Yes, the data format is supported by my USB. I think I understand what you mean by data starving and that is what is happening in my case. I am not sending multiple buffers. I do not have any timer callbacks. I don't know much about them! I will try and figure out how to do this timer stuff. So I need a timer callback to tell my output device that the data is ready to be sent? Thanks a lot for pointing it out. Regards, Pallavi On Tue, Jun 23, 2009 at 5:26 PM, Tim Roberts <timr@xxxxxxxxx> wrote: > Pallavi Joshi wrote: > > I am feeding the data using DeviceIoControl with IOCTL_KS_WRITE_STREAM > > as the control code. The render pin is created using the KsCreatePin > > function from ksuser.dll. The buffer size is 512 and it is a 2 > > channel, 16 bit PCM audio data. The sampling rate is 44.1 KHz. > > Its exactly the same way as it is done inside the DirectKS sample code. > > I do not know what you mean by two things: "timing" and "mismatch in > > data performance"? > > Well, I wrote "data performance" when I really meant "data format"... > Are you sure that your USB device accepts 44100 stereo 16-bit PCM? (It > probably does -- it's a common format.) > > An audio device is a real-time device. It consumes data continuously. > If you don't have more data in the queue when it runs out, the device > will "starve", and you get a short period of silence, which makes the > sound choppy. A 512-byte buffer will only keep your device fed for 3 > ms. Are you sending multiple buffers down so that the device never > starves? How do you guarantee that there is always data waiting? Timer > callback? > > -- > Tim Roberts, timr@xxxxxxxxx > Providenza & Boekelheide, Inc. > > ****************** > > WDMAUDIODEV addresses: > Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx > Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe > Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe > Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx > > URL to WDMAUDIODEV page: > http://www.wdmaudiodev.com/ > > -- Pallavi Joshi (480)-280-2017