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QuickTime Movie File Format Specification, May 1996

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Video Media Information Header Atoms

Video media information header atoms define specific color and graphics mode information.

Figure 0-22 shows the structure of a video media information header atom.

Figure 22 The layout of a media information header atom for video

The video media information header atom contains the following data elements.

Size

A 32-bit integer that specifies the number of bytes in this video media information header atom.

Type

A 32-bit integer that identifies the atom type; this field must be set to ' vmhd ' .

Version

A 1-byte specification of the version of this video media information header atom.

Flags

A 3-byte space for video media information flags. There is one defined flag.

No lean ahead

This is a compatibility flag that allows QuickTime to distinguish between movies created for QuickTime 1.0 and newer movies. You should always set this flag to 1, unless you are creating a movie intended for playback using version 1.0 of QuickTime. This flag's value is 0x0001.

Graphics mode

A 16-bit integer that specifies the transfer mode. The transfer mode specifies which Boolean operation QuickDraw should perform when drawing or transferring an image from one location to another.

Opcolor

Three 16-bit values that specify the red, green, and blue colors for the transfer mode operation indicated in the Graphics mode field.

For comprehensive details on transfer modes and opcolors and their values in QuickDraw, see Inside Macintosh: Imaging .

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