[leeperry]

Quote:

Originally Posted by D0gbert /img/forum/go_quote.gif the conditions are easy to meet.

well from what I understand, they're supposed to be simple :
-all volume controls set to the max
-only one audio stream

...right ?

I was using my M-Audio Audiophile USB w/ the latest drivers in DS/MME....then I've found some old drivers from 2003 where MME bypasses KMixer, and the improvement was very impressive

this card doesn't have a windows mixer at all, and I only play one stream at a time.

also the output was louder with KMixer bypassed, should we guess that the newest drivers don't set the volume to the max in the Windows Kernel ?

anyhow, when you've tried fullproof bitperfect, I still rest my case...there's no looking back

 

[D0gbert]

I've tried to explain it in detail here: Bitperfect - cmediadrivers - "Bitperfect" / "bit-exact" explained - Google Code

 

[leeperry]

Quote:

Originally Posted by D0gbert /img/forum/go_quote.gif I've tried to explain it in detail here: Bitperfect - cmediadrivers - "Bitperfect" / "bit-exact" explained - Google Code

yeah thanks, I read your page.....anyhow, I don't wanna use DS no more

 

[thomaspf]

Quote:

Originally Posted by D0gbert /img/forum/go_quote.gif That's incorrect: the kmixer of XP/2k doesn't resample everything, on the contrary, it can be bitperfect if some conditions are met. The audio service of Vista/7 does indeed some audio processing even though it isn't required, but I doubt that it resamples the audio unless it is necessary.

This is correct except for the volume processing on 16 bit data with kmixer. On Vista unity gain is no problem since it is simple to multiply with a floating point 1.0 value.


The uneccessary processing is dithering which should only be applied if there is any truncation happening. For 16 bit data there should be no truncation for the conversion to and from a float but the conversion and dithering algorithm in Vista touch the lowest order bits no matter what.

If you put 16bit data into the highest order bits of a 24bit sample the data makes it through unmodified.

Cheers

Thomas

 

[NGX]

Hey folks. I'm having a hard time getting ASIO to work with anything. I installed the driver (ASIO4ALL), but it's nowhere to be found when I want to select it as output in Winamp and Foobar2000.

 

[indjke]

Quote:

Originally Posted by MerlinWerks /img/forum/go_quote.gif Hi Thomas, Quote: Unfortunately kmixer changes the bits in volume control stage even if the volume is set to 100%. I would like to read more about this, what is your point of reference. Thanks

I agree . At least in Win 7 system mixer does definitely change sound stream at 100% level. And my point of reference is my own ears

Recently I'd been listening E.S. Posthumus's UNEARTHED (2001) losless rip and had unexpectedly heard clipping clicks

I'd been using foobar via DS and all digital volume controls were set at 100% / 0.0 dB (no EQs or enhancers).

I'd easily found that lowering volume in system mixer or player both removes clicks, so problem is not in bad, clipped record.. To prove this i'd opened wave made out of source APE in editor and it had not found any clipping. So record is OK (but must notice it has peak levels of -0.1dB that's why it had helped to pay attention to problem!).

I was almost sure that source of problem is windows mixer, and had tried WASAPI. No clipping at 100% volume! So, windows mixer at 100% does not pass bitstream "as is", instead it amplifies volume! And that's why -0.1 dB peaks became higher than 0.0dbFS and had turned out to clipping

After I had played with foobar's and windows settings i found that 1) if windows volume is set to 100% then clipping removal level is -1.5 dB in foobar, and, vice versa, 2) if foobars volume is 0.0dB, windows volume must be set to ~85%.

And finally i'd tried to reset all sound settings via Creative Control Panel, and i believe, had found more exact value. CCP sets volume to 87-88% by default. Why 87-88? In system tray tooltip it is shown as 88%. In device properties - 87%... But anyway, if use average (87,5%) it is equivalent of -1.16dB. I'd set foobar's volume to -1.2 dB and still had heard NO clipping

(and at -1.0 dB it had appeared again).

So, seems like "neutral" volume control in Win7 is about 87,5% and at "100%" it really increases volume by ~1.2 dB. (But maybe exact numbers can depends on soundcard?..

)

 

[Delerue]

 
Quote:

Quote:

Originally Posted by leeperry /img/forum/go_quote.gif there sure is, they changed the name but it still resamples everything....except it does it in 32 bits float instead of 16 integer.

That's incorrect: the kmixer of XP/2k doesn't resample everything, on the contrary, it can be bitperfect if some conditions are met.
The audio service of Vista/7 does indeed some audio processing even though it isn't required, but I doubt that it resamples the audio unless it is necessary.

Sorry to bring this discussion back again, but I've read all the topics about this and couldn't find a better explanation about 32 bits media players running on 64 bits Windows. In your article here you say that one of the conditions to have KMixer bit-perfect is: The player must be compiled for the same architecture that the OS was compiled for - e.g. 32 bit player on a 32 bit OS, 64 bit player on a 64 bit OS. So, are you saying that running, for example, XP x64 with Winamp x86 will make KMixer change the bits of the sound, thus messing with bit-perfect concept? How did you test this?
 
Thanks!

 

[xand1x]

Interesting thread. I just built a new system and I have a bit perfect ENVY24MT sound card (Onkyo SE-90) and on board audio output via optical only. I am getting HDCD (red light on my dac goes on) to be passed through via Direct Sound. The key to getting things "bit perfect" for me via direct sound was to go to the advanced tab in windows sound and change 2 things. 1) Set it to output 2 channel, 24 bit, 44100Hz    2) Uncheck the box that says "Enable audio enhancements". The results above imply that you can get bit perfect output via direct sound but it would be nice to find another method to verify if I am on the right track. Any suggestions?

 

[loserica]

I choose Kernel Streaming. Is good.

 

[xand1x]

Quote:

I choose Kernel Streaming. Is good.

Yeah i got KS working from my dedicated sound card. I find it difficult to tell the difference between DS and KS when both are optimized though. Probably just makes sense to stick with KS!