|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
207.216.246.51
In Reply to: Understanding "Do not map through this device" option posted by PM on March 4, 2007 at 06:47:20:
PM:This is a good question. I honestly thought "I should know this" but when it came time to write, I realized I really didn't know.
So off to the computer I went. For this "test" I used a Creative X-Fi Xtreme music, which has "multi-headed" (dual) WDM/ASIO drivers. I am currently trying many iterations with this card, and after some experiementing, I found I can get really good SQ out of it!
So I went to the device manager and selected the "SB" (soundblaster) device and checked the "Do not map" box. Rebooted. Ran my soundcard in both ASIO and kernel streaming/WDM mode. Got sound in both cases. That's strange? RIght? Not really. In MY case this sound card is NOT THE WINDOWS DEFAULT SOUND DEVICE (I have an onboard C-media selected for my onboard sound device so all windows sounds get mapped THERE. I also have sounds DISABLED for extra protection because I am "bit-perfect-obsessed paranoid and delusional audiophile").
I think "Do not map" is when you have a particular audio device selected as a Windows Audio device somewhere, and you are telling it not to map "windows sounds", such as voice, system notification sounds, etc. through the device. I *THINK* this is what they mean by *MAP* - it means "Do not map the 'digitally mixed' output of the kmixer through this device". But I could be wrong here.
I will experiment with this further. Because I am using either ASIO or Kernel Streaming, I figured that "Do not Map" would have no effect - and it did not. I think this "do not map" only matters when the device is SELECTED and OPERATIONAL as a Windows Audio Default device for playback, midi or speach.
Now as for "Use features on this device"... that's a whole other ballpark. When you select THAT bullet, you will also notice that it changes AUTOMATICALLY the following settings:
"Do not use mixer features of this device" under "Mixer Device".
"Do not use midi features of this device" under "Midi Device".Interesting. Three different settings, but ALL are disabled by the FIRST setting. Hmmmm... that's NEEDLESSLY CONFUSING! lol
In any case, I selected the "Do not use" bullet (and UNchecked do not map). Strange results: I got Kernel Streaming to work but not ASIO! It seems I need the devices "mixer" functions of the card to use ASIO (The Creative mixing "Console" [active in 'Audio Creation Mode'] is disabled when the "Do not use" button is checked). But I am confident this "DSP Mixer" is NOT one in the same with the "dreaded Windows Audio Kmixer". Even the best top dollar cards have a DSP "mixer" - but they are typicall an "ASIO only" driver. Some mid-fi / pro-sumer ones (like the M-Audio Revolution 5.1/7.1) are "multi-headed" meaning they can operate in both WDM and ASIO modes. Ah, the confusing joy of Audio under Windows.
A word on Kmixer: Kmixer is a very generic term for a part of the Windows Audio Stack. There are different versions of the Windows audio "system" - there is the older AC97 spec (which resampled the hell out of everything and everything - I think to 48khz if I am not mistaken). And then there are newer variants - the Intel HDA (High Definition Audio) "Azalia" spec for onboard Hi-Def / Hi-res capable codecs like the Realtek ALC880 or the Cmedia CMI9880.
Enter Vista. Realtek has come out with a ALC888, and Cmedia has come out with some new fandagled DSP software for the CMI9880 platform called "Hydrogen". (Seems like a simliar direction of the "Oxygen" 8787/8788 PCI cards.)
Microsoft seems to be handshaking with the "media" giants for onboard codecs, but a lot of PCI card vendors are still shrugging their shoulders when asked about Vista drivers. I say if you're kernel streaming or using ASIO under XP, be happy for a few years until the bugs are ironed out of Vista (with respect to audio AND in general).
Let's face it. XP is NOT a bad OS if it's configured and streamlined correctly. Vista promises better multi-media.
One thing to be aware of: todays "multi-media" is more about compatibility with the latest multichannel formats, and conformance to new DRM requirements than it is about SOUND QUALITY. Microsoft is so DRM happy (with audio AND computer software) you're soon going to need to insert a DNA sample into your computer just to turn it on.
I'm sticking with Foobar, Winamp, ASIO and KS plugins, Aedio Japan crossovers, and the 64 bit *math* Thuneau Allocator/Arbitrator.
I'd need to do some serious component upgrades to my speakers and amps before getting a "better" digital front end is going to make an appreciable difference.
So there you have it. Use ASIO or Kernel Streaming and those settings are a mute point. Either ASIO or Kernel Streaming will result in exclusive access to the audio device. In fact, a few folks have COMPLAINED that when using Kernel Streaming or ASIO output plugins they lose all other Windows "system sounds".
