iTunes bitperfect in windows

Why is this important?

The option is greyed out for me.

Bananahead, what version of Windows are you using, this option is not available in XP or possibly the 64bit versions of vista/win7.

Why is it needed? In short, in XP windows resamples audio in order to match sampling rates, so two sources can be played at once, ie a music source and a ding from windows. It uses 48khz as its base rate, CDs (there all my flac files) are 44.1khz, also to my understanding it also truncates 2 bits of data reducing the dynamic range too.

This is also an issue in Vista/Win7 but less so as long only one audio source is used, but windows will still resample if 2+ sources are you (ie a system noise). But the WASAPI addition mentioned above forces exclusive mode, so nothing can effect the audio stream.

If you google "effects of kmixer" or "bitperfect audio" there is alot of information on it and ways of getting around it, but this is the first time it has been available for itunes in windows.

quote:

Originally posted by Occean:
This is also an issue in Vista/Win7 but less so as long only one audio source is used, but windows will still resample if 2+ sources are you (ie a system noise). But the WASAPI addition mentioned above forces exclusive mode, so nothing can effect the audio stream.

While iTunes 9 allows use of WASAPI, I understand this is in shared mode rather than exclusive mode. Its still good, but less so than it could be.

Eloise

There are apparently exclusive and shared modes. In exclusive , Itunes would be the only program with an output and it would be directly outputing whatever bit rate was being played or selcted in the player. What I read wasn't related to W7 so perhaps things have changed and maybe a computer techie could fill in but even shared mode should be no worse than Mac OS and ASIO via a different player is still available to those that may want it. Looks like Itunes 9 may be better for everybody and no longer just MAC audiophile taylored. That Itunes have made their platform able to accomidate this in windows is very good news for the majority of computer owners.

As a reminder iTunes is always bit perfect via airport express streaming.

All content is transcoded to Apple Lossless for transmission to AirPort Express, including AirFoil-streamed content.

I thought Macs required NOTHING in terms of set-up. This is just as confusing as a PC. Dont foll yourself.

Allen,

It is very much the other way around. I own a MacBook and an iPhone as well as the Apple Blutooth keyboard. Seeing that I own three of their products I would say i do "have a thing about Macs" although not the way you intended.

I am not all-in on either side, both make great products. On the other hand I will never contend that Macs aren't hassle free, as they are marketed. Nor will I make apologies and excuses when problems arise.

They each have their own place in the world, and the market shows it.

-p

quote:

Originally posted by pcstockton:


I thought Macs required NOTHING in terms of set-up. This is just as confusing as a PC. Dont foll yourself.

This thread is about Windows machines and iTunes. Nobody has said anything about setting up Macs (except you)(and now me) .

Winky,

I misspoke. I intended to say "iTunes" not "Macs". Sorry about that.

My comment was directed at those who think Foobar/EAC is cumbersome, and iTunes "just works" (out of the box).

-patrick

Patrick your name is pit and you cannot dig yourself out of it. haha.

Perhaps apple is just trying to make itunes work better on a shit PC system,. ever consider that possibility.

Snigger.

quote:

Originally posted by Occean:
Bananahead, what version of Windows are you using, this option is not available in XP or possibly the 64bit versions of vista/win7.

Why is it needed? In short, in XP windows resamples audio in order to match sampling rates, so two sources can be played at once, ie a music source and a ding from windows. It uses 48khz as its base rate, CDs (there all my flac files) are 44.1khz, also to my understanding it also truncates 2 bits of data reducing the dynamic range too.

This is also an issue in Vista/Win7 but less so as long only one audio source is used, but windows will still resample if 2+ sources are you (ie a system noise). But the WASAPI addition mentioned above forces exclusive mode, so nothing can effect the audio stream.

If you google "effects of kmixer" or "bitperfect audio" there is alot of information on it and ways of getting around it, but this is the first time it has been available for itunes in windows.

Ah ok.

Win 7 64.

Thanks.

quote:

Originally posted by garyi:
Patrick your name is pit and you cannot dig yourself out of it. haha.

the "PC" in my name stands for "Politically Correct" come on!!!

quote:

Originally posted by David Dever:
All content is transcoded to Apple Lossless for transmission to AirPort Express, including AirFoil-streamed content.

