IPB

Welcome Guest ( Log In | Register )

> foobar2000 General Forum Rules

This is NOT a tech support forum.
Tech support questions go to foobar2000 Tech Support forum instead.

See also: Hydrogenaudio Terms of Service.

 
Reply to this topicStart new topic
Realtek ALC850 kernel streaming?
Fryguy
post Apr 11 2006, 02:02
Post #1





Group: Members
Posts: 12
Joined: 22-November 05
Member No.: 25922



Has anyone gotten realtek alc850 (onboard sound on lots of athlon64 nforce3/4 boards) working with foobar? I'm using digital output to a receiver, so I dont' really have any reason to spend the money on the soundcard since it's just passing a digital stream and not really touching it, but I'd like to get kernel streaming working.

Any ideas?
Go to the top of the page
+Quote Post
Duble0Syx
post Apr 11 2006, 03:33
Post #2





Group: Members
Posts: 465
Joined: 2-May 04
Member No.: 13847



QUOTE (Fryguy @ Apr 10 2006, 05:02 PM) *
Has anyone gotten realtek alc850 (onboard sound on lots of athlon64 nforce3/4 boards) working with foobar? I'm using digital output to a receiver, so I dont' really have any reason to spend the money on the soundcard since it's just passing a digital stream and not really touching it, but I'd like to get kernel streaming working.

Any ideas?

I have a Realtek ALC655 chip as my onboard chip on one box. I use the spdif out on it as well. It only supports 48kHz digital out, and after reading the specs, yours does too. Which means it will be resampling the audio prior to sending it to the receiver. There is no way around this as far as I know. I use kernel streaming output regardless though, why not? I did not have to have any special settings in order to use it either. It's stable and it makes me feel better even it doesn't have any noticeable effect on the sound.
http://www.realtek.com.tw/products/product...modelid=2003101
If you want cheap, bit-accurate digital out, get a Chaintech AV-710. Optical out only on that card though, so unless the 3' toslink cable is long enough, I hope your rich enough to buy a longer one or get an optical to coax converter. smile.gif
Go to the top of the page
+Quote Post
Fryguy
post Apr 11 2006, 03:37
Post #3





Group: Members
Posts: 12
Joined: 22-November 05
Member No.: 25922



QUOTE (Duble0Syx @ Apr 10 2006, 10:33 PM) *
QUOTE (Fryguy @ Apr 10 2006, 05:02 PM) *

Has anyone gotten realtek alc850 (onboard sound on lots of athlon64 nforce3/4 boards) working with foobar? I'm using digital output to a receiver, so I dont' really have any reason to spend the money on the soundcard since it's just passing a digital stream and not really touching it, but I'd like to get kernel streaming working.

Any ideas?

I have a Realtek ALC655 chip as my onboard chip on one box. I use the spdif out on it as well. It only supports 48kHz digital out, and after reading the specs, yours does too. Which means it will be resampling the audio prior to sending it to the receiver. There is no way around this as far as I know. I use kernel streaming output regardless though, why not? I did not have to have any special settings in order to use it either. It's stable and it makes me feel better even it doesn't have any noticeable effect on the sound.
http://www.realtek.com.tw/products/product...modelid=2003101
If you want cheap, bit-accurate digital out, get a Chaintech AV-710. Optical out only on that card though, so unless the 3' toslink cable is long enough, I hope your rich enough to buy a longer one or get an optical to coax converter. smile.gif


What is the chaintech card going to do for me that my realtek doesn't already do?

Edit: also I just tried ks for the first time since upgrading to 0.9, and it still doesn't work. I have to drop down to 16bit, and then it actually opens the device, but there is no output, it's completely silent. Is there a volume setting or something that I am missing?

This post has been edited by Fryguy: Apr 11 2006, 03:50
Go to the top of the page
+Quote Post
TrNSZ
post Apr 13 2006, 04:49
Post #4





Group: Developer
Posts: 717
Joined: 25-September 01
From: ... The Studio
Member No.: 20



Why are you using Kernel Streaming output anyway?

