[wdmaudiodev] Re: KSPROPERTY_STEPPING_LONG problem!
- From: Tim Roberts <timr@xxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Wed, 31 Mar 2010 09:45:06 -0700
eric wrote:
>
> After a quick experiment, using KSPROPERTY_MEMBER_RANGES makes the
> volume control disabled. I found Mark ran into the same problem before:
> //www.freelists.org/post/wdmaudiodev/Setting-upper-and-lower-volume-bounds,
> and
> what Michail said seems to refer to the same scenario. Nevertheless, I
> still believe there is an answer in front of us, if any body had this
> issue solved or just had a normal behavior luckily in avstream
> architecture and under XP sp2, please leave a messge to us~
Allow me to make a suggestion. The numbers in the volume control are
supposed to be physical units, in decibels/65536. You are specifying
very, very tiny amounts, and all on the amplification side, not the
attenuation side. Most volume controls are just attenuation, so that
their controls have a range that is entirely on the negative side, and
perhaps some part of the XP audio stack makes that assumption.
Try this. Pretend that your range is actually -40 dB to +9 dB. So,
make the minimum 0xFFC80000, the maximum 0x00090000, and the step
0x00010000. Then, in your volume set handler, convert that to your
numbers by doing:
iOrdinal = ((int)iPropValue >> 16) + 40;
and in your volume "get" handler, convert like this:
iPropValue = (iOrdinal - 40) << 16;
--
Tim Roberts, timr@xxxxxxxxx
Providenza & Boekelheide, Inc.
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