Inside Macintosh: QuickTime Components
The clock component data structure is a private data structure. Programs that use your clock component never change the contents of this data structure directly. Your clock component provides functions that allow programs to use this data structure.
The callback header structure specifies the callback function for an operation. Your application can obtain callback function identifiers by calling its clock component's ClockNewCallBack function (described on ClockNewCallBack ).
The QTCallBackHeader data type defines the callback header structure.
struct QTCallBackHeader {
long callBackFlags; /* flags used by clock
component to communicate
scheduling data about
callback to Movie Toolbox */
long reserved1; /* reserved for use by Apple */
char qtPrivate[40]; /* reserved for use by Apple */
};
enum {
qtcbNeedsRateChanges = 1, /* clock needs to
know about rate
changes */
qtcbNeedsTimeChanges = 2 /* clock needs to
know about time
changes */
qtcbNeedsStartStopChanges
= 4 /* clock needs to
know about time
base changes */
};