[wdmaudiodev] Re: IMiniportWaveCyclicStream::SetFormat() insists on Stereo instead of Mono
- From: "Don Bell" <0dbell@xxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Fri, 4 May 2007 14:59:29 -0500
BTW, I did trace back the source of this "uncalled for" conversion and
it shows up as early as CMiniportWaveCyclic::NewStream().
Since I never call this function directly, I must assume that it is a
system callback in response for some WaveXXX (or DirectSound) API (it
is actually an implementation of the IMiniportWaveCyclic::NewStream()
interface).
It seems that the audio system decides to convert the mono signal to
stereo in order to support simultenaous output to both speakers.
But... if I have only one "speaker", how do I tell that to the system?
I tried modifying MAX_CHANNELS_PCM in simple.h from 2 to 1, but all it
did was trunctaing alternate frames by half - which is even worse than
having consistently duplicate stream.
Any idea?
Thanks,
Don
On 5/4/07, Don Bell <0dbell@xxxxxxxxx> wrote:
I have written a virtual audio driver based on MSVAD. It works but...
when I try to play through Sound Recorder a Mono .wav file, "somebody"
(either Sound Recorder or the driver itself) insists on setting
nChannels = 2 (instead of 1) in
CMiniportWaveCyclicStreamMSVAD::SetFormat().
I can see this clearly in the debug trace.
Why???
Is there a rule that states that every Mono signal needs to be
converted on playback to Stereo? (so that in sounds equally on both
speakers, giving the illusion of mono)?
How do I force the driver to always set nChannels = 1 (mainly to cut
bandwidth requirements to half, but also to simplify frame handling).
I would appreciate any tip or hint in the matter.
Many thanks in advance,
Don
******************
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/
Other related posts:
