[wdmaudiodev] Re: modes vs. gains: caching?
- From: Hock Yiung HUANG <hyhuang@xxxxxxxxxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Mon, 12 Jun 2006 14:27:29 -0700
> Is this correct? If so, it would seem our mini-driver needs to send some
> kind of message up through the audio stack to invalidate the cache, but we
> don¹t know what that message might be.
Try implementing the <KSEVENTSETID_AudioControlChange, KSEVENT_CONTROL_CHANGE>
event support on the
volume control node. The KSEVENT_CONTROL_CHANGE event indicates that a change
in control value has
occurred at a node.
-HockYiung
wdmaudiodev-bounce@xxxxxxxxxxxxx wrote on 06/12/2006 11:40:01 AM:
> We¹re having a little trouble dealing with a Windows mixer corner case in a
> control panel.
>
> We¹re building a somewhat odd audio device which has a single audio input
> socket which may operate in one of two modes at any given time. The mode is
> selectable via software, but it could just as easily be selectable by
> hardware. Each mode has a slightly different gain structure. Marketing has
> decided that the product should remember the gain for each mode, and when
> the user switches between from mode A to mode B, the panel should likewise
> update its single fader from the gain of mode A to the gain of mode B.
>
> The trouble is that when the panel queries the Windows mixer control for the
> gain in mode A, changes to mode B, and queries again for the gain, the
> driver appears to be prepared to report gain B, but the panel obtains gain A
> as if the mode had not been switched. We suspect there is some caching going
> on such that the Windows mixer does not realize we¹ve changed the mode ? and
> even if it did it wouldn¹t know what that change meant anyway ? and it¹s
> trying to save somebody time by not querying the driver again for its gain.
> Is this correct? If so, it would seem our mini-driver needs to send some
> kind of message up through the audio stack to invalidate the cache, but we
> don¹t know what that message might be.
>
> In any case, does anybody have any ideas how to solve this problem which
> doesn¹t involve trying to talk Marketing out of this feature? :-)
>
> --
> Mark Cookson
> Software Tech Lead
> M-Audio, a part of Avid
> 225 Locust St.
> Hudson, WI 54016
>
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