[wdmaudiodev] Re: Why windows Me is different from Win98 & Windows 2K/XP

  • From: "DJ Sisolak" <dsisolak@xxxxxxxxxxxxxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Wed, 26 Mar 2003 15:11:17 -0800

You are correct. In the WinME "Real Time" path, the usbaudio.sys driver
submits empty buffers to USBD and fills them afterward.

DJ

This posting is provided "AS IS" with no warranties, and confers no
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-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of BlazeAudio
Developer
Sent: Wednesday, March 26, 2003 3:12 PM
To: wdmaudiodev@xxxxxxxxxxxxx; wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: Why windows Me is different from Win98 &
Windows 2K/XP

 Perhaps DJ can provide more detailed information, but I'm suspecting
that
the USB Audio Driver is writing the data in the buffers *after* it
submits
the buffers to the USBD.

Or could it be possible that the USBD now supports "cyclic" isoch.
buffers
(like the 1394.sys does) allowing a client to send a request once, and
then
keep on refilling the same buffers?

Thanks.
Devendra.

At 05:32 PM 3/24/2003, Srinivasa Deevi wrote:


Hi all

 I have to modify the USB data that is coming from
 microsoft USB audio driver and convert to different
 format before sending to our device. The concept
works
 fine in Windows 98 and Windows 2K, XP with out any
 problem . In case of windows Me , when the Transfer
 buffer of URB request contains Zeros always . If I
 don't touch the data buffer in URB then I can see
some
 data coming out of Iso pipe . And I don't see any
problem when I am sending the data up through Iso IN
pipe. The problem occurs only on Iso OUT pipe .


Thinking that it could be related to "realtime "
mixing capabilities of WinMe, I checked for all the
IOCTLs that are coming for USB audio . But I could
never find any request that is related to "real time"
as shown below.

"
This indeed is happening because of the "realtime"
negotiation that happens
between kmixer and usbaudio. To circumvent this
behavior, you should fail
the property KSPROPERTY_RTAUDIO_GETPOSITIONFUNCTION in
the property set
KSPROPSETID_RtAudio.

#define STATIC_KSPROPSETID_RtAudio\
0xa855a48c, 0x2f78, 0x4729, 0x90, 0x51, 0x19, 0x68,
0x74, 0x6b, 0x9e,
0xef
DEFINE_GUIDSTRUCT("A855A48C-2F78-4729-9051-1968746B9EEF",
KSPROPSETID_RtAudio);
#define KSPROPSETID_RtAudio
DEFINE_GUIDNAMED(KSPROPSETID_RtAudio)

typedef enum {
KSPROPERTY_RTAUDIO_GETPOSITIONFUNCTION
} KSPROPERTY_RTAUDIO;

This is a private interface between kmixer and
usbaudio, there is no
guarantees that this won't change in the future.
Please only override this
functionality in extreme cases. Without this
interface, the performance of
usbaudio is severely impacted."


Am I missing something here or where should I check
exactly check or modify the real time settings for
Windows me .


thanks in advance
sri.


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