[wdmaudiodev] Re: Record Buffer Issue
- From: "Jerry Evans" <jerry@xxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Thu, 16 Sep 2004 19:36:40 +0100
Very nice :-)). Thanks.
----- Original Message -----
From: "David A. Hoatson" <dhoatson@xxxxxxx>
To: <wdmaudiodev@xxxxxxxxxxxxx>
Sent: Thursday, September 16, 2004 4:19 PM
Subject: [wdmaudiodev] Re: Record Buffer Issue
> 192kHz PCI audio card with a 16-channel scatter-gather engine. See
> http://www.lynxstudio.com/aes16.html. I support up to 8 cards per system
> for a total of 128 input channels and 128 output channels. US$695/each.
> You can get a demo in London at HHB ;-).
>
> Thank you,
>
> David
>
> ----- Original Message -----
> From: "Jerry Evans" <jerry@xxxxxxxxxx>
> To: <wdmaudiodev@xxxxxxxxxxxxx>
> Sent: Thursday, September 16, 2004 8:07 AM
> Subject: [wdmaudiodev] Re: Record Buffer Issue
>
>
> > Hi David
> >
> > Sorry, this is peripheral to your question: can you tell me what audio
> > hardware you are using here ?
> >
> > Thx
> >
> > Jerry
> > ----- Original Message -----
> > From: "David A. Hoatson" <dhoatson@xxxxxxx>
> > To: <wdmaudiodev@xxxxxxxxxxxxx>
> > Sent: Thursday, September 16, 2004 3:30 PM
> > Subject: [wdmaudiodev] Record Buffer Issue
> >
> >
> >> Hello,
> >>
> >> I have noticed some specific behaviour for recording that is causing
> >> major
> >> grief for my audio driver (IMiniportWavePci/IMiniportWavePciStream).
> >>
> >> For playback, the buffers are chopped up into 10ms increments and it
> >> seems
> >> that a maximum of about 3 buffers are sent down to my driver from the
> >> WDM
> >> port class driver. If the sample rate scales up, so does the buffer
> >> size
> >> so each buffer is still 10ms in length. Playback at any sample rate
> >> works
> >> as expected.
> >>
> >> For recording, eight 64-byte buffers are passed in regardless of sample
> >> rate. At 48kHz stereo, this means each buffer represents ~0.66ms,
which
> > is
> >> just at the limit of what gives acceptable performance from faster
> >> machines. At 192kHz, the port driver still only gives eight 64-byte
> >> buffers, so now that same buffer only represents 0.166ms for stereo, or
> >> only 1 sample period for 16 channel interleaved 32-bit (which my device
> > can
> >> do)! This means the PC is not able to respond to each interrupt fast
> >> enough and audio breakup will occur in only 1.3ms (192kHz/Stereo).
This
> >> essentially means that recording through the port class driver is not
> >> possible at higher sample rates/higher channel counts. I should
mention
> >> that I am using Windows XP SP2.
> >>
> >> So far I have found nothing that allows my driver to control the size
or
> >> number of buffers that are passed in from the upper level driver. Does
> >> anyone have a solution to this problem? I'm sure there is something
> >> very
> >> basic that I am missing...
> >>
> >> Thank you,
> >>
> >> David
> >>
> >> ******************
> >>
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> >>
> >
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