I looked at MSVad’s GetPosition implementation and it looks like it’s bursty with a 1 ms granularity. So I don’t understand how it’s passing. Can you post the log? From: wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Gaurav Khuntale Sent: Wednesday, April 30, 2014 12:19 AM To: wdmaudiodev@xxxxxxxxxxxxx Subject: [wdmaudiodev] Re: Need help in Passing a test case from KS-Position test Hi Matthew, Thanks for the reply. Actually i tried the same test with MSVAD sample driver and it is passing it. My driver's GetPosition() implementation is exactly same as MSVAD sample driver but still it is failing in that test case. Like MSVAD sample driver, i am using a unit of milliseconds to calculate byte position in GetPosition() function. Thanks, Gaurav On Tue, Apr 29, 2014 at 10:12 PM, Matthew van Eerde <Matthew.van.Eerde@xxxxxxxxxxxxx<mailto:Matthew.van.Eerde@xxxxxxxxxxxxx>> wrote: A standard deviation of 0.3 milliseconds is consistent with a position counter that has a granularity of 1 millisecond, which is too coarse. Your position counter should have a granularity of 1 sample. From: wdmaudiodev-bounce@xxxxxxxxxxxxx<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx> [mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx<mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx>] On Behalf Of Gaurav Khuntale Sent: Tuesday, April 29, 2014 8:59 AM To: wdmaudiodev@xxxxxxxxxxxxx<mailto:wdmaudiodev@xxxxxxxxxxxxx> Subject: [wdmaudiodev] Need help in Passing a test case from KS-Position test Hello, I am working on a virtual audio driver which is based on wave cyclic port driver. The driver similar to the MSVAD sample driver from the DDK. I am facing an issue with understanding a test from KS position test. Following are the extracts from the test log: Collected 6857 good data points which covers 80828.491 ms Detected 0 glitches in 81 seconds Specified sample rate = 176400.000 bytes/sec, 44100.000 samples/sec Calculated sample rate = 176400.004 bytes/sec, 44100.001 samples/sec Sample rate drifting ratio = 0.000002 % Average position noise magnitude = 0.279960 ms STD of position noise = 0.332027 ms 0.247922% of position noise is larger than 0.8 ms Largest short term (2 seconds) position noise average is 0.000547ms FAIL: STD of position noise is 0.332027ms which is larger than 0.3ms End Case: ID 16.26:1.8 : FAIL : Standard Streaming\Rendering Performance Tests\Position Drift and Jitter for AEC : [Mon Apr 28 15:50:02 2014] The GetPosition() implementation is similar to the one in MSVAD. I am not getting what the test wants to say and what it is expecting. So can anyone please explain it to me? Thanks.