Yes but what comes out is bit perfect wav for your Dac. The hdcd lightcomes on when appropriate. And as the Stereophile review states jitter is decent.

Eric,

Hmmmmmmmmmmmmmmm, are you sure about this?

Which are you doubting? That output is bit-perfect or that Stereophile's measurements are respectable?

On the former, what it sends out wirelessly is not going through the k-mixer and yes, it illuminates the hdcd light on my DAC (where appropriate), and yes, Stereophile also calls it bit-perfect.

To quote:
"Some audiophiles have dissed the AirPort Express on the grounds that its digital output is not bit-accurate. However, I found that this was not the case, that the data appearing on the AE's digital output were identical in the original file. To check this, I compared a WAV file with a duplicate that I had captured on my PC from the AirPort Express's S/PDIF output. I used iTunes on my PowerBook playing a version of the file encoded with Apple Lossless Compression to feed data to the AE. The files were bit-for-bit identical, proving that the AirPort Express is transparent to the music data (as is ALC, for that matter)."

On jitter from it's TOS-out:
"However, this performance becomes moot when the AE's digital output is used. The grayed-out trace in fig.7 shows a similar spectral analysis of the Musical Fidelity X-DACV3's analog output while it was driven by the AirPort Express via the Monster TosLink cable. The noise floor has dropped by 4–5dB, the word-clock jitter to a respectably low 258ps, which is actually better than the case with the standalone D/A processor driven directly by my PC's S/PDIF output (provided by an RME PCI card). "

That's not amazing, but the lowest I've seen them measure is in the 140s, and some stuff is in the 400s, so I agree that is respectable.

http://www.stereophile.com/dig...processors/505apple/

Noise is still an issue and jitter could be better when compared to a TC or HDX etc., especially clock jitter. Bit perfect(it is) is not to be confused with perfect bits and comparing to a very noisey PC through the mixer (if I-tunes is used as described) shouldn't be the standard for good regardless of card used.


Fabulous, useful device for distribution as is Sonos etc. but still not audiophile standard.
With new Itunes, Other than a quiet streamer (I'm not sure which are at this time outside something like an HDX, maybe a transporter?) a laptop/TC would seem the best scenario to get a quiet, low jitter dig out via wasapi/windows or a MAC as is. In this case, the PC 'may' be quiter if exclusive mode in Itunes is an option.
Perhaps with the new DAC, an Ipod touch may be good if the jitter solution is robust enough.

js - although that apparently negative quote is from the same article, it actually refers to the performance through the analogue output, which is quite irrelevant to the behaviour of an Airport Express into a DAC. Eric's quote, beginning "However ..", refers to the jitter performance from the digital optical output which is, as he points out, much more respectable. I'm looking forward to finding out whether that same output is good enough to get Sync on the NAIM DAC. Here's hoping.

Right you are. Early here. Thanks. My mistake and I've removed the quote to not mislead. I still don't feel it quiet or low jitter. Bit perfect, yes. I'm sure it will sync fine but suspect a touch may do better as, in theory, it could be quieter.

Bit perfect is perfect bits!

Only in storage.

Why?

Timing. The bits are just a string of numbers until they are "played" at just the right speed. Problem is, when devices try to transfer/process the correctly timed bits, they never (often?) quite get the synchronization right. The resulting errors in the digital signal are called "jitter" and manifest themselves as noise and other types of signal degradation in the final analogue output we hear.

The Naim DAC goes to a LOT of trouble to make sure this jitter thing is not an issue. Read the white paper.

Jitter, within reasonable limits, should not be an issue in the context of the NAIM DAC since it buffers and reclocks incoming data.

I still don't understand what js means by 'perfect bits'. Are some '1's better than others?

quote:

It's worth mentioning that jitter has to be at pretty high levels before it can be heard with any certainty.

I agree with you, I am really looking forward to hearing something such as a Sonos against a highend transport through the DAC. Since so far I have not heard anything sound better than my Sonos digitally through my Supernait, but if there is I am curious how much better it can be through digital.