If you do not have a good reason to do so, you should not be using it. If you think it sounds different or produces different output in any way, you have been incredibly misinformed.

RealTek describes that chip as "a 16-bit, full-duplex AC'97 ... audio codec". If you were using any bitdepth other than 16-bit before, chances are the driver was just truncating the extra bits, leaving you with 16-bit audio anyway -- except it was being dithered. This could, in theory, reduce quality. RealTek further describes this chip as having a "48KHz sampling rate". If you are using KS and you aren't using the Resampler component configured for 48khz, you're just piling on one user error after another.

KS on top would be merely adding to your placebo effect. I hear the effects of placebo are additive. *sarcasm* Please do yourself a favor and actually read the warning that KS pops up. You have absolutely no reason to use KS whatsoever with your setup. The problem here is between the keyboard and the chair.

This post has been edited by TrNSZ: Apr 13 2006, 04:52
Go to the top of the page
+Quote Post
Fryguy
post Apr 13 2006, 05:01
Post #5





Group: Members
Posts: 12
Joined: 22-November 05
Member No.: 25922



QUOTE (TrNSZ @ Apr 12 2006, 11:49 PM) *
Why are you using Kernel Streaming output anyway?

If you do not have a good reason to do so, you should not be using it. If you think it sounds different or produces different output in any way, you have been incredibly misinformed.

RealTek describes that chip as "a 16-bit, full-duplex AC'97 ... audio codec". If you were using any bitdepth other than 16-bit before, chances are the driver was just truncating the extra bits, leaving you with 16-bit audio anyway -- except it was being dithered. This could, in theory, reduce quality. RealTek further describes this chip as having a "48KHz sampling rate". If you are using KS and you aren't using the Resampler component configured for 48khz, you're just piling on one user error after another.

KS on top would be merely adding to your placebo effect. I hear the effects of placebo are additive. *sarcasm* Please do yourself a favor and actually read the warning that KS pops up. You have absolutely no reason to use KS whatsoever with your setup. The problem here is between the keyboard and the chair.


Wow, appreciate the flame. I more or less wanted to use kernel streaming to experiment. I realize it's going to have 0 effect on sound quality, just wanted to more or less play around. I more or less want to get it to work "just because."
Go to the top of the page
+Quote Post
Duble0Syx
post Apr 13 2006, 06:02
Post #6





Group: Members
Posts: 465
Joined: 2-May 04
Member No.: 13847



QUOTE (Fryguy @ Apr 12 2006, 08:01 PM) *
QUOTE (TrNSZ @ Apr 12 2006, 11:49 PM) *

Why are you using Kernel Streaming output anyway?

If you do not have a good reason to do so, you should not be using it. If you think it sounds different or produces different output in any way, you have been incredibly misinformed.

RealTek describes that chip as "a 16-bit, full-duplex AC'97 ... audio codec". If you were using any bitdepth other than 16-bit before, chances are the driver was just truncating the extra bits, leaving you with 16-bit audio anyway -- except it was being dithered. This could, in theory, reduce quality. RealTek further describes this chip as having a "48KHz sampling rate". If you are using KS and you aren't using the Resampler component configured for 48khz, you're just piling on one user error after another.

KS on top would be merely adding to your placebo effect. I hear the effects of placebo are additive. *sarcasm* Please do yourself a favor and actually read the warning that KS pops up. You have absolutely no reason to use KS whatsoever with your setup. The problem here is between the keyboard and the chair.


Wow, appreciate the flame. I more or less wanted to use kernel streaming to experiment. I realize it's going to have 0 effect on sound quality, just wanted to more or less play around. I more or less want to get it to work "just because."

