timeBeginPeriod function (timeapi.h)
The timeBeginPeriod function requests a minimum resolution for periodic timers.
Syntax
MMRESULT timeBeginPeriod(
UINT uPeriod
);
Parameters
uPeriod
Minimum timer resolution, in milliseconds, for the application or device driver. A lower value specifies a higher (more accurate) resolution.
Return value
Returns TIMERR_NOERROR if successful or TIMERR_NOCANDO if the resolution specified in uPeriod is out of range.
Remarks
Call this function immediately before using timer services, and call the timeEndPeriod function immediately after you are finished using the timer services.
You must match each call to timeBeginPeriod with a call to timeEndPeriod, specifying the same minimum resolution in both calls. An application can make multiple timeBeginPeriod calls as long as each call is matched with a call to timeEndPeriod.
Prior to Windows 10, version 2004, this function affects a global Windows setting. For all processes Windows uses the lowest value (that is, highest resolution) requested by any process. Starting with Windows 10, version 2004, this function no longer affects global timer resolution. For processes which call this function, Windows uses the lowest value (that is, highest resolution) requested by any process. For processes which have not called this function, Windows does not guarantee a higher resolution than the default system resolution.
Starting with Windows 11, if a window-owning process becomes fully occluded, minimized, or otherwise invisible or inaudible to the end user, Windows does not guarantee a higher resolution than the default system resolution. See SetProcessInformation for more information on this behavior.
Setting a higher resolution can improve the accuracy of time-out intervals in wait functions. However, it can also reduce overall system performance, because the thread scheduler switches tasks more often. High resolutions can also prevent the CPU power management system from entering power-saving modes. Setting a higher resolution does not improve the accuracy of the high-resolution performance counter.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | timeapi.h (include Windows.h) |
| Library | Winmm.lib |
| DLL | Winmm.dll |