[wdmaudiodev] Re: Hi,

  • From: "Jerry Evans" <jerry@xxxxxxxxxxx>
  • To: <wdmaudiodev@xxxxxxxxxxxxx>
  • Date: Sat, 28 Jan 2006 01:08:22 -0000

Hi Hakon,

Thanks for the update. I will be only too happy to use the exclusive mode if it 
performs as well as we all hope.

Does the Vista exclusive mode make any promises about latency? Given the 
overhead with the current USB stack is it realistic to expect latencies in the 
order of 6-8ms round-trip? Is this mode and its API documented yet ? 



----- Original Message ----- 
  From: Hakon Strande 
  To: wdmaudiodev@xxxxxxxxxxxxx 
  Sent: Friday, January 27, 2006 6:34 PM
  Subject: [wdmaudiodev] Re: Hi,


  We are not doing anything directly to break DirectKS in Vista although we as 
you indicate did state in the past (when DirectKS was born) that we did not 
guarantee that this model will be maintained for future OS. 

  To update that disclaimer, DirectKS should still work in Vista with 
appropriate audio driver models although I am not sure it makes sense to use 
that model anymore since the Vista audio system is so much better than past OS 
with regards to latency, thread priorities, etc. We feel there is less need for 
audio content creation applications to bypass the Vista audio subsystem than 
has ever been the case before but if necessary there is a built in direct mode 
called Exclusive Mode that can be utilized. If you really want to though, I 
believe DirectKS can still offer that direct link as well. If you are a Vista 
Beta tester and find that DirectKS apps do not work, PLEASE file bugs.


  Hakon Strande

  PM Integrated, Internal, External, and Wireless Audio Devices

  MediaTech/DMD/Windows Client/Microsoft


  From: wdmaudiodev-bounce@xxxxxxxxxxxxx 
[mailto:wdmaudiodev-bounce@xxxxxxxxxxxxx] On Behalf Of Jerry Evans
  Sent: Friday, January 27, 2006 10:07 AM
  To: wdmaudiodev@xxxxxxxxxxxxx
  Subject: [wdmaudiodev] Re: Hi,

  Hi Nugen

  I'd qualify this by checking your latency requirements. If you need latencies 
of less than 20ms or so then it going to be very hard to do with the existing 
USB stack. 

  It is also wrth mentioning that the KS interface is likely to be dropped in 
Vista so the investment in time may be of limited value. Some of the Microsoft 
people here may be able to comment on this.

  A quick way to test latency and stability is to try ASIO4ALL 
(www.asio4all.com). This is an ASIO interface to KS. You can then use an ASIO 
compliant application like Cubase to test your hardware (or write something 
using PortAudio or similiar)

  Off the shelf USB drivers can be had here: 
http://www.thesycon.de/eng/usbio.shtml (I am not affiliated BTW). I believe 
that these will offer considerably better performance.



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