[wdmaudiodev] Re: USB Audio synch. mechanism
- From: "DJ Sisolak" <dsisolak@xxxxxxxxxxxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Wed, 14 May 2003 13:15:56 -0700
Hello Devendra,
If USBD creates such an API, then USBAudio will definitely try to take
advantage of it. At this point I cannot tell you when or if that may be.
Even if such an interface is created it would still be useful only to
Adaptive and Sync endpoints since it would be nearly impossible to
continually adjust the transfer descriptors on the exposed transfer
buffer to account for feedback for Async.
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, May 14, 2003 10:57 AM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] Re: USB Audio synch. mechanism
Hi DJ,
That makes a lot of sense!
Also, is the new usbaudio.sys going to use WaveRT port - would be
possible
ifUSBD provided a cyclic DMA based mechanism (like the 1394.sys)?
Thanks.
Devendra.
At 09:37 AM 5/14/2003, DJ Sisolak wrote:
Hello Devendra,
The error with async endpoints has to do with the timeliness of the
updating of the sample rate based on the data from the feedback
endpoint. Technically it will work with all OS's back to Win98, but only
recently have I fixed the timing.
Thanks,
DJ Sisolak
Microsoft Corp.
This posting is provided "AS IS" with no warranties, and confers no
rights.
-----Original Message-----
From: wdmaudiodev-bounce@xxxxxxxxxxxxx
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx[1]] On Behalf Of BlazeAudio
Developer
Sent: Tuesday, May 13, 2003 7:11 PM
To: wdmaudiodev@xxxxxxxxxxxxx
Subject: [wdmaudiodev] USB Audio synch. mechanism
[OOPS! I'd posted this message with incorrect subject!]
The "USB Audio and Windows" whitepaper (available from
http://www.microsoft.com/whdc/hwdev/tech/audio/USBaud.mspx[1[2]]) says:
"Starting with Windows 98, Usbaudio.sys supported the adaptive and
synchronous endpoints, but it did not implement the asynchronous
endpoint
correctly. Full support for asynchronous endpoints in Usbaudio.sys is
plannedfor Windows Longhorn."
However, I have implemented async. isoch. synch. mechanism on two
different
devices - and it has worked perfectly - starting from Windows 98 SE.
What's not correct about the implementation?
Thanks.
Devendra.=3D20
--- Links ---
1 http://www.microsoft.com/whdc/hwdev/tech/audio/USBaud.mspx[3]
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3 http://www.microsoft.com/whdc/hwdev/tech/audio/USBaud.mspx
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