[wdmaudiodev] Re: USB audio device question

  • From: Pallavi Joshi <pallavi.v.joshi@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Wed, 17 Jun 2009 17:50:32 -0700

I have written all this in a ASIO driver and I am using Ableton LIVE to play
music. The buffer size is 512 right now. So basically inside the start()
function of the ASIO driver, I get the input samples (512) and then play the
output samples obtained from the bufferSwitch callback of the host (Ableton
LIVE). So this keeps repeating as long as ASIOStop is not called.

I hope this is making sense.

Thanks fro your help,

On Wed, Jun 17, 2009 at 5:26 PM, Tim Roberts <timr@xxxxxxxxx> wrote:

>  Pallavi Joshi wrote:
> >
> > I have a USB audio device and I enumerate the device, get the file
> > name and create a handle to it using the CreateFile function. I then
> > use kernel streaming (from the DirectKS sample by MS) to communicate
> > with this USB device. I basically first instantiate a capture and a
> > render pin on the filter using the KsCreatePin function from
> > ksuser.dll. I then use DeviceIoControl function with
> > write data from my USB audio device. But the audio playback I hear is
> > not good....in the sense its quality is not good. If I play a sine
> > wave it sounds broken as if parts of its data are missing. I used a
> > USB analyzer to see the USB frames which are being sent and received
> > every 1 ms. Here the input frames from the USB are good but the output
> > frames going to the USB have "zero packets" periodically. This might
> > explain why my audio quality is not good and broken.
> >
> > Can anybody tell me why is this happening? Any pointers will be of
> > immense help to me.
> How are you sending the sine wave data?  How large are the buffers, how
> often do you send them, how are you doing the pacing?
> --
> Tim Roberts, timr@xxxxxxxxx
> Providenza & Boekelheide, Inc.
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Pallavi Joshi

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