Explain WDM Drivers, Please!

  • Thread starter Thread starter bongolation
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bongolation

bongolation

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Other than the supposition that these are new developments to reduce latency, I don't know anything about 'em.

I do hear that they are unsupported in many common devices, so I figure I had better get up to speed with this before I buy the wrong thing again.

Thanks!
 
Well, simply put, they are a newer Windows system architecture for hardware drivers. The letters stand for Windows Driver Model. The technical reasons why it is (or should be) superior to the old MME (Multimedia extensions) are beyond my current knowledge...
 
Keep in mind I've never done any Windows development, but I went on Microsofts sight and looked up some white papers on WDM. Here's what I think they say.

The current method of handling audio streams uses DirectShow. DirectShow sits on top of the OS running at the same level as the application. If you need to send an audio stream from one device to another the stream must come from one device driver up to application or to DirectShow (at the application level) and then back down to the device driver of the second device.

WDM incorporates some of the DirectShow functionality directly into the device driver. This allows WDM to be much more efficient in handling audio streams because more of the work is being done at the device driver level. In addition this allows an audio stream to go directly from one WDM device driver to another without going to the application level. The two device drivers can even share buffers so that there's no need to copy the data. In fact the architecture allows for hardware devices to send data from one device to another without the need for any software intervention.
 
kaydis,

do you know how the kmixer figures into this stuff, the windows kernel mixer?

your post is really helpful!

j
 
OK, so I think WDM sounds like A Good Thing, but can you tell me which recording devices do/don't support the tech?

I believe someone said that SeaSound (which I _was_ going to buy) doesn't and has no plans to.

So, who does?

Thanks!
 
123

It is a kernal streaming technique that allows you to bypass windows plumbing and deal directly with the Kernel. The advantage is lower latency, better response time, real time effects, etc. It will be the new standard soon.
Seasound told me they would not support it because they are cheap bastards and pissed me off. Aardvark will have WDM drivers out this coming month, I think the Omnis already have it, and a few others. The only program I know of that supports WDM drivers so far is Cakewalks Sonar, which has some really nice features becuase of it, including directx8, which makes all your effects automatable.
 
I can't find too much info about kmixer other than its the Kernel Mixer (the kernel is the lower level of the OS responsible for controling resources like memory, scheduling programs to be run, etc). It sounds like kmixer is a part of the kernel that is responsible for mixing audio streams to be sent to an audio device. It also sounds like it is responsible for telling the hardwae what audio format to use. Beyond that its hard for me to determine exactly what it does do based on what little info I can find.
 
123

The Kernel is basically in charge of everything, we'll keep it at that for simplicity. In order for anything to "talk" back and forth between the processor, and operating systems, memory, hardware, etc, it has to do so through the kernel. Consider it the boss. When your hardware (soundcard) decides "hey, I need some audio processed" it sends it off. It then has to filter through all of windows wordy, slow plumbing and then wherever, and then to the processor and then back through all the same shit again to go back to the soundcard. WDM drivers permit the soundcard to communicate directly with the kernel, therby reducing the amount of bullshit it has to go through before it can be processed and sent on its way. Much faster, less latency. The idea here is to have instantly available effects. You move a slider, and it responds instantly. Also soft synths, these will eventually be just as fast as having a real synth sitting in front of you, and WAY WAY cheaper. Good benefits, make sure you move to WDM when you have the opportunity.
 
thanks for the info guys....this stuff is new to me...now that i've installed sonar and the delta 66 (with the omni), it works pretty cool...i was playing my guitar thru revalver and it sounds great..the latency is so small that you could consider recording this way...though, i just started playing around with this...i've never gotten a midi keyboard to work with a soft synth with as little latency as i'm getting playing guitar thru revalver..but then, my midi keyboard is pretty crappy...and i don't do a lot of midi...

i read something on the m-audio site about bypassing the k-mixer..that's what got me interested in the k-mixer....i was going to post a link to the doc, but i couldn't find it again on the m-audio site...it basically said that microsoft accepted a way to bypass the k-mixer and that you should ask your software manufacturer how they are dealing with this issue...however, this may be something that has already been implemented in sonar and the delta drivers...that is what i was wondering about...

the soundblaster live is supposed to have wdm support, so i'm going to install one in a couple of days and see how it works with the soft synths in sonar..

if anyone has anything else to say about the WDM drivers i think others besides myself would be interested.

thanks again, even though i didn't start this thread
 
Does The Lynx One card have it or will...?

You really gotta be on top of this audio stuff.
Sounds good though...
 
PRiZ,

you made me curious about the lynx one, so i wrote the manufacturer. the response i got is that there are plans to support WDM under Windows 2000 and Windows XP. however, they have no release dates or announcements to make at this time.
 
thanks...

They apparently have really good service, so I believe it will come fairly soon.
 
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