Is iTunes 8 streaming to Airport Express bitperfect on Vista?

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I have come across conflicting information on this...and thought it deserved its own thread. I also read some claiming that it is bitperfect on a Mac but not a PC. Because if it is not I will have to buy Airfoil but would like to avoid the expense if I can.

Anybody with technical expertise or user experience?

(Currently I use Foobar with ASIO or WASAPI so its bitperfect)
 
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Anonymous

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Thanks JD. Went thru PJPro's post, fairly familiar with what he discusses. Issue is there is no way to use WASAPI in iTunes on Vista as the Multiplugin software has not been updated for iTunes8.
 

John Duncan

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Though I did realise I was answering the wrong question, seeing as you're streaming.....

If somebody could tell me how to record the digital output produced by AE, I'd check myself with my laptop. Will investigate further...
 

manicm

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JohnDuncan:Though I did realise I was answering the wrong question, seeing as you're streaming..... If somebody could tell me how to record the digital output produced by AE, I'd check myself with my laptop. Will investigate further...

You've joined the Dark Side (Haymarket) young man? Now you'll have to behave
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Anonymous

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Hello,

Currently there is no way to achieve a bit perfect output from iTunes in the Vista environment. Some would argue though that the Vista audio engine is pretty good and question whether the difference between WASAPI (using say Foobar) and iTunes is audible. I believe they are audible - and afterwall, why should Vista resample my audio ? My own comparisons between XXHighEnd using WASAPI and iTunes did reveal a difference. XXHighEnd gave me an amazing soundstage set back just a little behind the speakers at the same time as making everything so easy to listen too. It's a similar story with MediaMonkey and ASIO - though maybe some of it is the placebo effect!

If certain conditions are met on XP then you can, I believe, achieve a bit perfect output from iTunes, depending on your audio card of course. A guy over a computeraudiophile did some tests and, with the soundcard unmapped, and windows volume control kept to full (or not loaded), system sounds turned off, he managed to confirm that the K-Mixer left the audio well alone. Obviously you need to make sure that your soundcard isn't one of the many that always resamples to 48khz, the XP standard.

I use MediaMonkey but the iPod Touch doesn't have as much control as it would using iTunes. I'm going to install XP on my Vista machine and give iTunes a try, comparing the output to Foobar etc.

Whilst bit perfect audio in iTunes is achieved on the Mac with no fiddling, I actually sold my Mac for other reasons. Mac users may smile at us Windows users when it comes to the above, but I wanted BluRay support and the iTunes HD downloads just do not cut it for HD playback. Upscaled standard def and 720 HD is not going to match full bit rate 1080p. Ever. That said, I believe that you could get around this by installing Vista on a Mac using Bootcamp - but watch out for those ridiculous Apple standards such as the mini displayport and check whether HDCP will be supported from Vista via this output. Think it will.

Neither OS is perfect. Mac OS, clean, easy to use, but you can only really do what Apple allows you to do, live within their contraints... Vista, messy, too many services running, needs configuring ... but hey, you're free to choose what you want.

Hopefully the above answers your question - though it was also a semi rant !

Remember also that using the Airport Express means your audio is limited in otherways. Before your audio get's to your DAC it's converted to ALAC (Apple lossless) on the fly. Whether this is again audible or not is entirely down to the individual. I for one simply don't want my audio touched, converted or resampled. A clean path straight to the external DAC is all I ask for ...

Whatever you end up doing though, by simply making sure your import your CD's uncompressed with error correction on means you're always starting off with a better file than any CD player. Error correction on the fly is simply not as good as error correction having been completed beforehand. This is the reason multiple magazines have agreed that the Naim HDX sounds better playing audio from it's hard drive than from the CD drive.
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Anonymous

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Matt,

The way to measure whether bit perfect output is achieved is to compare the original file with the one that is received from the output device, be it an Airport Express or whatever. Did you check this?

The encapsulation doesn't matter, since the original is encapsulated, sent, then the encapsulation is removed, leaving the original. If it has an impact on the sound then something has gone dramatically wrong. After all, any data that goes over a network uses this procedure.

I'm a bit puzzled by your comments about Vista and XP, where you seem to be describing analog output from the soundcard, which has a DAC built-in. Why do you need to fiddle with the settings on your sound card otherwise? It's data that's being sent over the network, not audio.

The point about the mac is that it has an optical out which feeds directly into the DAC, bypassing the DAC on the sound card.
 
