QSound's 3D audio technology
Mikael Hagén Last revised on:4/5 - 99
Introduction
There has been much focus lately on Creative and Aureal's 3D sound cards but as we mentioned several weeks ago in our feature on Sensaura there are other companies that license 3D sound technology used for soundcards. Another such company is QSound. QSound's calls their 3D sound technology Q3D, which they introduced in 1991. QSound doesn't sell chips using the 3D audio technology. Just like Sensaura, they license their 3D audio technology to other companies. Some recent design wins for Q3D are Sega's Dreamcast, VLSI's Thunderbird (which Aztech's 368DSP card uses) and Trident's 4DWAVE-DX and 4DWAVE-NX chips. QSound's 3D audio technology is not only used by sound chips companies but has also been used in many games and a few other software applications like iQ and QCreator.
QSound's Q3D technology
Q3D can produce 3D sound with just 2 speakers or headphones just like the Live, A3D and Sensaura. For headphones (they call it Q2) they use the same approach, which is based on Head Related Transfer Functions (HRTF for short). HRTF filters are developed by putting microphones in a person's ears (or rather in a lot of people's ears to create an average) and moving a sound source around him so you know exactly what each ear hears for each position of the sound source. They use that info to create the 3D sound for headphones.
It's important to remember that even though HRTF are used by practically all 3D audio companies for headphones there can be quite a huge difference how good they are on placing the sound in the 3D space. How well it will work for you can be quite different than what a reviewer thinks, so it's a good idea, if at all possible, to try the soundcard out before you buy it or at least be able to return it if it doesn't work like you thought it would or should.
What makes Q3D special is their different approach to produce 3D sound for 2 speakers (called Q1). While the rest use HRTF together with cross-talk cancellation (a must for it to work well) QSound decided to develop audio filters specifically for the 2 speakers and they performed more than 550 000 listening tests before they finally were happy with the filters. QSound's method isn't superior to HRTF and cross-talk cancellation for sound placement but it has several benefits.
Maybe the most important is that their 2 speaker solution played back with headphones will still by most users appear like an improvement compared to stereo, even though you will lose most of the 3D sound experience. This isn't important with computer games where the user can choose if he wants to use speakers or headphones but for canned content like music it's a huge benefit and Qsound is aiming at more than the game market. Head Related Transfer Functions (HRTFs) designed to be used for headphones sounds bad on 2 speaker solutions and the same is true for HRTFs with cross-talk cancellation sounds played back on headphones.
Another benefit, and much more interesting for PC gamers, is that QSound's method is much more efficient. QSound's Scott Willing pointed out that "a review of 3D cards on the Hardgame web site concluded that the Maestro was a fast DSP solution when in fact it uses QSoft3D (w/Q3D 1.0), so the proof's in the numbers." Our Half-Life benchmarks demonstrated the low CPU usage and more details will be available in our upcoming review of Trident's 4Dwave-DX or -NX chip. These chips are showing about 5% CPU utilization with 32 3D channels on a fast computer even though the 3D processing is done by the CPU. A final benefit is that speaker placement is also less important than with HRTF systems as you are not worrying about cross-talk cancellation, but it isn't a huge difference.
The soundcards that will use QSound's Q3D technology will support DS3D, EAX and A3D 1.X by converting A3D 1.X calls to DS3D calls just like Creative and Sensaura do. QSound call their reverb engine QEM and the Trident 4Dwave-DX chip already has drivers available using QEM, which is part of Q3D 2.0.
Q3D 2.0 also supports 4 speakers and at this time they use conventional panning just like the Live and Monstersound. However, in the future they intend to use more advanced algorithms for 4 speakers and and has already generalized their underlying engine architecture
to support >4 speakers in next-generation products. My guess is that they will take the same approach that they did with their 2-speaker solution. The result should be better than 4-speaker panning and more like Sensaura's Multidrive technology where they use HRTF with both the front and rear speakers. Four speaker HRTFs is something the new LiveWare 2.0 will offer for EMU 10K1 based sound cards such as the Sound Blaster Live. The benefit of using some form of 3D processing with 4 speakers, and not just panning is it improves the effectiveness of sound placement to the sides, above and below you. When QSound finish their work of implementing more advanced algorithms for 4 speakers and a soundcard ships supporting that we'll tell you the result but within a few weeks we will be able to tell you how the Sensaura MultiDrive technology and Creative's Live!Ware 2.0 performs compared to 4 speaker panning which will give some indications how much of an improvement more advanced form of 3D process than just panning may provide. When we post the review of Aztech's 368DSP next week we will tell you how it compares to other cards using panning. It will probably be just as good as the Live and slightly behind the Vortex2 that uses HRTF for the front speakers and panning for the rear speakers. Trident's next chip, the 4Dwave-NX will also support 4 speaker configurations. Cards using the 4Dwave-NX chip should be available in US this spring."
