[wdmaudiodev] Re: MediaPlayer improves USB DPC timing

  • From: "Martin Puryear" <martinp@xxxxxxxxxxxxxxxxxxxxx>
  • To: <bart@xxxxxxxxxxxxx>
  • Date: Fri, 25 Jul 2003 02:40:49 -0700

MPlay32 is included in Windows; this ought to be quick'n'easy to try, and it 
uses just the basic MCI APIs.

The timeBeginPeriod may be what you want - this should be in the Platform SDK 
and various samples.  

For kernel-mode, please read the documentation on ExSetTimerResolution in the 
Windows DDK.  Do not misuse this DDI - it can severely affect overall system 
performance and may shorten system bettery life.  This particular DDI still 
exists mainly because it is not abused.

Martin Puryear
Development Manager
Microsoft Windows Audio/Video Devices Group

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-----Original Message-----
From: bart@xxxxxxxxx [mailto:bart@xxxxxxxxx] On Behalf Of bart@xxxxxxxxxxxxx
Sent: Friday, July 25, 2003 2:11 AM
To: Martin Puryear
Cc: WDM list; Ron Kuper
Subject: Re: MediaPlayer improves USB DPC timing

Hi Martin,

> As far as I know there is NOTHING in Windows Media Player that uses 
> anything other than fully documented OS services.  This should not be 
> at all surprising since WMP is legally considered middleware by U.S. District 
> Court.  There's no leeway here.
I assume it is my lack of knowledge being unable to explain what I measured, 
therefore I thought I should ask the list.

> It's actually a little funny to hear you suggest a cozy relationship 
> between the WMP team and the kernel audio team.  It isn't like that.
I didn't want to suggest this, sorry if you got this impression. My attempt was 
to state the facts I saw and try to understand what's happening.

> Back to the topic.  I suspect, if anything, WMP uses the venerable 
> Time APIs to turn up the timer resolution; I don't know for sure.
Could you point me to a link where it is described how I can turn up the timer 

> Maybe it isn't WMP at all, though - have you tried RealPlayer or 
> MusicMatch, or even MPlay32?
Not these two, but I also tried Cubse SX and the issues are the same. I assume 
that if there where settings like that a high quality 'reference' program 
written by very experienced programmers like Cubase SX would have these right. 
I'll try other programms.
Do you know where I can find information on how to optimize XP's kernel timing?

> There is code in the WDM audio stack that tries to make the system 
> work better for all multimedia apps.  It's probably that, as opposed 
> to anything from a user-mode client like WMP.
Can you point me to a link with more information on this?

Best regards,


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