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Anonymous

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I'm not describing analogue output, I'm speaking purely in the digital domain. I agree that digital output from a Mac is bit perfect - BUT only if you keep the volume within iTunes to full. Always use your amp to adjust the volume. PC: what you're forgetting is the software environment. I haven't got time to post a link to it now but go to www.computeraudiophile.com, the XXHighEnd thread under General, and find the post from me containing answers from questions I asked of the chief audio engineer at Microsoft at the time Vista was in development. He confirms the following: The K-Mixer in XP is awful. IF your audio is resampled then there are all sorts of artifacts. He described it as "the situation is pretty bad" .. However, with a soundcard that can handle multiple sample rates and not just the 48khz Windows XP standard, if you unmap your audio card, keep the volume at full (or don't actually load windows volume at all) then, depending on your card and drivers, the sound should be bit perfect. Check out dogbers cMedia audio drivers on the Google Code website, this explains things further and is a cheap way to achieve a bit perfect output in either Vista or XP (but limited to 16 bit, 44.1 - 96khz sampler rates). In Vista, the situation is better as the audio engine is extremely high quality. But it upsamples everything .. This may sound good but I just want my audio stream sent directly to my external DAC - not too much to ask.. WASAPI and ASIO allow you to bypass this upsampling. iTunes does not support ASIO or WASAPI. I hope the above makes sense. I'd suggest spending some time on www.comptueraudiophile.com and the Well Tempered Computer website by Roseval. WASAPI and ASIO were invented for a reason. I'll also add that there are some studies going on involving how media players can affect audio. For example, XXHighEnd may sound different to Foobar with both using WASAPI. Software also affects CPU usage which affects the draw on the power supply. Expect some measurements soon. Whether such items are audible or not I don't know though. I hope computer audio doesn't start going to the way of hi end hifi.
 
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Anonymous

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Matt,

Don't worry about the encapsulation, it makes not a shred of difference.

As far as itunes goes, and I'm talking XP streaming to the Airport Express, then my understanding is itunes encapsulates the file/data if required, then sends it off to the AE. I'm not sure where you think the soundcard comes in - this is essentially simple file transfer to my knowledge.

This is why there's no difference whether you use a mac or a pc (I'm assuming XP), if the file is the same, the file that is transferred is the same, and, assuming the DAC is the same, the sound should be the same.

If vista requires itunes to send data via the soundcard where the data could be modified, then there could be a difference, but surely Microsoft wouldn't do this.
 

cram

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Tarquinh: As far as itunes goes, and I'm talking XP streaming to the Airport Express, then my understanding is itunes encapsulates the file/data if required, then sends it off to the AE. I'm not sure where you think the soundcard comes in - this is essentially simple file transfer to my knowledge.

It's not the soundcard its the windows mixer which is part of the OS. My understanding is all audio goes via this unless you get into WASAPI or ASIO
 
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Anonymous

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That's my point. Audio does indeed go via windows mixer or the software that comes with the soundcard. However, we're talking data streaming here, so the soundcard gets bypassed. It's not audio, but data that's being streamed.

Just did a simple test: I disabled the soundcard and stopped related services on my XP laptop. Result? No change to the performance of my AE. OK, it's not a definitive test, but even so.
 
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Anonymous

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Kmixer etc is irrelevant when you are sending the data out over a network to the Airport Express.

The Airport Express is therefore Bit Perfect.

An Americian magazine (Stereophile) measured and verified this but I don't know if it is allowed to post a link.
 

cram

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Eddie Pound: An Americian magazine (Stereophile) measured and verified this but I don't know if it is allowed to post a link.

Found the site/article. Well you learn something new every day. Thanks

Tarquinh - though seemingly not relevant to this thread, the windows mixer is nothing to do with what soundcard you have installed.
 
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Anonymous

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I'll risk it:

http://www.stereophile.com/digitalprocessors/505apple/
 
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Anonymous

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Oh, I'm sooo sorry. I didn't notice the Airport bit ... I've been talking non-airport ... sorry !!!!

In which case I agree - it's bit perfect.

Apologies - there I am rambling on ...

Mind you, iTunes does convert it to ALAC. Whether that's a problem or not is up to you.
 
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Anonymous

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cram:
Eddie Pound: An Americian magazine (Stereophile) measured and verified this but I don't know if it is allowed to post a link.

Found the site/article. Well you learn something new every day. Thanks

Tarquinh - though seemingly not relevant to this thread, the windows mixer is nothing to do with what soundcard you have installed.

It's also not relevant to streaming, which is what I've wasted way too much time trying to explain. However, I have to say you're only partly right - have a look at this .
 

cram

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Eddie Pound: An Americian magazine (Stereophile) measured and verified this but I don't know if it is allowed to post a link.

I'm not sure that this article does verify the position in respect of PCs. Just read it now and if you read the methodology of the test he never actually mentions feeding the airport express from the PC. The PC is only mentioned as a tool for recording sound output by the airport express. I know its nit picking but it does leave some doubt.

Tarqinh - apologies I have not been using the correct terminology. Its not the Windows mixer application I'm talking about its Windows kmixer (as Eddie referred to).

However, doing a bit of googling I'm inclined to agree that it looks like it maybe bit perfect for 16/44.1 audio
 

Alec

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Not so long ago there was a really good post on the site arguing that all that stuff about turning off processes in windows doesnt really matter. I probably replied to it but have such a hard time finding my posts these days.

Hopefully someone remembers it, but then it may not quite relate directly to this thread.
 

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