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

Media Data Atom TypesText MediaForeground colorA 48-bit RGB color that specifies the text’s foreground color.Text nameA Pascal string specifying the name of the font to use to display the text.Text Media Information AtomThe text media also requires a text media information atom. This media information atom is stored in a basemedia information atom ('minf') in the base media information header atom ('gmhd') (see “Base MediaInformation Atoms” (page 89)). The type of the text media information atom is 'text'.The timecode media information atom contains the following fields:SizeA 32-bit integer that specifies the number of bytes in this text media information atom.TypeA 32-bit integer that identifies the atom type; this field must be set to 'text'.Matrix structureA matrix structure associated with this text media. This should be the identity matrix. A matrix showshow to map points from one coordinate space into another. See “Matrices” (page 320) for a discussion ofhow display matrices are used in QuickTime and see Figure 2-3 (page 44) for an illustration of a matrixstructure within an atom.Text Sample DataThe format of the text data is a 16-bit length word followed by the actual text. The length word specifies thenumber of bytes of text, not including the length word itself. Following the text, there may be one or moreatoms containing additional information for drawing and searching the text.Table 4-10 (page 196) lists the currently defined text sample extensions.Table 4-10Text sampleextension'styl'Text sample extensionsDescriptionStyle information for the text. Allows you to override the default style in the sampledescription or to define more than one style for a sample. The data is a TextEdit stylescrap.2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.196