X-Fi and the Elite Pro: SoundBlaster's Return to Greatness
by Derek Wilson on August 30, 2005 11:59 AM EST- Posted in
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The X-Fi Audio Ring: Powerful and Flexible
Putting aside marketing buzz words and the slightly tacky Xtreme Fidelity moniker, the new generation of sound cards from Creative Labs is quite impressive. The technological advancements come from the inclusion of four key new features: the ring based architecture, a high quality sample rate converter, a powerful DSP, and on-board RAM. First on the chopping block is the Audio Ring.
Another reason why Creative may have chosen to support so many internal channels is so that it can handle algorithms that call for splitting or duplicating an audio stream for multiple different types of processing and analysis. This could range from using CMSS-3D (Creative's new surround upmixing feature) to efficient implementations of complicated high order N-tap and feedback filters. Creative doesn't talk much about the uses of these internal channels, but many of their new features include detecting aspects of the audio being played in order to enhance the sound. It seems likely to us that the algorithms that implement their new features would rely on the high number of channels and the flexibility of the ring architecture to get as much done at one time as possible in order to keep from introducing an unacceptable amount of latency.
Now that we know how the ring works, here's what each node on the ring does:
Transport: This handles moving audio streams in and out of local RAM as well as over the PCI bus to system RAM. The Transport engine manages over 1000 DMA channels to both the PCI bus and local SDRAM. Being able to manage so many DMA requests at a time is important for dealing with the latency of PCI and effectively managing the volume of data with which the new solution is capable of working.
Tank: Its name is based on the tanks that held mercury used to create high quality analog delay lines. The tank engine is capable of fractional and modulated delay lines (delays that don't line up with the sample pattern and delays that change over time). The tank engine supports up to 1024 accesses per sample. This means that the tank engine can assist in many types of effects including: chorus, reverb, reflections, and interaural time delays (for positional audio effects). These effects are employed quite a bit in many of the audio processing features of the X-Fi, so avoiding the use of a DSP for the creation of a delay line is very helpful in spreading out processing power.
SRC: The Sample Rate Converter seamlessly transforms any audio stream or channel to any other supported sample rate with very low ripple and THD+N. We will cover this node in detail as it is one of the key features of the new architecture, allowing Creative to convert the sample rate of all audio multiple times independently of any other audio with little to no discernable loss in quality.
Filter: The filter engine implements 512 floating point 2nd order IIR filters. This is the fundamental building block of sound synthesis, 3D spatialization, equalizers, speaker calibration, and a host of other features. There are 13 filter types implemented in hardware from direct and parametric 5 parameter EQs to notch and peak filters. Complex (higher order) filtering and synthesis can be achieved by looping through the filter engine multiple times until the desire result is achieved.
Mixer: Consisting of 256 audio summers, 1024 parameter combiners, and 4096 single segment parameter rampers, the mixer is where internal audio channels come together. Parameter mixing and ramping are used to control effects combining for things like 3D audio effects in game. Instead of single segment, the parameter rampers can also support either 1536 multi segment rampers or 4 multi segment shapes (possible shapes are linear, pseudo exponential, and pseudo logarithmic).
DSP: The X-Fi Quartet DSP is so named because it supports 4 hardware threads. Each thread has access to two SIMD (single instruction, multiple data) units for easy stereo and complex math processing. NVIDIA has called a multiple SIMD processing unit MIMD (multiple instruction multiple data), but Creative has dubbed the overall architecture TIMD (Thread Interleaved Multiple Data) due to the hardware threading support alongside traditional methods. The Quartet DSP is central to many of the X-Fi features and we will cover this hardware at length as with the SRC engine.
Audio I/O: This node handles moving the final processed audio streams to output either digitally or through a DAC, and can also acquire input from each of the source options on the hardware. Audio sources in memory do not enter the path through this node, and likewise for audio written to memory (or a file). This block manages all the physical I/O ports on the X-Fi card.
Having easy access to any of these structures at any time during audio processing will greatly simplify the process and increase the complexity of operations possible on X-Fi hardware. In order to further optimize the architecture, Creative has introduced three distinct modes in X-Fi. These modes outline the basic type of path that audio streams will take through the ring. For instance, professional audio programs require very low latency audio from the sound card when recording. In order to accommodate this, the Creation mode limits the types of processing done to less complex (and faster) algorithms. Creation mode also allows synchronized audio streams for proper integration into a studio setting. These features aren't necessary when in Gaming or Entertainment modes, as the focus of these modes is on generating or heavily processing audio before input or output.
Architecting the card like this isn't useful unless the nodes on the ring are powerful enough to exploit the potential. Creative has spent quite a bit of time in making sure that this is the case. Their components are high quality and introduce as little distortion and noise as possible in order to make heavy processing of audio on a consumer sound card a reality. (Whether this is really a good thing or not is still up to the end user.) Over the next couple of sections, we will cover the most important components of the audio ring, as well as explore what is possible when all of this hardware sings in unison.
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mindless1 - Wednesday, September 21, 2005 - link
Unless you can provide the technical means used, I will tend to disbelieve this as the card itself is evidence to the contrary. You can't do in software what the hardware doesn't "really" support and have same result. To get 44.1 out without resampling, you have to START with a 44.1 clock rate, have that specific frequency generator. You can't do "math tricks" to derive a 44.1 rate, it's just an end-run to same end- resampled.Resampling IS clearly a negative. "clean signal" is foolish talk in the context of audio, because typical distortion figures are not enough to discriminate what the human ear can. Proof-positive is that people can, reproducibly, conduct blind abx tests and discriminate between two different sources that have insignificant "measurable" signal differences.
Resampling is always considering one of the most significant factors, it destroys the music's detail to do it. If the rest of your gear is crap and you can't hear the difference, it matters less- but if you are buying this card I would HOPE it's not to be paired with low-end links in the rest of the system.
When you "set a clock", you are causing it to resample. Doing without resampling requires multiple clock crystals, at least the base frequencies if upsampled further for better DAC resolution on an analog output. You don't "set" a clock rate in such a superior scheme, only selecting (which) clock input.
Byzantine - Wednesday, September 28, 2005 - link
In Audio Creation mode you can set "Bit-Matched Playback" which will disable the SRC and any EQ. The X-Fi has a flexible signal routing architecture so that you change the sampling rate. The Digit-Life review confirms that you can play back at 44.1kHz without SRC.I guess you haven't auditioned the X-Fi yet, otherwise you would not notice how improved the SRC is on the X-Fi compared to the previous generation. Even if you did not like the SRC, there is now the option to avoid the SRC altogether. Music listening is very subjective, so there's no way people will agree on the quality of the sound. If the X-Fi is not up to your standards, then don't get it. I'm personally more than satisfied with my Elite Pro.
Sea Shadow - Wednesday, August 31, 2005 - link
How do you know this, I have yet to see any data proving or disproving your rantings.yacoub - Wednesday, August 31, 2005 - link
I'll consider it a return when they offer it for $100-200. This is nothing more than Creative moving to a price model similar to other computer hardware components such as videocards. The only thing returning is the bullsh*t.Araemo - Wednesday, August 31, 2005 - link
Hello? Anyone out there? Creative, 2004 is calling, and it would like a PCI-express audio card.More seriously, I'd be hesitant to spend $100+ on a new sound card for my new system(about 5 months away) that may not work on my next system after that(About 2 years away). Sound cards are not a huge performance bottleneck w/ only two speakers. I don't NEED a new card, so I'll probably just use the Realtek 850 audio on my next motherboard.
Why would Creative release their only innovative product from the past 5 years, without support for the most current interface? I'm sure they can add it down the line, but it doesn't make sense to me not to have it now.
xeizo - Wednesday, August 31, 2005 - link
There is no PCI-E soundcard out there yet, strange it may seem, but that must be because the industry had an easier time introducing PCI-E on motherboards than they expected, and so no need to push it further by rushing "killer hardware". Or mabe more right, the killer hardware was SLI.There are other much more interesting audiowork being done than X-Fi, like the team which are writing an audiodriver for Geforce-cards. There we can talk about a capable DSP, and with lots of "X-RAM" already in place.
As been pointed out, the most annoying thing about X-Fi are the driver issues:
no Linux-driver, or even support for external development of one
no Windows Vista-support
the general low quality of ALL Creative drivers, the slow updates or correction of bugs, the bloat, and not being able to download full drivers but must buy a CD.
And what about usability ? If I build a new computer, do I really need more audio-performance than what I have ? Yes, if I'm a musician I need "as much" audio performance as I can get, but I don't usually get it from a soundcard(or audiointerface) but instead I get it from software or dedicated hardware. What I need is a fast, faster, fastest cpu and lots of matching RAM. No need to even bother to use any part of Creatives software bundle, as there already are endless amounts of much better dedicated music-creating software out there. All i need is a fast PC and a clean sounding audio-interface. Even an Audiophile 2496 for under a 100$ sounds clean enough for professional use and has as low latency as the 400$ X-Fi, and the drivers aren't buggy. It just works, clean and simple. If I wan't to make music I would be much more interested in Creatives E-MU cards, especially since X-Fi are so insanely highly priced. The cheaper cards in the X-Fi line will NOT do to take make music on because they use inferior AD-converters, which renders the good enough DACs on them useless for recording live instruments.
For other use, ie games, gamers aren't audiophiles. They just want cool effects in their game, any Audigy-card will do for that. Analogue sound, that is, if you use SPDIF to good quality external hardware i guess there aren't many that can't do with an ALC850.
And pure audiophiles who don't make any music, just listens to it ? Well, if the musician who made the music thinks an M-Audio-card is good enough to create the music on I see no reason why an Audiophile can't think that the same soundquality as in the studio is good enough for him.
And movies ? SPDIF and ALC850 once again ... but i prefer my standalone DVD-player.
In fact, noone NEEDS X-Fi, it's just bloatware and marketing. Most people annoyed with their soundquality need better speakers, not better soundcards. Or prove me wrong.
Araemo - Wednesday, August 31, 2005 - link
Some agreements and counter-points:In my current system, I have an audigy(First gen) "mp3". And the nForce 2 soundstorm w/ dolby digital(I think? NF7-S v.2.0, I don't use dolby if I do have it thoguh). I have no room for a 4.1, 5.1, 6.1, etc.. sound system, and it would just annoy my roommates and neighbors. So I wanted to find a good, high quality 2.1 system w/ optical audio in.. I couldn't find one from any computer speaker company. In retrospect, I should have looked at home theatre type stuff? But that probably woulda been at least twice the price(Good speakers + good amp?, vs. my logitech 2200s for about $70). My audigy, due to drivers, or whatever.. crackles after the system has been on a while, and multiple sounds are playing(Winamp + any game?). The Soundstorm has SHITTY sounding midi playback. I have both cards installed and configured.. midis play through the audigy's hardware midi playback, are 'recorded' on the audigy without leaving the card, and played back through speakers hooked up to the soundstorm. If I get an ALC850 sound card, I'll probably have to do the same thing to get decent midi playback. Plus, as scary as it sounds.. Creative's drivers are the BEST among all the consumer 'gaming' sound cards. And they SUCK ASS. I know from experience that the intel chipset built-in audio isn't always as stable as my audigy was.. (At least on my first gen centrino chipset). So, no, not everyone can put up with just an ALC850.. 99% of people can, but anyone who has a collection of MIDIs and likes decent sound banks.. has to buy creative, or get dedicated MIDI hardware.
Doesn't PCI-E have a transport mode designed to give predictable latencies? I would think the ability to have multiple sound cards interacting with the controller 100% independantly, getting all 1Gbps(Per lane) of bandwidth, would be desirable for high quality multi-channel sounds. It IS refreshing to finally see another creative product that isn't based on the Emu10kX chips. And who knows, if ATI can make their drivers good enough that some people are saying they're better than nVidia(In certain areas), maybe even Creative can pull their drivers out of the gutter too.
DerekWilson - Wednesday, August 31, 2005 - link
That needs to be said quite a few more times ...
mindless1 - Thursday, September 1, 2005 - link
True, the speakers are usually the weakest link but that doesn't begin to make the sound card any stronger. Unfortunately as any audiophile will tell you, the better the /rest/ of your gear is, the more you'll notice the weakest link. Can't tell for sure from the pics but it doen't even look like Creative is using decent output coupling caps, which is sad on a $400 card.ceefka - Thursday, September 1, 2005 - link
Plus: would an audiophile be listening to his best CDs from a PC or a standalone high end CD player? I guess I could do without the background noise of a PC and I do not consider myself an audiophile.