[wdmaudiodev] Re: Audio control for recording not possible???
- From: "Jerry J. Trantow" <Jerry.Trantow@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Tue, 24 Sep 2002 10:50:52 -0500
I was going on the assumption that the OS did not support volume
controls for the record volume. You have a good point distinguishing
the difference between mixer api and control panel.
If the control panel supports it, he only needs to correctly implement
his firmware. If the control panel doesn't but the mixer api does
support the record volume control, he could write his own control panel
to handle this control. You are certainly correct that this would be
much easier than the filter driver option I laid out. The filter driver
is the last option if the built in facilities don't support it.
Have you implemented a feature unit on an input? Does the mixer API
support it under all OS?
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Paul V Wysocki
Sent: Tuesday, September 24, 2002 10:24 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: Audio control for recording not possible???
Jerry,
I think you are making this more complicated than it needs to be. If
Ajai's Audio Control Descriptor specifies a Function Unit with a volume
control between his Mic Terminal Unit and his Wave audio Terminal Unit,
then the Windows Mixer API will show him a volume control slider that
will send the usb audio class commands on control endpoint zero to set
the volume for recording. One note on this, you need to implement the
GET_MIN, GET_MAX, GET_CUR, and SET_CUR commands for the audio class
driver to actually implement the mixer. If your firmware sends a stall
for these commands, then windows will assume that the feature unit
doesn't exist, and won't show the slider in volume manager.
However, if the intent is to control the volume from within the device
itself, this is even easier as long as you don't need to notify windows
that the volume changed. If windows needs to know, then you probably do
want a HID device, but if windows doesn't need to know, then you can
react to the button presses on the cypress board and change your volume
level before you send the digitized audio to the isochronous endpoint
fifo.
Am I missing something? This seems much simpler than a filter driver to
build custom volume controls to replace the standard volume controls. I
can see where a filter driver would be useful for implementing volume
(or other) controls that the standard usbaudio.sys doesn't handle
correctly, but wave recording volume shouldn't be a problem.
-Paul
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Jerry J. Trantow
Sent: Tuesday, September 24, 2002 9:11 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Cc: ed.stroup@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: Audio control for recording not possible???
My understanding of your problem is that the Windows multimedia control
panel doesn't have a control for sending record volume information to
your device. Your device firmware implements the audio control, but
there isn't a built in way to get information to it.
Filter drivers are a method of adding functionality to the existing
drivers. My suggestion is to write and install a filter driver
(probably on top of usbaudio.sys) that would translate IOCTLs from
DeviceIOControl into the appropriate usb messages for the audio control.
You would also need to write a simple control panel that would call
DeviceIOControl to send the messages.
The control panel is very simple code. You need to monitor the
PlugNPlay of appropriate devices and send a few IOCTL messages. Ideally,
you write this as an automation server so people can use VB or Java
scripts to control it.
The filter driver simply translates the IOCTLs into the appropriate usb
commands for your device. The DDK has a bunch of UsbBuild macros which
make it easy to put the usb command together.
My experience has been that the biggest problem is supporting all the
peculiarities between different OS especially when it comes to
installing drivers.
I have done several contract jobs similar to this. If you are
interested in contracting out this work we should take this discussion
out of wdmaudiodev. jtrantow@xxxxxxxxxxxxxxxxxxxxxxxxxxx
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Ajai James
Sent: Monday, September 23, 2002 7:34 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: Audio control for recording not possible???
Hi Jerry,
Thanks a lot for your suggestion and help. Can you explain a little bit
more? So do I need to use a custom made application(like control pannel)
to change the volume of the recorded file? This control communicates
directly with the filter driver which in turn communicates with the USB
audio control firmware which should change the DAC out put
amplification, is it that way? Also, is there any way posible to be in
the firmware framework alone, and change the volume, without modifying
or adding the host driver part? Thanks to you a lot again.. Ajai
ajaijames@xxxxxxxxx "Jerry J. Trantow" wrote: You can always write and
install a filter driver which communicates to the audio control. Then
use DeviceIOControl from some type of control panel to send messages to
the driver which converts it to the appropriate USB command.
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Ajai James
Sent: Monday, September 23, 2002 1:54 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Audio control for recording not possible???
Hi friends,
I am using an Ez USB board to prepare a demo audio project.I have a
requirement to increase the volume of my recorded wav file depending on
the buttons on my kit, ie vol up and down. The enumeration is ok now,
and the firmware keeps on pumping the hard coded sine tone values to the
host.So, after selecting th enumerated board as a recording device, I
can record the sine tone. Now, i want to change the volume of the sine
tone using my boards f1, f2 push buttons. I thought I could use the
control end point with Vol up, vol down for that. But it does not seem
to work. On going through microsoft documentation
,http://www.microsoft.com/hwdev/tech/input/audctrl.asp
it seems that audio controls are supported for play back only, not
recording.. Am i correct in this assumption? any way to implement this
without using the audio controls
Thanks a lot, for your kind suggestions and comments ...
Ajai James
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