[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
resolution?
> 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,
Bart
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