What I was saying was simply. You won't get bit-perfect digital output from the Realtek onboard audio. I only pointed out the Chaintech card because it's the cheapest card out there that can give you bit-perfect digital out. You won't likely hear the difference between it or your onboard audio. The only soundcards I've ever been able to ABX are the onboard Realtek chip on my new board and the Sound Blaster 16 ISA card I was using before.
I get sound from the onboard SPDIF output from my Realtek ALC655. Just made a simple connector for a coax cable since I'm too poor for a toslink. Plugged it in, hit play and out came the tunes. I recommned using DirectSound simply because it works and as stated, kernel streaming serves no real purpose. There was some reason I used kernel streaming originally that I've long since forgotten and was probably not true anyway. Get updated drivers, make sure the SPDIF output is turned on in the little realtek control panel and make sure the right sound device is selected in foobars output settings and you should get sound. Not bit-perfect, but I doubt you'll notice. Only thing you may notice, if you've got great ears, is some improvement over the analog outputs. I haven't actually checked though.
Go to the top of the page
+Quote Post
chacallot
post Apr 18 2006, 21:11
Post #7





Group: Members
Posts: 5
Joined: 18-April 06
Member No.: 29730



Hi!

Yes, you can do it, as I did!

Just selected Kernel Streaming as desired output method in Foobar 2000 v0.8.3 though.
So am not sure that will help you.

He're some details about my conf :
Windows XP pro SP2 with latest patches available.
Asus A8N-E MB, with some Athlon 64 something. This MB includes a ALC850 thingie whose drivers are 5.10.0.5870.

Only thing I see that could go wrong is if you chose 24bit output data format in Foobar preference/playback.
As it only works with 16 or 32bits for this param (for me). Else I get a Foobar error msg about KS module.


Despite what those flamers answered you before there is a way to pass-through bits to the SPDIF output as for example the AC3/DTS codec is able to do it.
The proof of that is that my receivers shows the 7 channels activated while playing such a AC3/DTS encoded Divx.
This can only be achieved cause this codec is able to 'passthrough' through the SPDIF and if this codec can, others too..

But maybe the rite way to achieve this is not using KernelStreaming output but some SPDIF passthrough output, and I have not found which player can do that yet...
And some know about that, I'd be glad they share their knowledge!

Rgds,
Chacallot.
Go to the top of the page
+Quote Post
TrNSZ
post Apr 19 2006, 05:12
Post #8





Group: Developer
Posts: 717
Joined: 25-September 01
From: ... The Studio
Member No.: 20



QUOTE (chacallot @ Apr 18 2006, 04:11 PM) *
Despite what those flamers answered you before there is a way to pass-through bits to the SPDIF output as for example the AC3/DTS codec is able to do it.
The proof of that is that my receivers shows the 7 channels activated while playing such a AC3/DTS encoded Divx.
This can only be achieved cause this codec is able to 'passthrough' through the SPDIF and if this codec can, others too..


This is pure misinformation. I never said you cannot pass-through bits to SPDIF unmodified. I said that if you think you MUST bypass kmixer to do so, you are misinformed. If you think that you have to use Kernel Streaming, you are misinformed. If you think that bypassing kmixer and using kernel streaming will magically ensure bit-perfect output, are are also informed. If kmixer is "mangling" you data and you feel that it will "sound better" by going to lengths to bypass it, you are (in 99 out of 100 cases) just plain wrong.

For some details, I'd recommend that you look at this thread which claims to explain some internals about kmixer, but be sure to follow this up by completely reading this thread as well. It's somewhat long and confusing, so read it completely.

The real truth is that kmixer may or may not "mangle" your output. It is a function of using proper drivers for you card. Bit-perfect output is absolutely achievable with DirectSound with the correct drivers and an audio board that will support such. Kmixer is not a real-life for 99% of the time. It certainly DOES NOT SOUND ANY DIFFERENT. If you think it does, I beg you to prove us wrong with proper testing. If you feel you need such bit-perfect playback, I'd recommend that you complain to manufacturer of your sound card -- however, chances are that they won't care, and for this reason:

This "mangling" that can be measured is negligable. Any distortion introduced here will not be audible You can look at KikeG's testing from back in 2003.

