Hello Robert, > The KSAUDIO_POSITIONEX struct contains a TimerFrequency field, I > suspect that you can use that to specify that information to the > audio engine. The problem is that timestamp information seems not to be used by system audio engine itself. The engine simply provides this information to WASAPI clients. But MSDN documentation explicitly mentions QueryPerformanceCounter as the timestamp source so audio application developer could rely on it and compare timestamps to QueryPerformanceCounter results to determine position accuracy. As I understand KSAUDIO_POSITIONEX description, two timestamp values are intended to calculate position accuracy and avoid errors added by code execution delays, context switches etc. But WASAPI methods don't provide both timestamp values; instead, there is only a single timestamp value. In such case, it is impossible to avoid errors caused by code execution delays. So my question is: should each audio driver use KeQueryPerformanceCounter to generate timestamps? Regards, Eugene ****************** 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.com/