New Features, Possibilities, and Modes

The main new audio processing features of the X-Fi line are the 24-bit Crystallizer and CMSS-3D. These features, as well as the onboard RAM and the three modes of operation (gaming, entertainment, and creation) will be explored in this section. We know what each of these features is and the basic principles on which they operate. While we could make a much more thorough analysis of the quality of these features, if we had some actual math to go on, it is understandable that Creative would want to protect their investment by keeping the intimate details of the architecture private. What we do know should be enough to go on for now.

The 24-bit Crystallizer

The 24-bit Crystallizer takes 16-bit audio and tries to add dynamic range to the audio signal. If we were to convert our 16-bit audio stream to 24-bits, we could essentially do so by adding 8 zeros to the least significant end of each sample. It becomes clear that the highest value that a sample can take on is much less than the highest value possible with 24-bit audio. Likewise, on the low end, the audio stream isn't capable of representing values between zero and 256. The basis of the 24-bit Crystallizer is to fill in these least significant bits with meaningful data and thus, expand the dynamic range of the audio. What, exactly, is meaningful data in the least significant bits? We're glad that you asked.

Audio engineers are big fans of compression. Applying compression to a sound decreases the dynamic range of a sound in order to preserve the loudest and quietest parts without clipping or burying the subtleties in noise. This is very necessary to make good use of 16-bit audio, as things like whispering over a snare hit are not easily representable otherwise. Knowing the basic manner in which audio engineers go about applying effects to sounds, Creative can try to reverse-engineer the process to add more data where it seems necessary.

Details on the technique are fuzzy at best, but we do have some information. The algorithm doesn't simply expand the audio signal; it looks for recognizable patterns in frequency and time and applies algorithms that fill in the data where necessary. For instance, the X-Fi hardware is able to detect something like a kick drum hit and use the sound and proportionally weighted, transient, low-frequency data to boost the impact of the event.

The algorithms focus on the energy flux in different frequency bands in order to localize the impact of the effect. This means that things like snare and symbol hits, the plucking of strings on an acoustic guitar, the slapping of a string on a bass, and gunshots in games should all become more distinct. Each sound will be enhanced according to its energy flux, frequency, and waveform. Creative states that this can even help clean up the high end on MP3 encoded files. What this doesn't enhance quite as well are quiet subtleties in the audio signal.

CMSS-3D

For 5.1 sources played on headphones with CMSS-3D, Creative uses HRTF (Head Related Transfer Functions) to virtualize the position of each audio channel around the listener. This technique is augmented with simulated environmental reflections, which attempt to improve the externalization of sound to the listener. These environmental effects are more subtle than the Dolby Headphone effects and are meant to convey a listening environment that matches the recording rather than one that fits the room in which the listener is sitting.

When enabled for 3D virtualization with two speakers, the methods used are similar to that of the headphone implementation. Rather than adding environmental reflections, this CMSS-3D mode includes a cross-talk canceller to make sure that signals from one speaker are not destructively combined with signals from the other at the listening sweet spot. Unfortunately, there is still a sweet spot for listening to audio in this mode, but settings like speaker angle are easily adjustable.

Probably the best use for CMSS-3D has nothing to do with two speaker setups. Getting the most out of a 7.1 channel audio setup is much easier with CMSS-3D. We still don't recommend using CMSS-3D for stereo sources, but for listening to 5.1 audio, CMSS-3D will do a good job of fitting the 5.1 sound to 8 channels. For creating a multi-channel environment with a two-channel source (if we absolutely must), our favorite solution is still Sonic Focus' implementation on Intel hardware. It's a shame that they won't open up their software for other hardware.

64MB onboard RAM

The top two models in the X-Fi series feature 64MB of SDRAM on the sound card itself. This feature is called X-RAM, but that isn't a technical term. X-RAM is a marketing name given to maintain the X- moniker of the card itself. This RAM is supposedly included to enhance the performance of games. Until games are written to take advantage of this feature, we will have to simply accept the possibility for performance improvement.

Creative has shown us some numbers that they have run using UT2K4 and a special patch that allows for playing over 100 voices at a time (currently only 30 are supported in the game), as well as uploading uncompressed sound files to the onboard memory. The numbers show a pretty big performance improvement when X-RAM is enabled in this case. Unfortunately, we don't know how real world this test is. Without having the patch to test ourselves, we can't really know what's going on. If we are more than tripling the number of concurrent voices, we would hope to see some sort of quality improvement as well. A performance improvement for a feature that isn't necessary is a useless test.

We really need to spend more time with games that currently support X-Fi to see if we can find a case where the extra RAM affects performance. Our best guess is that we won't see real impact from this feature until developers realize that they can target the Creative solution to deliver a higher quality audio experience. Playing audio with higher sample rates, adding voices, using uncompressed audio to save CPU overhead, and freeing system RAM for other uses should be quite attractive to audio designers.