Let's just say that if, when you listen to music you get annoying by the sound of your hair growing, or at a heavy metal show, the sound of the guy breathing next to you stops you from enjoying the show, then you might benefit from such nonsense.

I don't know if bit-perfect output would be possible at 44.1khz with your particular setup, but it is not impossible, and kmixer is not the source of your problems. Everyone worries about kmixer; be more concerned with the card and the drivers you use. The only possible use I can think of that any consumer would need to absolute bit-perfect passthrough via a system clearly designed to playback multiple PCM streams would be the use of an off-board DTS decoder.

I want it made clear to everyone that while KS is not useless, the only tasks it can help you with are specialized. Requirements for high-quality playback are different than requirements for high-quality studio recording and mixing. You don't need the low-latency or whatever other benefits it could provide in an audio player. Unless you actually have some DTSWAV/DDWAV files or other random data that you feel you must absolutely push down your SPDIF, you are wasting your time.

I think that it should be a prerequisite to explain why you want to do something along with posting the question asking how. Most people have no idea what kernel streaming does, why it would be needed, and how to set it up properly.

QUOTE
Wow, appreciate the flame. I more or less wanted to use kernel streaming to experiment. I realize it's going to have 0 effect on sound quality, just wanted to more or less play around. I more or less want to get it to work "just because."

So you are not only wasting your time, you are wasting ours as well? You could have searched here, or searched on the web, and found all the answers to your questions.

This post has been edited by TrNSZ: Apr 19 2006, 05:20
Go to the top of the page
+Quote Post
david_dl
post Apr 19 2006, 05:30
Post #9





Group: Members
Posts: 604
Joined: 17-December 05
From: New Zealand
Member No.: 26461



Fine, it doesn't sound any different. But it DOES change the data, ever so slightly, and for PCM data, that isn't a problem. HOWEVER, AFAIK some surround encodings (ie. DTS/AC3) work by sending non PCM data through the system to the digital output, where a receiver can correctly interpret it as compressed surround sound. Because it is not PCM data, and kmixer cannot know that, the ever-so-slight modification it makes completely corrupts the data stream and prevents the whole thing working.
Go to the top of the page
+Quote Post
TrNSZ
post Apr 19 2006, 06:03
Post #10





Group: Developer
Posts: 717
Joined: 25-September 01
From: ... The Studio
Member No.: 20



QUOTE (david_dl @ Apr 19 2006, 12:30 AM) *
Fine, it doesn't sound any different. But it DOES change the data, ever so slightly, and for PCM data, that isn't a problem. HOWEVER, AFAIK some surround encodings (ie. DTS/AC3) work by sending non PCM data through the system to the digital output, where a receiver can correctly interpret it as compressed surround sound. Because it is not PCM data, and kmixer cannot know that, the ever-so-slight modification it makes completely corrupts the data stream and prevents the whole thing working.

You obviously did not read a single word I wrote, and if you did, you failed to comprehend the details. Either go back and actually read the thread before responding, or if you read it, read it again.

I made this case very clear already, but I should also stress that any differences in the output may or may not be the result of kmixer, and spreading blatant misinformation (that kmixer will change your output) does no one any good.

It may or may not change your output, depending on many factors, including the hardware and the drivers. Edit: I have personally witnessed DirectSound working to stream DTS to my external DAC. I've done it on many setups. I've seen it with waveout and with kernel streaming and ASIO too. The simple fact here is, that for a variety of reasons, KS is usually NOT the appropriate solution here and it's unsupported for a reason.

You could easily search and find threads from 2003 and earlier that discuss these things in depth.

At this point I give up.

I'm not going to sit around here and post the same things over and over again if no one is capable of reading or using the search function.

