[wdmaudiodev] Why windows Me is different from Win98 & Windows 2K/XP
- From: Srinivasa Deevi <srinivasadeevi@xxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Mon, 24 Mar 2003 17:32:08 -0800 (PST)
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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