3 Modes of Operation

The final major feature is the inclusion of three distinct modes of operation. This feature is necessary because of the complexity and flexibility of the Audio Ring architecture. Tradeoffs are necessary for every type of audio application, but a configuration that can switch between modes depending on the task at hand could be a major development in the "one size fits all" audio department. These are the features of the different modes.

Gaming Entertainment Creation
Video Game Frame-Rate: YES NO NO
Hardware 3D Audio Processing: YES NO OPTIONAL
Environmental Effects: YES OPTIONAL OPTIONAL
High-Resolution Audio Playback: NO YES YES
Audio Enhancement Processing: NO YES OPTIONAL
2-Channel to Multi-Channel Up-Mix: OPTIONAL YES NO
Multi-Channel Audio Recording: NO NO YES
Hardware MIDI Playback: NO OPTIONAL YES
Hardware Effects: YES YES OPTIONAL
Sample-Synchronized Record and Playback: NO NO YES
Low Audio-Streaming Latency: NO NO YES
Bit-Accurate Audio Capable: NO OPTIONAL YES

Professional recording requires low latency, especially when using ASIO drivers. Therefore, it makes sense that Creative would implement a mode targeted at getting audio in and out of the Audio Ring as fast as possible. Effects possible in Creation mode are limited to those that can be performed very quickly, and audio comes through the chain as unmessed as possible. Less than 2ms latencies are possible in this mode. Again, our only complaint with the Elite Pro as a professional solution is its lack of balanced I/O.

Entertainment mode focuses on the music and movie experience. Options for enhancing both stereo and surround sources are pushed to the foreground and features like the 24-bit Crystallizer and CMSS-3D will likely be heavily used in this mode.

Gaming mode is optimized for creating a multitude of hardware accelerated voices and processing them to create the best real-time 3D that audio developers can throw at it. With up to 127 3D + EAX voices, extremely complex effects are possible. Under this mode, X-RAM can be used to assist in the storage and playback of audio files.

X-Fi Processing Elements: The Quartet DSP SoundBlaster X-Fi Elite Pro
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  • JNo - Thursday, September 1, 2005 - link

    In fact, if Anandtech could do a review of the HDA X-Mystique 7.1 it'd be appreciated as I've heard quite a few good things about this card, not least its reasonable price point and dolby digital live output.

    By the way, on a separate note, for all the people here giving anandtech grief, people should look at more than just one site before making informed purchasing decisions and anandtech did much better than tomshardware which was extremely partisan. Also, I would like to use and trust dedicated sound sites like www.3Dsoundsurge.com but unfortunately they are often too slow in reviewing new hardware...
  • DerekWilson - Tuesday, August 30, 2005 - link

    you can output sound digitally ... dolby sources (DVDs) can be output to a reciever, and audio can be output via SPDIF to a reciver as well ...

    What you can't do is take a source that's not already dolby (like music, games and the like), encode it to dolby, and then send it to a reciver.
  • Lwood - Tuesday, August 30, 2005 - link

    I found this on the ALSA mailing list (http://www.gossamer-threads.com/lists/linux/kernel...">http://www.gossamer-threads.com/lists/linux/kernel...:

    "We are not going to get any support from Creative for the X-Fi chip.
    We do not get support from Creative for any Creative chip that has a DSP
    in it."

    It looks like we won't see a Linux driver for the X-Fi anytime soon... :-(
  • sprockkets - Tuesday, August 30, 2005 - link

    Oh well, even nVidia's soundstorm worked in linux, and with the 5.1 encoding out.
  • Reflex - Tuesday, August 30, 2005 - link

    I've had these cards in my lab and all I can say is that this is the first time I've ever really doubted Anandtech's credibility. This reads like a spiced up piece of PR from Creative, and subjective listening would not put this as the best consumer audio solution as so prominently stated on the first page of the review.

    Derek - What the hell is going on here? You don't even include any results from competing products to make such a statement. The war was over before a shot was fired is the impression this review gives. The fact that Creative finally has a card to match the specs that otehr cards have had for three years now makes it a 'revolution'? Sorry, I have been working with these cards for months now and they definatly are nothing special. Just expensive.
  • flexy - Tuesday, August 30, 2005 - link

    100% agree...tried to keep my complaints back, tho.

    Btw. nice nick :)
  • DerekWilson - Tuesday, August 30, 2005 - link

    Hello,

    We will be looking at more cards, and including an envy24 based solution is something that we intend to do in the future.

    We do include a result from a competing solution -- the Gina 3G is a pro audio card which has excellent audio quality. The Elite Pro is closer to a pro audio product in the component selection and construction.

    envy24 based consumer products don't score as well as the Gina 3G from what we have seen. Granted we do have to test this for ourselves, but we would certainly expect the Gina 3G to outperform something from Terratec or M-Audio.

    That being said, the X-Fi outperforms the Gina 3G in just about ever test we ran.

    It is very difficult to subjectively compare audio between cards. There have been some cases (the audigy line) where there was a very clear problem with the aural experience. With the X-Fi line, we can no longer say that we can hear problems with the audio.

    We spent days listening to this card, the Gina, and the Audigy 4. We frankly disagree with the statement that subjective listening does not put this card on par with the best audio solutions out there. We found no reason in our subjective listening tests to conclude otherwise.

    On top of that, after simply listening to the card for days, we ran the RMAA tests. These tests showed clearly that not only was the card void of any issues, but that the quality of the output was much closer to the source than any other card we tested. These two points add up to the conclusion you disagree with.

    And as we said, if this card performs better than the Gina 3G and the Gina performs better than consumer level envy24 parts, it stands to reason that the X-Fi would outperform just about everything but a LynxTWO ... and even then we would need to run some tests of our own ...

    The big problem is that at these incredibly low noise levels, high dynamic range, low distortion, good separation, etc... it is very difficult to hear differences in the audio. To the average person, the audigy 4 Pro, Gina 3G, and X-Fi will sound exactly the same. To a hardcore audiophile, we wouldn't doubt it if the X-Fi won their hearts. The X-Fi (in spite of its features) can provide a very true-to-the-source signal with less coloration than all but the best pro audio cards out there.

    For musicians, the high quality provides a better platform for work than the rest of the pack -- unless, of course, balance audio is desired.

    Show me a consumer audio card that matches the specs of the X-Fi ... From the tests other people have performed on the LynxTwo B at 16-bit/44.1kHz (the unofficial standard in PC audio quality), the X-Fi posts http://audio.rightmark.org/test/lynx-two-b-1644.ht...">better numbers in every category but frequency response (and it's darn close in that area)...

    The high end components used do not make the X-Fi Elite Pro "nothing special" ... They make it nothing most people will need. And certainly, between this and other products that use good quality components, most people won't notice much (if any) difference.

    We very much agree that the card is too expensive. And please rest assured that we will be comparing this card to an evny24 based solution -- and hopefully a lynxtwo -- in the future.

    Thanks for the feedback,
    Derek Wilson
  • yacoub - Wednesday, August 31, 2005 - link

    Look into the BlueGears X-Mystique. It's pretty much the best PC soundcard available at a reasonable price right now - and it's not Creative so there's no assorted bloatware to install.
  • Reflex - Tuesday, August 30, 2005 - link

    Derek -

    I am not trying to bash you here, however you have to understand that when you start an article by proclaiming something the best in its class, but then your test does not include the other solutions in the class at all, that things seem fishy.

    I work with audio devices for a living. I've worked with the X-Fi since it was a prototype(as have a couple dozen other people in my lab). Certainly it is an improvement over previous Creative efforts, and at first we were a bit wowed by the paper specs and proposal. However after working closely with it for months, I honestly can say that no one here feels its anything special. Perhaps some of that is the novelty wearing off, but in any ad-hoc test with someone who hadn't heard it before, they could rarely tell the difference between it and an Audigy, and the M-Audio Revolution generally was said to produce clearer sound. Not that our tests were scientific or anything, we weren't trying to write articles for publication.

    I'd really suggest some blind tests with a variety of content. I think you may be suprised to find that while for MP3's the X-Fi sounds good, for CD's and especially SACD's the mid-range is poorly reproduced. Make certain you use a wide range of music, and prefferably classical numbers that you know very well.

    Something else is you could list what type of speakers/headphones and recievers you are using, if you are testing with something like Klipsch then your credibility would go down considerably for anything but games and action movies, after all the card cannot make up for poor speakers(when measured by reproduction accuracy, not volume).

    I would suggest establishing a baseline and going from there. Based on my experience, in the 'consumer' segment the M-Audio Revolution 7.1 is a good baseline, however any baseline that you could compare against would be beneficial to strengthening the credibility of the review. Granted anything audio is subjective, but when you say something is 'better' you need to at least be able to point to some specific reasons as to why.

    And finally, the section that read like Creative marketing PR was your explanation of their audio architecture. There is nothing inherantly 'better' about the approach Creative is taking, it is simply different, there are both advantages and drawbacks. Furthermore, while they make the product seem like the 'next generation of audio' no one has managed to get a commitment from them to support the upcoming Windows Audio Architecture that will be a part of Vista, without that support they will be behind several others. Their lack of support for Linux is also a drawback for many.

    Thank you for the effort, I hope that this feedback will help you improve your audio reviews in the future. I have read AT since the beginning and rarely doubted what is posted here, there just seemed to be some rather glaring flaws in how this review was handled. At least in my humble opinion.
  • DerekWilson - Wednesday, August 31, 2005 - link

    Thank you very much for the helpful feedback. Some of your suggestions will absolutly make it into future audio reviews.

    I would tend to disagree with your assesment of Creative's architectural direction. If the intent is to very heavily process many audio streams, then the flexibility and power are helpful. This could be a boon to game designers or electronic musicisans looking for some hefty sample rate or dsp power.

    For straight up listening to a single source or recording the architecture is unnecessary.

    I agree that windows driver and linux support are drawbacks as well.

    We absolutely appreciate and need our readers feedback. Thanks for taking the time.

    Derek Wilson

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