[wdmaudiodev] USB audio device question

  • From: Pallavi Joshi <pallavi.v.joshi@xxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Wed, 17 Jun 2009 17:02:00 -0700

Hi All,

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.

Thanks very much,

Pallavi Joshi

Other related posts: