[wdmaudiodev] Re: My first WASAPI implementation.
- From: "Jeff Pages" <jeff@xxxxxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Thu, 23 Mar 2006 10:35:29 +1100
As card manufacturers we have no control over how third-party applications
expect to see our hardware. If application X wants to open four stereo channels
to generate 8 outputs then our card has to allow that, but if application Y
expects to see a single 8-channel device then we have to support that too.
Otherwise the customer goes away.
Jeff Pages
Innes Corporation Pty Ltd
----- Original Message -----
From: Perry, Chris
To: wdmaudiodev@xxxxxxxxxxxxx
Sent: Thursday, March 23, 2006 9:54 AM
Subject: [wdmaudiodev] Re: My first WASAPI implementation.
>then it is appropriate for the device to be presented as several completely
independent sets of outputs.
As far as I can see, this is only appropriate if the speakers you are talking
about are attached to two separate audio devices. If they are attached to
channels from a single audio device such as a MOTU then the
application can mix the audio stream on each channel to go to whatever
speaker desired.
So, to me, it seems that you can get there if all channels on one device can
be opened and used at once. However if Vista presents the device as stereo
pairs than I have to open each pair as a separate "virtual" device and then
issue a play for each "virtual" device which presents a problem if you want to
output to all channels simultaneously.
Chris Perry
Bose Corporation
------------------------------------------------------------------------------
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Frank Yerrace
Sent: Wednesday, March 22, 2006 5:03 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: My first WASAPI implementation.
> We do it in order to support legacy apps that don't support multichannel
hardware.
The API layers do this on your behalf. For example, the application can open
stereo formats using waveOut regardless of how many channels the actual audio
hardware has. The stereo data ends up being directed to the two output channels
identified as front-left and front-right.
> Plus, it lets you address different sets of inputs and outputs with
multiple applications simultaneously, which is useful.
If the user wishes to configure his device installation to have two channels
going to one set of speakers and other channels going to other sets of
speakers, then it is appropriate for the device to be presented as several
completely independent sets of outputs.
What Vista currently does not promote is a hybrid between these two
configurations, allowing apps to discover for example 4 stereo devices *and*
one 8 channel device. At this time, we don't understand how this is a useful
feature going forward. I'd like to understand more about this sort of usage if
others feel this is a problem.
Frank Yerrace
Microsoft Corporation
This posting is provided "AS IS" with no warranties, and confers no rights.
------------------------------------------------------------------------------
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Matt Gonzalez
Sent: Wednesday, March 22, 2006 1:13 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: My first WASAPI implementation.
We do it in order to support legacy apps that don't support multichannel
hardware.
Plus, it lets you address different sets of inputs and outputs with multiple
applications simultaneously, which is useful.
Matt
wdmaudiodev-bounce@xxxxxxxxxxxxx wrote:
I never really did understand why vendors would publish a bunch ofstereo pairs
rather than one device that had many channels. Was this tosupportlegacy OS's
that didn't have WAVEFORMATEXTENSIBLE? If I have one 8-channel stream I want
to output, the last thing I wanttodo is open 4 virtual stereo devices and
issues the play command to eachone. Chris PerryBose Corporation -----Original
Message-----From:
wdmaudiodev-bounce@xxxxxxxxxxxxx[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On
Behalf Of Frank YerraceSent: Wednesday, March 22, 2006 3:36 PMTo:
wdmaudiodev@xxxxxxxxxxxxxxxxxxxx: [wdmaudiodev] Re: My first WASAPI
implementation. my biggest gripe currently is not knowing if its possible
for a device manufacturer to define a huge 16 output (or more) endpoint in
oneIAudioClient without having to fake it with WAVEFORMATEXTENSIBLE'snChannels
set to 16 and dwChannelMask set to 0x00, or to have thatmanufacturer define a
bunch of separate stereo pairs to do the job. Can you clarify what you would
*like* to see here? At this time, we feelthat if the hardware is intended to be
used as a 16-channel output, thenit should be presented as a single 16-channel
output accessed through asingle instance of IAudioRenderClient using a
16-channelWAVEFORMATEXTENSIBLE. Frank YerraceMicrosoft Corporation This posting
is provided "AS IS" with no warranties, and confers norights -----Original
Message-----From:
wdmaudiodev-bounce@xxxxxxxxxxxxx[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On
Behalf Of David ViensSent: Wednesday, March 22, 2006 12:17 PMTo:
wdmaudiodev@xxxxxxxxxxxxxxxxxxxx: [wdmaudiodev] Re: My first WASAPI
implementation. Ron Kuper wrote: David, were the "suprises" pleasant or
unpleasant? Ha, of course I meant "surprisingly good" results,with little
to no clicking (but sometimes occurring with evenmoderate DSP cpu loads) I ran
the code with my onboard NVidia AMD nforce4 ac97,a Roland ua-1a device running
"USB composite device",and my Terratec EWS88MT's extra output (fixed at 48
Khz)- not the full 12/10 combo which doesnt appear.cant try my various SB
cards, because of lack of working drivers. I'm trying to put latency down, but
i got tired of shooting in the darkwith trying things. Thats why i'm awaiting
answers before continuing.Knowing that vista is now scheduled to release in
2007, its not thaturgent it would seem.The way it currently works is a bit odd,
with the 100-nano second"periods"settings, which cant seem to fit on even
sample frames in somecircumstances,or .. sigh allow for power of two sized
buffers. Also since no pro audio card has Vista drivers yet, my biggest
gripecurrentlyis not knowing if its possible for a device manufacturer to
define ahuge16 output (or more) endpoint in one IAudioClient without having to
fakeit withWAVEFORMATEXTENSIBLE's nChannels set to 16 and dwChannelMask set
to0x00,or to have that manufacturer define a bunch of separate stereo pairs
todo the job. (i never implemented WDM-KS's pin querrying stuff mind you - so
might bea similar thing) I've got another bag of questions...
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