X-Fi Processing Elements: The Quartet DSP

Audio effects and processing can be done on a CPU. The latest audio solutions from Intel employ software from Sonic Focus that performs audio processing without the aid of dedicated hardware. If an end user wishes to enable advanced filtering or processing features, the Creative X-Fi has the advantage of being able to perform these tasks without tasking the CPU (thereby freeing up resources for other applications).

As is often the case, a general purpose CPU is not the most efficient hardware for the job. The Quartet DSP is able to make quick and efficient work of audio data. As mentioned before, the Quartet is made up of 4 independent two-issue SIMD engines, which Creative calls a TIMD architecture for Thread Interleaved and Multiple Data. The configuration of the SIMD paths in Quartet lend themselves well to audio processing.

Creative didn't tell us how wide the data path is down each SIMD pipe, but Quartet is able to handle either integer or floating point data, making it more flexible than DSPs used on older Creative parts. Special instructions allow differing operations to be performed on SIMD data to enable more efficient audio processing. For instance, the FADDSUB2 instruction performs an add-on-one data path and a subtract on another. The DSP is also able to perform complex floating point math with the real and complex results completing in different paths.

In traditional DSP architectures, raw speed often wins out over programmability. Tradeoffs are always necessary, but the Quartet offers a good balance. The result of one instruction can be used in the next with no stalls or reordering necessary and any instruction can be performed after any other instruction without any conflict. Also, any register can be used as any operand in any instruction. While we don't have all the details on the hardware, a high level language compiler could easily target and optimize for this architecture.

At this point, an easy to develop and efficient compiler only really helps Creative write driver and feature code more easily. It could be possible for Creative to allow developers access to their compiler in order to develop specialized DSP code. We don't know if Creative will actually pursue this in the future, but the option is there should they choose to do so.

To sum up the capabilities of the Quartet DSP, we have this list of features:
  • 2 SIMD units per each of 4 simultaneous threads
  • fixed and floating point data supported
  • 235 opcodes
  • up to 1200 MIPS
  • can perform up to 4 moves per instruction
  • easy to compile and optimize
Bringing the entire Audio Ring architecture together, Creative has quite a powerful solution that can handle lots of quick and efficient processing. Multiple audio streams with multiple sample rates can be floating around, being processed and reprocessed with high efficiency and low latency. This gives Creative a good deal of freedom in how heavily they can process audio without needing any assistance from the CPU.

X-Fi Processing Elements: Exploring the SRC New Features, Possibilities, and Modes
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  • DerekWilson - Wednesday, August 31, 2005 - link

    we'll try it
  • Reflex - Wednesday, August 31, 2005 - link

    Well said, SDA. And yes, I also appreciate the maturity of AT editors. I do feel a disclaimer needs to be added to the article, that said they could easily have overreacted(as THG editors tend to).
  • Reflex - Wednesday, August 31, 2005 - link

    Derek - The concern I have is that your review, as it stands, is a ringing endorsement for a product in a market you do not fully understand. The users who rely upon Anandtech as their only source for this type of reccomendation are likely to purchase something like this, even though there are a wide variety of competitive solutions out there for a quarter of the price. I feel you should at the least post a disclaimer that your audio review process is a work in progress and make it very clear that you do not fully understand the market that the X-Fi is being marketed to, nor have adequate experience with competitive audio solutions.

    More damaging, from my perspective, is the fact that Creative has not pledged to support future standards or alternative OS's. On a $400 product it should not be obsolete in the 14 months between today and the release of Windows Vista. You need to at the least get a solid statement on whether or not the X-Fi will support the new audio standard natively, or if they intend to only support it in legacy interfaces. This is a sound card, not a video card, a user should not expect to have to upgrade in a little over a year.
  • PenGun - Tuesday, August 30, 2005 - link

    Try an M-Audio Audiophile 24/96. I used to run a TB Pinnacle which seriously kicked ass on all creative products including all the audigys I ran into.

    The M-Audio Audiphile is better. A very sweet card pushing the limits of what is possible with a switching power supply.

    After what creative did to Carmack there is no way I will ever buy their stuff again. As they continually make crap as far as I can tell, it's no problem.

    My card goes directly to Kimber braided, RCAs on the Audiophile, then to my Sonic Frontier's factory modded (mostly voltage control cicuits) SFL-1 Signiture preamp. From there we go to a pair of SFM-75 monoblocks, again not stock, running Svetlyna 6550B power tubes. That goes, biwired, on Tara Time and Space cables to a pair of BMW Matrix 1 speakers.

    I do have a revealing system eh' ;).

    PenGun
  • Eskimooo - Tuesday, August 30, 2005 - link

    would that be any good for games, too?
  • PenGun - Tuesday, August 30, 2005 - link

    It's pretty awesome actually. No hardware acceleration of course, but it's not a problem on my new Athy 64.

    PenGun
  • Eskimooo - Wednesday, August 31, 2005 - link

    hold on, no non-Cretaive card does EAX 3,4,5 at present...So it may sound awesome but you do not get max out of the game
    Does this card produce surround sound over the headphones? Call it gimmicks, but I'd be much interested in that. For practical space reasons and occasional nite gaming.
  • PenGun - Wednesday, August 31, 2005 - link

    Sound is what I care about. Positional audio in games is really not much more use than stereo. We can meet somewhere and see who walks away ... ;). Nexuiz is open source Quake,Quake2,Quake3 on steroids. Fun is back in deathmatch.

    I wonder why my account disapeared, I just recreated it but that is kinda strange.

    PenGun
  • blckgrffn - Tuesday, August 30, 2005 - link

    Where is it, dammit?!?!

    I guess I was unaware that the Intel solution had this ability. It may make sense to get a board featuring this ability to hook it up to my receiver, I can't believe creative can't figure out that we would really like to hook up a high quality card via a digital cable...
  • segagenesis - Tuesday, August 30, 2005 - link

    This is exactly why I got the HDA X-Mystique 7.1. I believe it is a licensing issue that Creative does not wish to bother with, or does not care to bother with. It's not a perfect card (minor control panel issues) but it does exactly what I want, and has great audio qualiy.

    It may not be as super ultra quality as this new card, but I would rather enjoy the fact it has DD 5.1 Live. The review kind of says it anyways, he mentions that using existing hardware compared... *ahem* this new "extreme" sound card doesnt really make an audible difference. If your onboard 5.1 sounds ok to you, why even bother upgrading?

    One thing that I find troubling is that game performance is slightly less with the X-Fi and considering Creative's lack of promtness with driver updates I would feel worried about optimizations.

    The last Creative card I owned was a SBLive! 5.1 and I don't really miss the brand.

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