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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  • Reflex - Wednesday, August 31, 2005 - link

    Derek, please read the following http://www.microsoft.com/whdc/device/audio/uaa.msp...">article on Universal Audio Architecture. Between that and Intel's HD Audio spec, all the supposed benefits of the X-Fi driver architecture are achieved already, and in a standard fashion that other sound card manufacturers can follow. There is nothing unique about what Creative is offering, only the marketing surrounding it, and in fact its been on the market since Intel's HD Audio first came out.

    Multiple source/multiple channel audio is definatly a major application in the future, but Creative is not the company leading the charge on this, only following suit.

    Once again I feel that your article in its present state serves as an advertisement rather than an objective analysis. I am certain that was not the intention, however due to the lack of research it came out that way anyways.
  • HardwareD00d - Wednesday, August 31, 2005 - link

    Thanks for your post. I was thinking I'd upgrade from my Audigy2 to an X-Fi, but now I think I'll pass.
  • PenGun - Tuesday, August 30, 2005 - link

    Could not have put it better, thanks.

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

    guys, i'm looking for an HTPC config with dual-core AMD where i can use the opticl drive without turning on the PC...

    ...i know, seems a bit out of context; but if this card or any lesser ( ? ) can be used in such context, what product would you recommend ?

    i like the HP DEC form factor, but i'll take anything proven worthy WITH AMD DUAL CORE and and an optical drive independent from PC.

    thanks for feedback,
    cordially,
    a.
  • Calin - Wednesday, August 31, 2005 - link

    The ASUS boards have the capability to play audio CDs from BIOS (I remember something like that, I don't have the ASUS board/manual to check). Maybe if you start the CD it will play while your computer is stopped?
  • whymeintrouble - Tuesday, August 30, 2005 - link

    I believe HP has a media center pc that can run a dvd drive, but not need to be in windows to use it. I don't know if it has the option of the Dual Core X2s though.

    I want to see a few more reviews go up before I make my judgements on these cards.
  • RussG - Tuesday, August 30, 2005 - link

    This still won't make myself, and a lot of people, upgrade from onboard sound. What I would like to see is more comparisons of how this is going to affect my FPS in more then 1 game, and how it stacks up to common on board solutions. They bring out all of this marketing because realities are not many people care about sound greater then onboard, and with no game support or evidence of existing game improvement there is little reason to pick this up.
  • NeonFlak - Tuesday, August 30, 2005 - link

    I bought the $130 X-Fi last night at bestbuy. I haven't seen this mentioned anywhere but compared to all my other sound cards, including onboard sound, when listening to MP3s or any other sound format it is very muffled unless the crystalizer is turned on. But, just as the review says the crystalizer doesn't really work well with everything.

    Games sound fine though. I haven't tested any movies since I don't watch movies on my pc.
  • DerekWilson - Tuesday, August 30, 2005 - link

    Are you sure you don't have CMSS-3D turned on? I find that sound can get very muffled and muddied when playing music using CMSS-3D ... That could be your problem.

    Our experience is that the sound quality with no filtering is better on the X-Fi than most other solutions. Of course, we do still need to look at the XtremeMusic card.
  • knitecrow - Tuesday, August 30, 2005 - link

    Ok, SoundBlaster is the only game when it comes to games... but what about listening to music or watching DVDs?

    Does it sound any better than my $30 chaintech VIA ENVY24 card or M-audio Revolution? I would like to see some blind listening tests.

    You have many many software based solutions that claim to make mp3s and other lossy formats sound better, for example SRS WOW effects that come bundled with Windows Media Player or Qsound. Is the creative crystallizer any better when compared to such software solutions?

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