This post has been edited by TrNSZ: Apr 19 2006, 06:07
Go to the top of the page
+Quote Post
chacallot
post Apr 19 2006, 21:38
Post #11





Group: Members
Posts: 5
Joined: 18-April 06
Member No.: 29730



QUOTE
You obviously did not read a single word I wrote, and if you did, you failed to comprehend the details. Either go back and actually read the thread before responding, or if you read it, read it again.

I made this case very clear already, but I should also stress that any differences in the output may or may not be the result of kmixer, and spreading blatant misinformation (that kmixer will change your output) does no one any good.

It may or may not change your output, depending on many factors, including the hardware and the drivers. Edit: I have personally witnessed DirectSound working to stream DTS to my external DAC. I've done it on many setups. I've seen it with waveout and with kernel streaming and ASIO too. The simple fact here is, that for a variety of reasons, KS is usually NOT the appropriate solution here and it's unsupported for a reason.

You could easily search and find threads from 2003 and earlier that discuss these things in depth.

At this point I give up.

I'm not going to sit around here and post the same things over and over again if no one is capable of reading or using the search function.


Yes, give up man.
You're really aggressive and never answered the question asked.

Some guys wants to try to use kernel streaming with his hardware. That was the question.
You have no idea why it doesnt work. And you just post your *sarcasm* and tell him that his problem is between him and his keyboard...

Your answers are not olny aggressive but also vague, useless... Bizarre... What's the point of :
QUOTE
Let's just say that if, when you listen to music you get annoying by the sound of your hair growing, or at a heavy metal show, the sound of the guy breathing next to you stops you from enjoying the show, then you might benefit from such nonsense.


Pretty useless info... But if what you like is reading your prose, enjoy...

Rgds,
Chacallot.
Go to the top of the page
+Quote Post
Duble0Syx
post Apr 19 2006, 22:15
Post #12





Group: Members
Posts: 465
Joined: 2-May 04
Member No.: 13847



QUOTE (chacallot @ Apr 19 2006, 12:38 PM) *
Yes, give up man.
You're really aggressive and never answered the question asked.

Some guys wants to try to use kernel streaming with his hardware. That was the question.
You have no idea why it doesnt work. And you just post your *sarcasm* and tell him that his problem is between him and his keyboard...

Your answers are not olny aggressive but also vague, useless... Bizarre... What's the point of :
QUOTE

Let's just say that if, when you listen to music you get annoying by the sound of your hair growing, or at a heavy metal show, the sound of the guy breathing next to you stops you from enjoying the show, then you might benefit from such nonsense.


Pretty useless info... But if what you like is reading your prose, enjoy...

Rgds,
Chacallot.

I thought I had answered his question. The Realtek chips resample the PCM output in the hardware. Unless someone find a way of bypassing that you cannot get bitperfect audio from the spdif. Unless your listening 16-bit 48kHz audio. I get sound just fine from the spdif on my realtek chip. It's just resampled. I'd rather it be bitperfect, but I can deal with it knowing I'll never hear the difference. DirectSound is doing fine, Kernel Streaming sounds identical. So if you want bitperfect, your out of luck with onboard realtek chips.

This post has been edited by Duble0Syx: Apr 19 2006, 22:16
Go to the top of the page
+Quote Post
saratoga
post Apr 19 2006, 22:22
Post #13





Group: Members
Posts: 4847
Joined: 2-September 02
Member No.: 3264



QUOTE (chacallot @ Apr 19 2006, 01:38 PM) *
QUOTE

You obviously did not read a single word I wrote, and if you did, you failed to comprehend the details. Either go back and actually read the thread before responding, or if you read it, read it again.

I made this case very clear already, but I should also stress that any differences in the output may or may not be the result of kmixer, and spreading blatant misinformation (that kmixer will change your output) does no one any good.

It may or may not change your output, depending on many factors, including the hardware and the drivers. Edit: I have personally witnessed DirectSound working to stream DTS to my external DAC. I've done it on many setups. I've seen it with waveout and with kernel streaming and ASIO too. The simple fact here is, that for a variety of reasons, KS is usually NOT the appropriate solution here and it's unsupported for a reason.

You could easily search and find threads from 2003 and earlier that discuss these things in depth.

At this point I give up.

I'm not going to sit around here and post the same things over and over again if no one is capable of reading or using the search function.


Yes, give up man.
You're really aggressive and never answered the question asked.

Some guys wants to try to use kernel streaming with his hardware. That was the question.
You have no idea why it doesnt work. And you just post your *sarcasm* and tell him that his problem is between him and his keyboard...




All the stuff you quoted was just him correcting your post, so of course it doesn't say anything about the first post.
Go to the top of the page
+Quote Post
chacallot
post Apr 19 2006, 22:42
Post #14





Group: Members
Posts: 5
Joined: 18-April 06
Member No.: 29730



QUOTE
All the stuff you quoted was just him correcting your post, so of course it doesn't say anything about the first post.


You're as wrong as your friend.
Read again my unique post before the one you just replied to.

I answered the question :
Yes you can use kernel streaming output with a ALC850. And I gave specific, eventually usefull info.
I added that you could passthrough bits through the SPDIF output (that TrNSZ aggrees with or doesnt know better than me...).
And I also implied that TrNSZ was flaming, which cant be denied either provided this in his first answer : "the problem is between you and your keybord".

Hope, you can understand this shorter version.

Rgds,
Chacallot.
Go to the top of the page
+Quote Post
chacallot
post Apr 19 2006, 22:54
Post #15





Group: Members
Posts: 5
Joined: 18-April 06
Member No.: 29730



QUOTE (Duble0Syx @ Apr 19 2006, 03:15 PM) *
QUOTE (chacallot @ Apr 19 2006, 12:38 PM) *

Yes, give up man.
You're really aggressive and never answered the question asked.

Some guys wants to try to use kernel streaming with his hardware. That was the question.
You have no idea why it doesnt work. And you just post your *sarcasm* and tell him that his problem is between him and his keyboard...

Your answers are not olny aggressive but also vague, useless... Bizarre... What's the point of :
QUOTE

Let's just say that if, when you listen to music you get annoying by the sound of your hair growing, or at a heavy metal show, the sound of the guy breathing next to you stops you from enjoying the show, then you might benefit from such nonsense.


Pretty useless info... But if what you like is reading your prose, enjoy...

Rgds,
Chacallot.

I thought I had answered his question. The Realtek chips resample the PCM output in the hardware. Unless someone find a way of bypassing that you cannot get bitperfect audio from the spdif. Unless your listening 16-bit 48kHz audio. I get sound just fine from the spdif on my realtek chip. It's just resampled. I'd rather it be bitperfect, but I can deal with it knowing I'll never hear the difference. DirectSound is doing fine, Kernel Streaming sounds identical. So if you want bitperfect, your out of luck with onboard realtek chips.



Hey but which question man?
I asked no question in the post you quoted!

But your rite, someone already said that.
And I repeat that the AC3/DTS codec is able to passthrough the SPDIF of ALC850.

Rgds,
Chacallot.
Go to the top of the page
+Quote Post
deoch
post Apr 20 2006, 03:03
Post #16





Group: Members
Posts: 8
Joined: 25-October 04
Member No.: 17820



QUOTE (Fryguy @ Apr 10 2006, 06:02 PM) *
Has anyone gotten realtek alc850 (onboard sound on lots of athlon64 nforce3/4 boards) working with foobar? I'm using digital output to a receiver, so I dont' really have any reason to spend the money on the soundcard since it's just passing a digital stream and not really touching it, but I'd like to get kernel streaming working.

Any ideas?


