Calling timeBeginPeriod does indeed have the same effect as calling ExSetTimerResolution. This is actually documented, albeit rather indirectly, at this page: http://support.microsoft.com/default.aspx?scid=kb;en-us;306828 As far as I know this is the only user-mode Windows API function that does so. Dugan Porter - Audio API Dev Lead - Microsoft This posting is provided "as is" with no warranties, and confers no rights -----Original Message----- From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of bart@xxxxxxxxxxxxx Sent: Friday, July 25, 2003 2:59 AM To: Martin Puryear Cc: WDM list; Ron Kuper Subject: [wdmaudiodev] Re: MediaPlayer improves USB DPC timing Hi Martin, > MPlay32 is included in Windows; this ought to be quick'n'easy to try, and it uses just the > basic MCI APIs. > I just tried MPlay32 and it behaves the same as Cubase and Wavelab: It only plays without dropouts whenever the Media Player has been playing before and with the WMP still loaded but stopped. So it looks like the WMP sets a setting that MPlay32 does not.... I'll start digging into the SDK and DDK docs and look for it. > For kernel-mode, please read the documentation on ExSetTimerResolution in the Windows > DDK. > I don't think it can be kernelmode in my driver because it is the same driver showing or not showing the problem depending on a user more state. Or is there a user mode API (in the form of an ioctl) to call ExSetTimerResolution? Sounds quite dangerous to me if there was.... Regards, Bart ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.de/ ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.de/