Dear All: I am developing an audio driver which is based on Streaming Minidriver framework. When I use the filter within "WDM Streaming Capture Devices" category, the audio stream (44100MHz) is listened well. However, when I use the filter of "Audio Capture Sources" folder, there is a serious delay (1 ~ 2 secs) which is happened. I don't know what's happened in this delay. The filter within "Audio Capture Sources" folder is a virtual filter, right? Why can't the MasterClock be offered from DirectShow manager for this filter? Can you help me to solve this problem? Best Regards, H.P.