[wdmaudiodev] Re: DMA mode?

  • From: Pallavi Joshi <pallavi.v.joshi@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Tue, 11 Aug 2009 17:54:00 -0700

I meant the kernel streaming buffers that I am handing to usbaudio.sys
through IOCTL_KS_WRITE_STREAM.
Yah, I know I can't overwrite them. The problem is that the playback(render)
takes much longer than the capture operation. Hence the overwriting issue. I
wanted to speed up the playback operation by using DMA buffers, but that is
already in place looks like!

Anyways, thanks a lot for replying.

Pallavi





On Tue, Aug 11, 2009 at 5:45 PM, Tim Roberts <timr@xxxxxxxxx> wrote:

> Pallavi Joshi wrote:
> >
> > Yup, I meant reducing the latency! Thanks so much for replying. This
> > is easy then :)
> >
> > The main issue that I am facing is that I overwrite the playback
> > buffer with new data before my previous data has finished playing.
> > This is what MSDN documentation says about asynchronous IO:
> > "Do not deallocate or modify the OVERLAPPED structure or the data
> > buffer until all asynchronous IO has been completed."
> >
> > Due to this, I get missing data in my audio stream. Do you have any
> > suggestions?
>
> I'm not sure, you have a lot of concepts mixed up here.  Which playback
> buffer are you overwriting?  Is it the application buffer that is being
> handed to your ASIO driver?  Is it the kernel streaming buffers you are
> handing to usbaudio.sys through IOCTL_KS_WRITE?
>
> The advice is good: you can't start reusing a buffer until you know the
> guy beneath you is finished with it, but the exact definition of
> "finished with it" depends on which level you're at.
>
> --
>  Tim Roberts, timr@xxxxxxxxx
> Providenza & Boekelheide, Inc.
>
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-- 
Pallavi Joshi
(480)-280-2017

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