over anetwork in real time, to support applications suchas videophone and video conferencing. See MPEG-4.string atom An atom in VR media that containstext.subtitle track The subtitle text for a QuickTimemovie, which is typically a translation from thelanguage of the sound track into a different languageand which is stored in a track with a media handlertype of 'sbtl'.SWF files Files that contain Flash data. See Flash.sync sample A sample that does not rely onpreceding frames for content. See also key frame.Systeme Electronique Couleur avec Memoire SeeSECAM.temporal compression Image compression thatis performed between frames in a sequence. Thiscompression technique takes advantage ofredundancy between adjacent frames in a sequenceto reduce the amount of data that is required toaccurately represent each frame in the sequence.Sequences that have been temporally compressedtypically contain key frames at regular intervals.text track General-purpose text that displays in aQuickTime movie, which is represented as an atomof type 'text'.thumbnail picture A picture that can be createdfrom an existing image that is stored as a pixel map,a picture, or a picture file. A thumbnail picture isuseful for creating small representative images of asource image and in previews for files that containimage data.time base A set of values that define the time basisfor an entity, such as a QuickTime movie. A time baseconsists of a time coordinate system (that is, a timescale and a duration) along with a rate value. Therate value specifies the speed with which time passesfor the time base.time-based data Data that changes or interactswith the user along a time dimension. QuickTime isdesigned to handle time-based data.timecode media A media of type 'tmcd' that isused to store timecode data.timecode track A movie track that stores externaltiming information, such as SMPTE time codes.time coordinate system A set of values that definesthe context for a time base. A time coordinate systemconsists of a time scale and a duration. Together,these values define the coordinate system in whicha time value or a time base has meaning.time scale The number of time units that pass persecond in a time coordinate system. A timecoordinate system that measures time in sixtiethsof a second, for example, has a time scale of 60.time unit The basic unit of measure for time in atime coordinate system. The value of the time unitfor a time coordinate system is represented by theformula (1/time scale) seconds. A time coordinatesystem that has a time scale of 60 measures time interms of sixtieths of a second.time value A value that specifies a number of timeunits in a time coordinate system. A time value maycontain information about a point in time or abouta duration.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.443