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

Media Data Atom TypesSprite Track PropertiesRefer to the section “Sprite Track Media Format” (page 211) for information on how override samples areindicated in the file, using kSpriteTrackPropertySampleFormat and the default behavior of thekKeyFrameAndSingleOverride format.Sprite Track PropertiesNote Sprite media is deprecated in the QuickTime file format. The information that follows is intendedto document existing content containing sprite media and should not be used for new development.In addition to defining properties for individual sprites, you can also define properties that apply to an entiresprite track. These properties may override default behavior or provide hints to the sprite media handler. Thefollowing sprite track properties are supported:kSpriteTrackPropertyBackgroundColorSpecifies a background color for the sprite track. The background color is used for any area that is notcovered by regular sprites or background sprites. If you do not specify a background color, the spritetrack uses black as the default background color.kSpriteTrackPropertyOffscreenBitDepthSpecifies a preferred bit depth for the sprite track’s offscreen buffer. The allowable values are 8 and 16.To save memory, you should set the value of this property to the minimum depth needed. If you do notspecify a bit depth, the sprite track allocates an offscreen buffer with the depth of the deepest intersectingmonitor.kSpriteTrackPropertySampleFormatSpecifies the sample format for the sprite track. If you do not specify a sample format, the sprite trackuses the default format, kKeyFrameAndSingleOverride.To specify sprite track properties, you create a single QT atom container and add a leaf atom for each propertyyou want to specify. To add the properties to a sprite track, you call the media handler functionSetMediaPropertyAtom. To retrieve a sprite track’s properties, you call the media handler functionGetMediaPropertyAtom.The sprite track properties and their corresponding data types are listed in Table 4-14 (page 210).Table 4-14Sprite track propertiesAtom typekSpriteTrackPropertyBackgroundColorAtom ID1Leaf data typeRGBColor2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.210