[wdmaudiodev] Audio dropouts with simple filter graph.

  • From: Tom Eckert <teckert@xxxxxxxxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Tue, 19 Mar 2019 13:18:35 -0400

We have an issue discovered by a customer who is using a DirectShow filter graph to provide a monitor stream and we've been able to duplicate the behavior with GraphStudioNext.

After running clean for about 40 minutes we start to hear audio dropouts.  Our debug log shows that the player stream is paused and resumed.  This coincides with increased CPU utilization (but it didn't go over 50%).

I've attached a screenshot of the graph plus the timing log we generated during the test.

At first, I assumed that the thread handling the read from the record side fell behind and the play stream had to be paused briefly to prevent underflow.  But the log shows that prior to the pause the CopyFrom calls are spot on.  Also, the CopyTo's are about 20 ms ahead of the play pointer just as they are when it's playing clean.

Has anyone experienced similar behavior?  Or can you suggest what driver behavior might be causing the graph to pause/resume like this.

Thanks and regards,

Thomas Eckert
AudioScience, Inc

Attachment: DirectShowIssue#467.pdf
Description: Adobe PDF document

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