[wdmaudiodev] Re: Record Buffer Issue
- From: Yura <spirit@xxxxxxxxxx>
- To: "David A. Hoatson" <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Thu, 16 Sep 2004 18:27:49 +0300
Hello ,David
You can hook IOCTL_KS_PROPERTY in the Dispatch routine and look for
the GET request for the KSPROPERTY_CONNECTION_ALLOCATORFRAMING
property of KSPROPSETID_Connection propery set. In this request you
can modify number of buffers and their sizes (after it has been
processed by lower drivers).
I know, this is bad way, but it helped me when I had problems with
sound recording in MsVad.
Thursday, September 16, 2004, 5:30:39 PM, you wrote:
DAH> I have noticed some specific behaviour for recording that is causing major
DAH> grief for my audio driver
DAH> (IMiniportWavePci/IMiniportWavePciStream).
DAH> For playback, the buffers are chopped up into 10ms increments and it seems
DAH> that a maximum of about 3 buffers are sent down to my driver from the WDM
DAH> port class driver. If the sample rate scales up, so does the buffer size
DAH> so each buffer is still 10ms in length. Playback at any sample rate works
DAH> as expected.
DAH> For recording, eight 64-byte buffers are passed in regardless of sample
DAH> rate. At 48kHz stereo, this means each buffer represents ~0.66ms, which is
DAH> just at the limit of what gives acceptable performance from faster
DAH> machines. At 192kHz, the port driver still only gives eight 64-byte
DAH> buffers, so now that same buffer only represents 0.166ms for stereo, or
DAH> only 1 sample period for 16 channel interleaved 32-bit (which my device can
DAH> do)! This means the PC is not able to respond to each interrupt fast
DAH> enough and audio breakup will occur in only 1.3ms (192kHz/Stereo). This
DAH> essentially means that recording through the port class driver is not
DAH> possible at higher sample rates/higher channel counts. I should mention
DAH> that I am using Windows XP SP2.
DAH> So far I have found nothing that allows my driver to control the size or
DAH> number of buffers that are passed in from the upper level driver. Does
DAH> anyone have a solution to this problem? I'm sure there is something very
DAH> basic that I am missing...
DAH> Thank you,
DAH> David
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--
Best regards,
Yura mailto:spirit@xxxxxxxxxx
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