Well duh guys. That *was* the whole POINT! :o)
Follow Ups:
Well I fooled around with it a little more and here's what I think -I was also of the impression that "Do not map..." will prevent "windows sounds" (popups, alerts, ding dong etc..) to that audio device. However that is NOT the case. I tried that option and Windows Sounds go right through that device when it is busy with another application (like playing a track in fb2k).
Try it and let me know if you experience the same thing.
The "Do not use audio features..." is where it really gets interesting. It basically removes the device logically from your system. It becomes invisible to applications that can't/don't use ASIO or KS. In effect it does not load windows mixer or the soundcard mixer/panel, thereby eliminating the volume control and other possible processing by the mixer completely from the path. Whether this is of any advantage or not, I am not sure. Because ASIO or KS also essentially bypass the kmixer but not the soundcard's mixer, right ? Well, even with ASIO or KS the windows or soundcard mixer's volume control is still very much in control! And I believe its a well accepted fact that any type of 'digital' volume control is not desirable.So my theory is that even if you use ASIO or KS, you should always check the "Do not use audio feature of the device". Ofcourse you will loose sound from all other applications that cant do KS or ASIO (virtually everything).
PM:First off, I am not sure why you have a windows volume control working if using ASIO or KS. Just don't select any device that you are using (say, for example, use an onboard codec) as the Windows Default Playback device.
With most ASIO soundcards, you get a DSP mixing suite. This means there IS a level control for the device, but it's NOT the kmixer, it doesn't resample, and if set to "100%" or "0db" it's not altering the data in any way. The only trouble with digital volume controls is that the effective dynamic range decreases as you decrease volume.
PM: "So my theory is that even if you use ASIO or KS, you should always check the "Do not use audio feature of the device".
I'm thinking this won't work in all cases - I just proved it does work when using ASIO and the Creative X-fi.
I will try this with the M-Audio Revo (which also has an ASIO driver) and see if it does the same thing. When you disable "audio features" on the device, you also disable "mixer" and "midi" features of the device which may be required to use ASIO.
The crux of the above is that an ASIO based DSP mixer is not one in the same with the Kmixer.
Here's one more observation that I am having a tough time understanding -I have a soundcard installed and working properly, but I do not have any devices listed in the "Sounds and Audio Devices", obviously
because I have selected "Do not use audio features" for that device/soundcard. So there is no Window's or the soundcard's mixer/panel available, and any application like WMP, Messenger, windows sounds etc. cannot see this device and wont play.
All that is fine and as expected.However, fb2k can play just fine via DirectSound. I was expecting it to play KS but not DS. At this point how is KS different (or better) than DS ? Is the flow of data through the layers (mixers, drivers) any different between KS and DS, in this situation ?
Hi,I see this is a rather old thread, but a while back I tried to sort this stuff out and found, like you guys have, that it's a bloody morass. Gleaning what I could from the stuff on MSDN I think part of the confusion is that each device can set up the virtual signal paths ("exposed pins") differently, and pick and choose what functions it wants to handle and which are left to Windows. So it's likely a whole new game for each device. Bottom line, I finally gave up all hope of really understanding it.
Like you I found that one of the "devices" I was playing with, I think it was the on-board Realtek chip and driver, seemed to support DX10 as a native format so that it could be accessed directly when not mapped through the Windows audio stack. As far as sound quality, DX seemed fine to me. I also played with ASIO but not KS.
Good luck. Please pass on what you learn...
Dammit PM!You're asking REALLY good questions here! lol
AGAIN I thought I knew this one too. I was under the impression that to get away from the windows audio stack and bypass the kmixer you needed to use either:
a) ASIO output plugin to ASIO driver (ASIO)
b) ASIO output plugin to ASIO4ALL (actually kernel streaming)
c) Kernel streaming output plugin (kernel streaming)As for Waveout and DirectSound? I thought BOTH used Kmixer.
Perhaps others can chime in here. Most folks around here use either kernel streaming, ASIO or a USB output.
USB outputs vary quite a bit. This depends on whether they use the windows driver (usbaudio.sys) or a custom driver. If it's a custom driver, what exactly it's doing can vary quite a bit.
Now, if you are using directsound, and you can pass a DTS track through (with volume at 100% - no higher or lower) and your receiver auto-detects the DTS format, then SURE... the file has not been munched by Kmixer. This would be a great test.
You'd be surprised how much of what is "common knowlege" gets quickly debunked from time to time. The rumor-mill and "forum knowlege" in PC Audio is deadly. Not out of malice or anything... it's just that a lot of this stuff is very poorly documented (if at all) or reads like a NASA white paper, or is simply very counter intuitive.
That's why your questions are excellent ones.
This post is made possible by the generous support of people like you and our sponsors: