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PostPosted: Wed Jun 02, 2010 4:54 am 

Joined: Wed Jun 02, 2010 4:33 am
Posts: 20
Hi,

So, let me start by saying I don't really have a need to do MPX/RDS in software...not that the idea isn't cool and something I want to play with in the future (I only stumbled on it while reading the help to figure out what exactly the interesting stereo processing was doing). Currently..I don't think I own any hardware capable of true 192khz to make me build a simple transmitter to play with the idea at the moment. But...really..the only reason I'm writing this post is to give some information about 192khz and Creative cards I discovered from an audio-engineer's pov. I don't know if any of this will be helpful...to anyone...I still felt the need to share it.

Let's start with the XFi. It's true that this card modifies any audio that comes in to it..that's part of Creative's huge claim was about the XFi DSP is that it was powerful enough they could run these complex DSP routines entirely on the card. I owned one of the first ones that came out and I will say this..it's a nice card. However, it had it's limits. First of all is that whenever the card (at least the first generation Platnium) was in either Gaming or Entertainment mode...everything got resampled. I still believe they ran this 48khz dsp limit that existed in all previous Creative cards...but with the XFi chip they could run better resampling methods. I will say this...the resampling engine they used was in fact quite good..if you like that sort of thing. Personally, I usually left the thing in Music Creation mode, which geared the DSP to pretty much do mixing...and if that wasn't enough, I usually enabled Bit Perfect mode...ensuring that the DSP chip didn't actually touch the audio...it was sent at whatever to the DAC's.

However, I don't think the Bit Perfect option is going to help getting proper 192khz out of it. Has anyone actually looked to see if it's capable of 192? I realize the specs say it is..and that's true...however...I do believe that the thing only runs 192khz when using the Creative DVD-Audio software...but seeing as I never really tried..I can't tell ya. I think the one time I tried to play 192khz to the thing using ASIO or a real-mode access in foobar it failed to initate an audio stream where as 96khz worked just fine.

Audigy 2 is an entirely different beast. This thing is plagued by the fact that the DSP is always on...requires a 48khz input...and if you're running 96khz, the upper half of the spectrum is basically mixed in with the DSP effects. No sophisticated resampling engine here...the same crappy intermodulation-distortion inducing mess of hardware they've used for a while. SOME of these problems could be solved by switching to the kX Project drivers...which while utterly and severely confusing for most people...once you figured out how they worked you could actually at least bypass the DSP and decode 96/24 directly using the "p16v" section of the card. Again...if you wanted 192khz playback you needed to use Creative's DVD-Audio stuff].

Now, honestly, I've been out of the Creative loop for a couple of years. When my last desktop blew up I discovered laptops had gotten powerful enough for me to do some audio work and there was a small demand for someone who was capable/willing to do quick-n-dirty mobile studio setups...however, maybe some of that is still relevant and of use.


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PostPosted: Sun Jan 20, 2013 11:59 pm 

Joined: Sun Jan 20, 2013 11:10 pm
Posts: 1
It has been ages since this original post and still this thread will pop up on Google's results when searching for X-Fi related topics.

I have learned a great deal about the X-Fi's in the last several years. I mean, I purchased my XtremeMusic in 2006! It's 2015 now and I'm 100% convinced this card was the single best purchase I've made in my entire life! Creative even claims it'll continue to support it with updated drivers for the upcoming Windows 10 OS!

Now, back to the topic, it is actually possible to get anything from 48KHz to 192KHz into the sound card without much of an effort. Note that 192KHz is only supported in stereo mode. On Windows, it's as simple as choosing the corresponding sample rate on the Audio section in Control Panel and you're off to go. Now, you can't expect exact bit-perfect audio in Entertainment or Game mode as the X-Fi chip will always do some (near lossless) upsampling in those operating modes. You can check this web page for more info on the X-Fi's SRC. The thing is, I've run extensive and thorough tests and I can guarantee that the X-Fi at least never downsample anything so you'd lose audio quality. The most it'll do in Entertainment or Game mode is upsample audio and, as it is super efficient at that, you can't possibly hear any distortion whatsoever.

If you really want bit-perfect audio, which doesn't make much of a point to me unless in very specific situations (like audio playback capturing using WASAPI or WhatUHear – I use that to clone Spotify songs... haha), you can always use Creation Mode and manually set sample rate to whatever value you also set the Windows Audio Control Panel (let's call it WACP from now on). Or you can use ASIO and have sample rate switched automatically for you.

I've tested ASIO in Entertainment and Game mode as well. It does seem to switch the cards master sample clock according to whatever your source audio is, but still the card will do some upsampling, so no bit-perfect audio unless in Creation mode.

OpenAL bypasses the software-based Windows mixer. It makes Windows Vista / 7 / 8 / 10 work just like Windows XP. It'll make the sound card do all the mixing and resampling in hardware instead of having Windows mixer do it for you.

You can have Windows Media Player or Foobar2000 use ASIO. With Foobar2000, you can also use OpenAL. The advantage is you can leave WACP set to, let's say 48KHz/24bit all the time and never worry about sample rate switching again as ASIO and OpenAL still use hardware acceleration and will have the card do everything for you at the highest possible quality. If you use the standard Windows sound system instead, that is whenever you're not specifically using either ASIO or OpenAL, then you have to keep changing sample rate in WACP manually all the time if you expect Windows mixer not to do any resampling on its own before sending the audio to the sound card.

Note: the current X-Fi driver for Windows 8 / 8.1 (SBXF_PCDRV_L11_2_30_0004.exe, released in March of 2014) has a bug in which, if you choose 44.1KHz audio in WACP, the sound will be heavily distorted. The workaround is play any 44.1KHz audio with Foobar2000 using ASIO as it will set the sound card master sample clock to a matching multiple of 44.1KHz instead of the standard 48KHz. If you do that with foobar, you can use 44.1KHz in WACP with no distortion whatsoever. Whenever you reboot your PC though, you have to do the thing with Foobar again to get rid of the distortion.

I keep on doing that, it has become religious already: do I want WACP set to 44.1KHz? Then I open a 44.1KHz file with Foobar2000 outputting sound through ASIO. Do I want to switch back to 48KHz in WACP? Then I open a 48KHz file with Foobar to get the sound card back to the standard master clock. Thus, I get no distortions in the current buggy driver.

If anyone needs help or wants to talk about the X-Fi cards, I'm very open for that. Just send me an e-mail to medeirosdez@yahoo.com.br with a clear X-Fi related subject and I'll be more than happy to set up a virtual meeting, like Skyping or using Google Hangouts or whatever.


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