[wdmaudiodev] Re: Need help in Passing a test case from KS-Position test

  • From: Matthew van Eerde <Matthew.van.Eerde@xxxxxxxxxxxxx>
  • To: "wdmaudiodev@xxxxxxxxxxxxx" <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Tue, 29 Apr 2014 16:42:31 +0000

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] On Behalf Of Gaurav Khuntale
Sent: Tuesday, April 29, 2014 8:59 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Need help in Passing a test case from KS-Position test

       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?

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