FLAC to WAV Conversion

[leo]

When your straining to hear a difference its not worth worrying, at least you did compare

Only thing I can think of if it is down to the version of FW and Slimcentre/squeezecentre running which may cause varying results

[NRG]

Could be Leo...lets flip this the other way what combination of f/w and SC can you readily detect a difference with? I don't have a duet....

[leo]

Hi Neal,

I no longer have a SB3, I think it was Slimcentre 6.5.1 and FW81 or 83
Maybe the file types in advanced settings was different, I'm not honestly sure.

I did mention the difference between Flac and Wav is much smaller with SB compared to say using the pc's sound card or a USB to SPDIF http://theartofsound.net/forum/showp...1&postcount=15 its not really a problem for me, only reason I mentioned it is because of the first post, it would be interesting to find the answer why some folks get the difference yet others don't though, surely its got to be in the settings.
Software used for the USB was foobar.

For the Duet I use Squeezecentre 7.3.1 Receiver FW48.
I'm 100% sure FW55 sounds different to 48, worse IMO so I went back to 48

[Davo]

All



I represent dCS and we believe that it is possible to build your own media server (cheaply) that can be used as a high end source.
Here are some of our findings:
Windows XP, Vista and OSX all contain, by necessity, a conceptual mixer. The OS is designed such that multiple applications can each access an audio device concurrently. To do this, it may have to sample rate convert sounds, and adjust the volume of both of them to prevent clipping.
For most applications, this works very well – the user playing back his MP3s hears the alarm bell mixed in when his e-mail arrives. However, to do this the mixer may make choices which may be unacceptable to an audiophile.
Firstly, most audiophile users will want to listen to only the music, and not be distracted by random sounds. Secondly, any volume control will alter the bits output to the audio device, possibly losing resolution. Thirdly, if the mixer decides to sample rate convert the music, rather than for instance system sounds, then the audio will be unnecessarily degraded.
Owing to the fact that a PC may contain many tracks in many different sample rates, and more than one can potentially be played at one time, the OS must have a scheme to deal with this, which can involve sample rate conversion.
OSX
OSX uses a “fixed” output sample rate (set by the Audio Midi panel in “Utilities”). The user sets this, and OSX resamples everything to match this rate.
Pros The digital out never changes rate, and if the rate is set to the same rate as the file being played back, and all enhancements/volume controls are disabled, the output is bit perfect.
Cons If the user has multiple sample rates, he either has to change the output sample rate manually every time the source sample rate changes, or rely on the OSX rate converter.
Windows XP
XP uses a thing called “K-Mixer” to handle sample rate clashes and mixing. If the audio device is already playing a sound, and a second application attempts to play another, K-Mixer will resample the second sound to be the same rate as the first. Otherwise, it does not perform rate conversion. A small volume adjustment is always in place (this is benign if the output device is 24 bit capable, not so if only 16 bit capable).
Pros If a user uses only one audio program, and has a 24 bit capable device, the output sample rate will change to meet that of the source material with very little degradation.
Cons Tricky and application specific to bypass K-Mixer for truly bit-perfect output.

Windows Vista
Windows Vista notionally uses a similar scheme to OSX – in the “Sounds” control panel, there is an “Output Sample Rate”. When using general purpose programs that use DirectSound (e.g. Windows Media Player), it works much the same as OSX – all audio is resampled by the OS to that set in the control panel. Similarly, the output can be bit perfect if the source rate matches the output rate. However, Microsoft have introduced a mode called “Exclusive”. In this mode, applications can talk directly to the sound hardware, bypassing all mixers, rate converters etc. using an API called WASAPI. The author is not aware that there are any fully working WASAPI implementations at present.
Pros Has the potential to combine the benefits of OSX for the casual user, with the pure-audio path and auto-rate switching an audiophile requires.
Cons Doubts as to whether WASAPI is fully ready, lack of software using this mode. Poor rate converter (see sample rate converter measurements).

Workarounds
Freeware available on the internet allows ASIO playback from Windows Media Player & Foobar, using both Windows XP and Vista. Use of these “workarounds” allows the application to select the sample rate, and guarantees the output from XP & Vista to be bit perfect. We are unaware of any software that allows iTunes to play back multiple sample rates without the Digital component (e.g. Upsmapler or DAC) being used for source rates that don’t match the selected output rate.
Summary
It is perfectly feasible to achieve bit perfect output from Windows XP, Windows Vista and OS-X. Choosing the interface carefully, together with being aware of what can be going on “behind the scenes” can result in a PC/Mac source that meets every criteria ( jitter performance, etc ) needed to be a “True High-End Source”, which combined with the convenience and flexibility make PC based audio almost irresistible.

[purite audio]

Davo Hi, interesting post ,will DCS be making their own 'server' , have you tried the various implementations you discuss ,and if you have do you have a favourite.
Thanks Keith.

[Audiocom AV]

It is perfectly feasible to achieve bit perfect output from Windows XP, Windows Vista and OS-X. Choosing the interface carefully, together with being aware of what can be going on “behind the scenes” can result in a PC/Mac source that meets every criteria ( jitter performance, etc ) needed to be a “True High-End Source”, which combined with the convenience and flexibility make PC based audio almost irresistible.

Hi

Thanks for your input.

This information is encouraging.

Best Wishes
Mark

[leo]

Nice post Davo! plenty there for us to be chewing on

I also came across this whilst browsing, not had time to read through it yet http://imageevent.com/cics/v03theart...gcomputertrnsp