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

Media Data Atom TypesTween MediaTween typeMatrixRGB color: three 16-bit integersGraphics mode with RGB colorValue789Tween dataTwo matrices.Two RGB colors.Two graphics modes with RGB color. Only the RGB coloris interpolated. The graphics modes must be the same.Each tween type is distinguished from other types by these characteristics:●●●●Input values or structures of a particular typeA particular number of input values or structures (most often one or two)Output values or structures of a particular typeA particular algorithm used to derive the output valuesTween operations for each tween type are performed by a tween component that is specific to that type or,for a number of tween types that are native to QuickTime, by QuickTime itself. Movies and applications thatuse tweening do not need to specify the tween component to use; QuickTime identifies a tween type by itstween type identifier and automatically routes its data to the correct tween component or to QuickTime.When a movie contains a tween track, the tween media handler invokes the necessary component (or built-inQuickTime code) for tween operations and delivers the results to another media handler. The receiving mediahandler can then use the values it receives to modify its playback. For example, the data in a tween track canbe used to alter the volume of a sound track.Tweening can also be used outside of movies by applications or other software that can use the values itgenerates.Tween Type CategoriesEach of the tween types supported by QuickTime belongs to one of these categories:●●●Numeric tween types, which have pairs of numeric values, such as long integers, as input. For these types,linear interpolation is used to generate output values.QuickDraw tween types, most of which have pairs of QuickDraw structures, such as points or rectangles,as input. For these types, one or more structure elements are interpolated, such as the h and v values forpoints, and each element that is interpolated is interpolated separately from others.3D tween types, which have a QuickDraw 3D structure such as TQ3Matrix4x4 orTQ3RotateAboutAxisTransformData as input. For these types, a specific 3D transformation is performedon the data to generate output.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.237