[wdmaudiodev] Re: Change default sound format with an inf File in Win7

  • From: Ueli Giger <giger@xxxxxxxxxxx>
  • To: wdmaudiodev@xxxxxxxxxxxxx
  • Date: Tue, 23 Feb 2010 13:51:08 +0100

Tim Roberts schrieb:
Ueli Giger wrote:
My goal is to change the default format of a USB soundcard by the
installation over the inf file.
I work with an USB Audio Codec from TI (PCM2904) and for our application
we need  the default format Stereo, 16 Bit, 44100 Hz.

Why don't you just change the descriptors in your device to make that
the only available format?  You can even do that in a lower filter driver.

What's the point of this change?  If you're offering other formats, why
do you not want people to use them?
That's a good idea cause I only want to make the format Stereo 16Bit 44100 Hz, but how can I do this? My problem is that I've no experience in programming a lower filter driver. Can you give me any good
links or examples?

The soundcard installs standardly the standard usb audio device driver
with the wdma_usb.inf.
My idea was now to modify the wdma_usb.inf according to these two
discussions to change the default format:

Never, never, never change one of the system's standard INF files.  I'm
surprised someone even has to point that out to you.

It is possible to use a custom INF file for a USBAudio device, but it's
pain to do so.  Users must pre-install your driver before plugging in
the device, otherwise the standard USBAudio driver will claim it.
I know that I never should change the system's standard INF files. Sorry my description above wasn't
very precise. Here a more detailed description of my problems:
We use a USB Audio Codec (PCM2904 from TI) to sample data from a radar sensor to LabView. Now we've tested the software, which runs correct under XP, under Win 7 and noticed that there are two

Problem 1:
When you plug in the PCM2904, Win7 finds the USB Audio Codec and installs it with the default format Mono, 16 Bit, 44100 Hz. But we need the format Stereo, 16 Bit, 44100 Hz. To solve this problem my idea was to copy the standard .inf file and add the lines for the default format and then install
this driver over the standard usb audio driver.

Problem 2:
Under Win7 we have an additional gain of +40dB against the measurements with win XP. When I change the format over the control panel when the LabView application is running, the gain disappears and the
measurement is the same as in XP.
What could be the reasons for this gain? And how can I bypass my signal without any gains?

You're aware this solution is only for Vista and newer, right?

Yes I know that this is so.


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


Other related posts: