IPB

Welcome Guest ( Log In | Register )

My tests over kmixer effects, Seem to be none...
KikeG
post Jan 16 2003, 09:40
Post #1


WinABX developer


Group: Developer
Posts: 1578
Joined: 1-October 01
Member No.: 137



I've been doing some tests over kmixer effect, both using standard waveout and directsound, connecting my TBSC digital output to my Audiophile digital input, under WinXP (no SP1), and I'm sure that with a single stream at 48 KHz, with the TBSC mixer volume at max, the kmixer doesn't touch a bit of the audio stream, it's sent bit-perfectly to the output of the card. At 44.1 KHz I can't be so conclusive, since the TBSC resamples everything to 48 KHz and I've had some problems to test it the same way, but according to my analog measurements in loopback mode of Audiophile output, there is no trace of signal degradation over the 44.1 KHz played data.

...So it's very possible that this kmixer sounding worse than ASIO or k.streaming is our old friend mr. placebo entering into scene again. wink.gif

Anyway, I'll do some more tests in the future.

This post has been edited by KikeG: Jan 16 2003, 09:42
Go to the top of the page
+Quote Post
 
Start new topic
Replies
KikeG
post Aug 1 2003, 17:55
Post #2


WinABX developer


Group: Developer
Posts: 1578
Joined: 1-October 01
Member No.: 137



Well, I just did a few more tests. I own now both a Revo and an Audiophile, so I can play all types of data on the digital output of the Revo and record them with the digital input of the Audiophile. I just did some RMAA 4.3 measurements, that uses WDM (directsound) drivers, and here are the results:

I will give results without A weighting, I like it better.

1st figure is reference, best possible value. 2nd is kmixer bit-mangled output.

Frequency response is totally flat in all cases, so is omitted.

16 bit, 44.1 KHz:
============
Noise: -96.4 dB, -93.4 dB
Dynamic range: 94 dB, 90.9 dB
THD: 0.000%, 0.001%
THD+N: 0.003%, 0.004%
IMD+Noise: 0.006%, 0.008%
Crosstalk @1KHz: -94 dB, -90 dB

The distortion product that appears at the THD measurement is at -110 dB, not -120 as I said previously. It is still a negligible value in my opinion. The biggest difference is the slight increase of the noise floor. As you see, even here the difference is quite small.

24 bit, 44.1 KHz:
============
Noise: -146.3 dB, -141.5 dB
Dynamic range: 139.5 dB, 137.3 dB
THD: 0.000%, 0.000%
THD+N: 0.000%, 0.000%
IMD+Noise: 0.000%, 0.000%
Crosstalk @1KHz: -141.8dB, -137.2 dB

For 32-bit audio, results are slightly better but very similar.

Taking into account that due to real-world constraints of electronics the best hardware available can't have a dynamic range better than around 120 dB, the effect of kmixer bit-mangling in this case is totally negligible.

And, if you play your 16-bit data as 24 bit or 32 bit, the result is that in practice the full 16-bit resolution is retained, even if you don't use kernel streaming, because the bit-mangling effects are much below 16-bit resolution. In a RMAA measurement, the results in this case were identical to the 16-bit reference results. But this will be true just if your card is a true 24-bit card.

Even when the differences are small or very small and quite possibly inaudible even in the the worst case, this bit-mangling will prevent from bit-perfect digital transfers in any case.

Again, note that this measurements are about this kmixer bit-mangling, which I don't think is any kind of resampling. Measurements of real kmixer resampling (that happens at my card when for example both a stream at 48 KHz and 44.1 KHz are played at same time, or when the output is locked at 48 KHz and you play a 44.1 KHz stream), and its effects are much more evident, see link at a previous post. Resampling produces a worse THD & IMD, easy to see at the THD spectrum, and a slight but measurable difference in frequency response. The effects measured here are just due to some kind of partial "re-dithering" of the signal, probably performed at some stage of kmixer software mixing. But it's not resampling.

As I said at a previous post, on some cards (not Revo) resampling will happen whenever you play a 44.1 KHz stream, or when you use waveout instead of directsound... it depends on the card and its drivers, but in better cards this resampling happens just when it's unavoidable (simultaneous playback of both a 48 and 44.1 stream, or lock of the sampling rate at 48 KHz).

So, the bit-mangling measured here, always, always happens when you play 44.1 KHz data on WinXP (and same seems to happen with Win2K), which is something that AFAIK Microsoft doesn't say. It can be avoided just if you use kernel streaming or ASIO audio interfaces, or your card supports hardware mixing (same as directsound acceleration) and it is enabled.

Note that Creative cards support hardware mixing and kernel streaming, but they internally resample all 44.1 KHz data, so in practice the result is probably even worse that if they use kmixer resampling.

This post has been edited by KikeG: Aug 1 2003, 17:59
Go to the top of the page
+Quote Post

Posts in this topic
- KikeG   My tests over kmixer effects   Jan 16 2003, 09:40
- - thomaspf   Could you describe this setup in a bit more detail...   Jan 16 2003, 20:02
- - KikeG   I used WinXP pre-SP1. As I said, at 48 KHz, I use...   Jan 17 2003, 09:46
- - kaiwei   Did anyone actually claimed that it sounds better?...   Jan 17 2003, 11:52
- - KikeG   I don't think anybody has claimed it sounds be...   Jan 17 2003, 12:06
- - dev0   So basically all of thomaspf claims turn out to be...   Jan 17 2003, 16:17
- - thomaspf   Very interesting. All the experiments I did came a...   Jan 17 2003, 17:17
- - Pio2001   Loopbacking a soundcard into itself can lead to pr...   Jan 17 2003, 18:43
- - thomaspf   Interesting. I thought input and output of this ca...   Jan 17 2003, 19:21
- - KikeG   thomaspf, there's one thing I don't unders...   Jan 18 2003, 17:59
- - thomaspf   Strange. I have an M-audio DIO24/96 and I have no ...   Jan 19 2003, 06:11
- - Pio2001   Actually, long ago, I managed the same loopback wi...   Jan 19 2003, 14:51
- - thomaspf   Windows has supported a various driver models over...   Jan 19 2003, 18:03
- - thomaspf   A few more results. First I recreated this little ...   Jan 20 2003, 08:42
- - KikeG   I have only one computer too, but two soundcards i...   Jan 20 2003, 13:00
- - KikeG   So, all software that uses waveout (WinABX, abc/hr...   Jan 20 2003, 13:03
- - KikeG   thomaspf, make sure that in the settings of the pa...   Jan 20 2003, 14:50
- - thomaspf   Looks like we are getting on the same page here...   Jan 20 2003, 18:32
- - KikeG   In my Winamp 2 directsound plugin, I have no optio...   Jan 21 2003, 10:15
- - thomaspf   My DAC/surround sound proc is on it's way back...   Jan 21 2003, 21:58
- - KikeG   Ok, I've managed to get decent drivers for my ...   Jan 24 2003, 17:14
- - Continuum   QUOTE (KikeG @ Jan 24 2003 - 05:14 PM)Ok, I...   Jan 24 2003, 17:41
- - thomaspf   @kikeG I am expecting to get my DAC back this we...   Jan 25 2003, 00:31
- - KikeG   QUOTE (Continuum @ Jan 24 2003 - 05:41 PM)I h...   Jan 26 2003, 14:38
- - KikeG   Player: Winamp 2.81 Drivers: latest M-Audio Dio24...   Jan 26 2003, 14:41
- - thomaspf   I finally got my DAC back and repeated my tests vi...   Jan 29 2003, 08:46
- - Continuum   Are you sure that all volume levels are set to max...   Jan 29 2003, 11:53
- - KikeG   Yes, that could happen, but depends also on the se...   Jan 29 2003, 14:38
- - thomaspf   I set everything up as it shoud and also consulted...   Jan 29 2003, 19:07
- - thomaspf   Here is another tidbit. I had a conversation with ...   Feb 3 2003, 00:09
- - KikeG   This is strange, I hope I had a DTS decoder to mak...   Feb 3 2003, 09:25
- - Pio2001   I get bit perfect digital playback-record in loopb...   Feb 9 2003, 07:26
- - KikeG   I think the relevant results here would be for 44....   Feb 9 2003, 20:16
- - thomaspf   I just checked the Marian WEB site. It looks like ...   Feb 9 2003, 21:10
- - KikeG   OK, I've performed several RMAA (RightMark Aud...   Mar 6 2003, 16:35
- - KikeG   Well, a couple of months ago I managed to get mi C...   Jun 30 2003, 13:03
- - KikeG   Well, I just did a few more tests. I own now both ...   Aug 1 2003, 17:55
- - balazer   I understand that you need to use something like A...   Aug 19 2003, 10:02
- - KikeG   I already answered at the AVS thread. I did all my...   Aug 19 2003, 18:29
- - Patsoe   QUOTE (KikeG @ Jun 30 2003, 01:03 PM)There...   Aug 22 2003, 00:13
- - Peter   I suppose they just perform mixing/resampling at h...   Aug 22 2003, 01:10
- - AstralStorm   It depends on the card and its drivers. TerraTec A...   Aug 22 2003, 01:15
- - Patsoe   QUOTE (zZzZzZz @ Aug 22 2003, 01:10 AM)(ABX a...   Aug 22 2003, 01:22
- - Peter   No sane engineer seriously takes the possibility o...   Aug 22 2003, 01:37
- - AstralStorm   The test was brain-damaged. Mangled sample and no...   Aug 22 2003, 02:21
- - Patsoe   QUOTE (AstralStorm @ Aug 22 2003, 02:21 AM)Th...   Aug 22 2003, 08:06
- - KikeG   External hardware decoding of 44.1 KHz PCM-encoded...   Aug 23 2003, 18:30
- - KikeG   And, even when hardware directsound acceleration c...   Aug 23 2003, 18:35
- - Peter   That's because kernel mixer was designed to pl...   Aug 23 2003, 18:52
- - KikeG   Yes. But if I play something, I'd better prefe...   Aug 24 2003, 20:58
- - Patsoe   QUOTE (KikeG @ Aug 23 2003, 06:35 PM)So, in p...   Aug 24 2003, 21:52
- - KikeG   QUOTE (Patsoe @ Aug 24 2003, 09:52 PM)Well, i...   Aug 25 2003, 20:16


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: 23rd July 2014 - 00:14