[wdmaudiodev] Re: Direct KS question

  • From: "Mitchell Rundle" <mitchr@xxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Wed, 9 Jun 2004 16:26:45 -0700

How large is each input buffer?  Does the behavior change if you
decrease the buffer size by 20%?

Mitch Rundle
Microsoft Corp. 

-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Andrew Sherbrooke
Sent: Wednesday, June 09, 2004 4:13 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Direct KS question

Hi all,

I have a Direct KS user process which speaks to USBAudio.sys. It uses
rings of buffers for input and output, submitting them via
DeviceIoControl, using IOCTL_KS_WRITE_STREAM and IOCTL_KS_READ_STREAM.
It then waits for one of the associated events to become signaled by
calling WaitForMultipleObjects().

Everything works great until we set it up to use 96 kHz stereo input
(we're not using output at that rate, because of bandwidth limitations,
so it's just waiting on the input buffers). However the
WaitForMultipleObjects() call returns immediately, causing our process
to basically spin in a tight loop, never getting valid data.
Occasionally it will work fine, but most of the time it behaves as
described. Output at 96 kHz works. Both directions together work at 44.1
and 48. It appears that input even works alone at 88.2 (although I
haven't tested this exhaustively), and again, infrequently, it works at
96 kHz. Has anyone seen anything like this? Are there known problems
with USBAudio.sys at these higher rates, perhaps (Windows XP Pro,
current release)? Thanks very much!

Sincerely,

Andrew Sherbrooke

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