Developer Documentation

QuickTime 4 API Documentation

QuickTime Movie File Format Specification, May 1996

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Graphics Modes

QuickTime files use graphics modes to describe how one video or graphics layer should be combined with the layers beneath it. Graphics modes are also known as transfer modes. Some graphics modes require a color to be specified for certain operations, such as blending to determine the blend level. QuickTime uses the graphics modes defined by QuickDraw. For information on QuickDraw graphics modes, see Inside Macintosh: Imaging.

The most common graphics modes are srcCopy (0x00) and ditherCopy (0x040), which simply indicate that the image should not blend with the image behind it, but overwrite it. QuickTime also defines several new graphics modes.

Table 0-13 lists the new graphics modes supported by QuickTime.

Table 13 QuickTime graphics modes

Graphics mode value

Description

0x0100

Straight alpha

0x0101

Alpha pre-multiplied with white

0x0102

Alpha pre-multiplied with black
© 1997 Apple Computer, Inc.

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