[wdmaudiodev] Re: USB audio device question

  • From: Tim Roberts <timr@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Wed, 17 Jun 2009 17:26:09 -0700

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
> IOCTL_KS_READ_STREAM and IOCTL_KS_WRITE_STREAM  codes to read and
> 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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