Optimising Windows Audio Playback
Ok. I'm an IT professional. But I'm not an expert on Microsoft audio architectures. Nonetheless, I have done a little research into this and have produced this posting to provide some pointers for setting up Windows to optimise audio performance.
Windows XP
Windows XP provides a number of layers of software to process computer audio. This software architecture can/does impact the quality of the sound reaching the soundcard.
For example, Windows XP will support a number of concurrently running applications. Each of these applications may produce sounds. These sounds need to be merged together and sent to your soundcard for broadcasting. The software responsible for mixing of audio streams is the Kernal Mixer (or KMixer).
To simplify the job of mixing lots of sounds from different application, the KMixer resamples everything to 48kHz even if it is already at 48kHz (and doesn't make the best job of it). So your 44.1kHz audio stream from your media player is no longer bit perfect.
To get round this (and the latency introduced by all the operating system software) you need to enable your media player to connect directly to your sound card. To do this is you use Audio Stream Input/Output (ASIO) or Kernel Streaming.
To use either ASIO or Kernel streaming you need to have a plugin available for your media player of choice. These are available for Foobar2000 and WinAmp (ASIO, Kernel Streaming ). I am sure that many others exist (though see iTunes below).
Windows Vista
The audio software architecture is different in Vista. It has been completely rewritten to address some of the issues with Windows XP (see here). There is no Kernel Mixer in Vista.
The architecture provides an Application Programmers Interface (API) to support bit perfect streaming to the sound card. This is the Windows Audio Session API (WASAPI). It provides capability which is similar to kernel streaming but does not require the programmer to write complex kernel streaming code.
WASAPI supports two modes of use: shared and exclusive. In shared mode, audio streams are mixed and global effects (if specified) are applied before the stream hits your sound card. In exclusive mode the audio streams are not mixed and no effects are applied i.e. the audio stream from your media player is passed directly to the sound card.
To use WASAPI you will need a plugin for your media player and your sound card will need drivers to support it. Currently, I only know of Foobar2000 that has a WASAPI plugin. This operates in WASAPI exclusive mode only. The Creative Soundblaster XFi range supports WASAPI (but please check your specific model).
I have produced a How To thread detailing how to setup Foobar2000 to use WASAPI in Vista here.
See this thread if you want to use ASIO4ALL or find out a little more about the audio architecture in Windows (XP & Vista).
Mac OS X & Linux
Don't know a great deal about these but they do not seem to have as many of the mixer issues as Windows (perhaps supporting Ashley James's view that Apple desktops make a better audio source than PCs running Windows?).
iTunes
If you are running iTunes within Windows you are going to have the same issues as all other media players. Unfortunately, you are not able to work around the KMixer (in XP) or use WASAPI directly (Vista). If you desparately want to keep the iTunes frontend but want to improve sound quality you could check out this page. It details how you can set up iTunes to use Foobar2000 as a backend processor using the Multi-Plugin. I haven't tried this myself.
Sound Cards
It is worth noting that once you have set everything up to bypass the upsampling performed by windows that your sound also probably upsamples to 48kHz (check it's setting). If you can, set your sound card to 44.1kHz. If you can't, the upsampling performed by the card may be impacting sound quality. If you are using Foobar2000 you can add higher quality upsampling plugins to do the sample rate conversion rather than letting the sound card do the upsampling. I use this one. EDIT: Found out over the weekend that my X-Fi soundcard has an updated control console available allowing the selection of 44.1kHz, so I no longer need the upsampler
That's about all I know. Hope it is of use to someone.
31/12/2010 - UPDATE - iTunes & WASAPI
It would appear the iTunes now supports WASAPI on Vista and Windows 7 (32 bit versions). To enable WASAPI support, open Quicktime and select Edit | Preferences | QuickTime Preferences | Audio tab. You can select Windows Audio Session under "Play Audio Using." Some quick research on the web suggests that only shared (rather than exclusive) mode is provided. This means that your music will only be bit perfect if no other audio streams are present.
Well i like it 
Thanks al7478. But don't get me wrong. I'm not upset cos people don't like what I've said. People don't know what I've said cos not that many people have looked at it. I find that surprising and wondered why?
Good question.
1. Maybe the people who attend these forums who solely use computers as their source use itunes?
2. Maybe the people who use Windows as their source see themselves well versed in the subject?
3. Maybe no ones really bothered Mac/PC once their music is already playing?
4. Maybe no one likes you?
ÿ
Personally I'd like to see responses to all these questions [Except the last one in which I was only kidding].
Lol.
1) Maybe. But you can use iTunes within Windows and, as I stated above, with a bit of effort..
2) Agree. But even experts would have a look to see it what I was saying was wrong.
3) Maybe. I wondered if many people regard the PC as a substandard source (MP3, etc) so can't be bothered with improving its audio quality. They'd rather spend some money on some speakers.
4) Highly likely. I seem to have a knack of putting my foot in it or upsetting people on this site without even realising it.
Tis a mystery. thing is, i find it hard to settle down to put the advice into practice. ive only learnt to use pcs grudgingly at all, as a means to an end, so there are people far more savvy than me who woulod think now of it.