Have you tried the new v0.9.1 beta with new Kernel Streaming component?
http://www.foobar2000.org/beta/components.html
Go to the top of the page
+Quote Post
Fryguy
post Apr 20 2006, 03:30
Post #17





Group: Members
Posts: 12
Joined: 22-November 05
Member No.: 25922



QUOTE (chacallot @ Apr 19 2006, 05:54 PM) *
QUOTE (Duble0Syx @ Apr 19 2006, 03:15 PM) *

QUOTE (chacallot @ Apr 19 2006, 12:38 PM) *

Yes, give up man.
You're really aggressive and never answered the question asked.

Some guys wants to try to use kernel streaming with his hardware. That was the question.
You have no idea why it doesnt work. And you just post your *sarcasm* and tell him that his problem is between him and his keyboard...

Your answers are not olny aggressive but also vague, useless... Bizarre... What's the point of :
QUOTE

Let's just say that if, when you listen to music you get annoying by the sound of your hair growing, or at a heavy metal show, the sound of the guy breathing next to you stops you from enjoying the show, then you might benefit from such nonsense.


Pretty useless info... But if what you like is reading your prose, enjoy...

Rgds,
Chacallot.

I thought I had answered his question. The Realtek chips resample the PCM output in the hardware. Unless someone find a way of bypassing that you cannot get bitperfect audio from the spdif. Unless your listening 16-bit 48kHz audio. I get sound just fine from the spdif on my realtek chip. It's just resampled. I'd rather it be bitperfect, but I can deal with it knowing I'll never hear the difference. DirectSound is doing fine, Kernel Streaming sounds identical. So if you want bitperfect, your out of luck with onboard realtek chips.



Hey but which question man?
I asked no question in the post you quoted!

But your rite, someone already said that.
And I repeat that the AC3/DTS codec is able to passthrough the SPDIF of ALC850.

Rgds,
Chacallot.



For those in this thread who care, I went and found updated drives for my alc850 (dated april 13), and that enabled kernel streaming. I was using drivers that were about a year old, and for some reason weren't supporting kernel streaming. Now to mess around with spdif settings.

Thanks a lot for the help guys, those of you that provided it.
Go to the top of the page
+Quote Post
Martin H
post May 1 2006, 03:02
Post #18





Group: Members
Posts: 857
Joined: 5-March 05
From: Denmark
Member No.: 20365



QUOTE (TrNSZ @ Apr 19 2006, 06:12 AM) *
I don't know if bit-perfect output would be possible at 44.1khz with your particular setup, but it is not impossible,

Some posts later in that thread you linked to, then KikeG said :

QUOTE
Well, a couple of months ago I managed to get mi CMI8738 based card digital input to work.

Using it, and bit-perfect recording the digital output of my Audiophile card at 44.1 KHz mode, I've been able to verify that kmixer indeed does something to the data passed to it. The change is very subtle, so it was not detectable on my analog measurements of the soundcard output. What I've verified that kmixer does to 16-bit audio data, is just mangle the last bit of the data. It does like some kind of re-dithering of the signal, adding a very little amount of spectrally uniform noise to the signal, so that it is no longer bit-perfect. It also adds a very little amount (around -120 dB amplitude) of distortion that can be considered negligible."

Note that when kmixer is acting and you play 44.1 KHz data, it can do do two different things depending on the driver implementation. The first is just this relatively bening bit mangling I've talked about in this post. But on some cards and modes (wave output instead of directsound, for example), it will resample the signal to 48 KHz, and this is a greater change to the signal. I haven't done very detailed tests over this resampling, but it worsens a little bit more the SNR of the signal, causes some low-level distortion and causes a very slight HF rollof. At first I don't think this is audible under usual listening conditions, but I haven't done any listening tests.

Note also that there are some professional-oriented cards that use special WDM drivers that don't suffer from any of those kmixer issues. These drivers don't fully conform to the WDM standard, and can't use kernel streaming, but, on the other side, they don't need it. RME cards for example, use this kind of non-standard, kmixer-free, WDM drivers.


Source : http://www.hydrogenaudio.org/forums/index....ndpost&p=109854
Go to the top of the page
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 24th July 2014 - 10:47