I'm trying to modify MSVAD to make a specialized driver. I'm having a bit of a problem with the timing of CopyTo. Inside CopyTo if I count the data delivered it seems a bit slow. If I do something like: CMiniportWaveCyclicStreamMSVAD::CopyTo( IN PVOID Destination, IN PVOID Source, IN ULONG ByteCount ) { g_Total += ByteCount; } and track g_Total I find that the data is being delivered at about 40,000 samples per second, but the format suggests it should get there at 44100. If I allow the data to write to a file as in the sample, the file sounds fine. Is there anything that will slow CopyTo down? Is the data being compressed somehow? Thanks, Jonah