Mr Pro, dya fancy coming over for the weekend 2 sort my pc out?
Personally I would prefer a site such as this, an all encompassing one stop shop!
It would help if those at WHFI, the reviewers of such computer based sources would chip in here and post.
However, I do realize that those at WHFI probably can't spend a huge amount of time giving tips on DIY htpc systems and components compared to off the shelf solutions etc, and that would probably be left to computer based magazines...
I myself am planning a DIY htpc + server/NAS solution to play all my ripped cd's and dvd's, furthermore my goal would be to download all my HD film content as I am looking to cut out BD as a medium and storage, as well as future music (hi-res), however it would seem that as yet there is no complete solution that is satisfactory.
I have spent a lot of time researching various configurations and solutions, but so far I have not yet settled upon the media software to play all the content I require to the standard I require unless I have a few boxes and various media software, which defeats my goal of a one stop solution...
So far I have settled upon a DIY pc based solution as far as hardware is concerned, however, I have one eye on a mac mini solution if the hardware is refreshed and the media software would allow a more modular approach in regards to codecs and would allow for true 'audiophile' playback.
Fumanchu:Personally I would prefer a site such as this, an all incompassing one stop shop!
It would help if those at WHFI, the reviewers of such computer based sources would chip in here and post.
I suspect that there is more expertise in the forum community than necessarily within the WHFSV staff on this particular topic. It's surprising the number of IT professionals within the forum.
It's a good post PJPro, and I bet many windows users do not realise the missing potential they have.
On my PC system I now use XP/ Winamp and Asio, through an external soundcard (Roland Edirol UA 1EX), optical cable to Beresford DAC, and an Argon HA1 Headphone amp to Sennheiser HD595 headphones. Audio lubblyness.
(The cheap as chips Argon is a bargain gem imo, and improves greatly on the headphone amp in the Beresford, even if I find it a touch bass-shy)ÿ
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(I use Winamp over foobar as I am a lastfm subscriber )ÿ
PJPro, this is a good post, I suspect that many people are using a mac, as I am, or are too put off by the complexity of windows to consider it as a source. Certainly there are none of theÿup-samplingÿissues on a mac.ÿThe cheapness of something like the Apple TV with its digital optical out might also have an influence. The majority of my friends use a mac as a source for digital audio.
However I'll mention this post in a blog post I'm writing and add it to delicious etc, thanksÿ
Lots more in this vein on the computeraudiophile websiteÿ
http://www.computeraudiophile.com/mac_pro_osx_windows_vista_ultimate_64_bitÿ
Good resource.
pudley:It's a good post PJPro, and I bet many windows users do not realise the missing potential they have.
On my PC system I now use XP/ Winamp and Asio, through an external soundcard (Roland Edirol UA 1EX), optical cable to Beresford DAC, and an Argon HA1 Headphone amp to Sennheiser HD595 headphones. Audio lubblyness.
(The cheap as chips Argon is a bargain gem imo, and improves greatly on the headphone amp in the Beresford, even if I find it a touch bass-shy)ÿ
ÿ
(I use Winamp over foobar as I am a lastfm subscriber
Where'd you get your headphone amp? Can't seem to find it online.
I'd like to get the Stello HP100 (to compliment the DA100) and am seeing if I can strike a deal with the UK retailer for buying the two.
Also quite interested in the Little Dot Mark V. Dual mono headphone amp for £159 off ebay and it appears well received by a number of reviewers on dedicated headphone forums.
I wouldn't take it personally PJ, I gave up offering or asking for advice on this forum a few months ago as I found that generally either no answer is given or when an discussion was developed, with myself or another user, it tended to be around how poor a system was and how you would not get an acceptable sound without spending £1000s.
I also consider myself to be a IT Professional but am pleased to say I have learnt something from your post. If that is true with Vista it's about the first thing I've heard that makes me consider updating.
I once hated the idea of having to play music via my PC, but eventually gave in for a couple of reasons, my CD collection became too large and I got fed up getting up and down playing 1 song from one CD then putting another in etc., and secondly, cheaper larger hard drives meant that ripping to a lossless codec was not an issue. I know use my upstairs PC with iTunes Apple Lossless for transfers to my iPod and music back-up, downstairs is the home built HTPC using Vista Media Center and predominently WMA Lossless via digital coax to my Onkyo receiver.
Plus points: I now find I'm listening to more of my music collection for longer, quick and easy to change tracks.
Down side: not as good sound/fidelity wise as a decent CD player, fan noise.
I've found I get more detailed sound by sending a 96KHz digitally to my receiver which I play using the Onks Direct mode, I've found 44.1KHz to be too flat sounding.
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Slightly surprised at the low number of views this thread is getting. I can only conclude that
1) The number of users who use PCs as an audio source is not as high as I expected.
2) The majority of users who do use a computer as an audio source use an Apple computer.
3) Forum visitors are not interested in improving the quality of their computer based audio.
4) The thread got buried quickly and visitors are unaware of the computer based audio forum.
5) The title of the thread does not accurately convey the intent of the posting.
Which do you think it is?
My useful(?) What HiFi Forum threads can be found here.