QSound's 3D sound technology used for more than just games
QSound has used their Q3D technology to produce QSurround which is a Dolby certified 2-/4-speaker virtualization of DVD multi-channel audio. This could be used to play back AC-3 movies on a PC but for that to work with a soundcard using Q3D the manufacturer also needs to bundle a software DVD player that decodes the AC-3 signal just like Diamond did with the MX300 (but with the MX300 it is Aureal's A3D engine that is used for placing the sound with headphones, 2 or 4 speakers). QSound has several design wins with QSurround in the consumer electronic market, but I don't think any of the shipping Q3D soundcards bundle a software DVD player.
QSound also sells a program, called QCreator, with which you can create 3D sound files. QCreator let you use wave or AIFF mono sound files and place and move them in 3D space. The final result will be saved as wave file and produce 3D sound with 2 speakers. You can find an example of what QCreator can do at www.qsound.com/qcreator. At the qcreator site you can find more information about the product and download a copy for $25 if you wish.
QCreator is aimed to consumers but QSound also sells several tools for professionals. The only ones of particular interest to the enduser (and just those of you who have an interest in developing 3D audio applications or games) are QMDX and QMixer. QMDX is a free software development kit that will make it easier for developers to include 3D sound in their titles. It's main benefits are that it will allow the developer to write to one API that then will down mix to stereo if the sound card doesn't support DS3D. For 3D soundcards it will work just like any other game using DS3D except that QMDX includes a resource manager that will work on all soundcards. A resource manager is used to make it easier to take advantage of the limited number of 3D sources available on the soundcard (more details available in the DS3D article). If developers wish they can use QSound's QMixer which is an addition to QMDX that will produce 3D sound on non-DS3D soundcards using QSound's 3D sound technology. QMixer isn't free though. QMDX also supports EAX and QMixer will offer EAX even for non-EAX cards.
QSound offers more than 3D audio
QSound also offers 3 other sound technologies called QXpander, QMSS and 2D-to-3D remap.
QXpander is a stereo-to-3D enhancement process that will work with 2 speakers and headphones, called QX and Q2X respectively. However, at this time only QX are available but it seems to work quite well with headphones too but probably not as good as Q2X would. QXpander isn't really true 3D audio it's just a stereo expansion technique, which tries to wrap the stereo around you, so that you feel more surrounded by the music. The end result is hopefully a more compelling sound.
QXpander is supported by the soundcards using QSound's 3D audio technology and can be used to get a more compelling sound when you play CD audio, midi files and wave files with Trident's 4DWave-DX chip. QXpander used by soundcards doesn't work with direct sound games. For that you need to use QSound's 2D-to-3D remap (more about that below). Aztech also uses 2D-to-3D remap for wave files and uses QXpander only for CD-audio and DVD movies.
QXpander is also used in the QSound products iQ, iQfx and UltraQ. In all these products, unlike the version used with the sound cards, you will be able to use the stereo expansion effect even on mono sound.
IQ is a software program that allows you to use the QXpander technology on any sound that uses wave out. That means it will work with the system sounds, wave files, MP3 files and the Real Player. It won't work with CD-audio or midi files. It's possible that they will upgrade iQ later so that it can work with soundcards following the AC-97 spec, which allows them better control of how the CD audio is played. Basically, what they need to do is to mute the CD analog out. Future standards with MIDI may allow them to make it work with midi files too.
IQfx is a special version of iQ that is better integrated with the Real-Audio player and should mean less hassle for the end user. IQfx also offers a bass boost, which iQ doesn't. You can listen to a demonstration of iQ and iQfx on QSound's site. Personally I thought QXpander really made the audio much more compelling and clearly superior to a similar functions that my TV and speakers have. iQ and iQfx will cost you $15 and $30 respectively to download. The demo clips are free, so you can judge for yourself if it's worth the money.
UltraQ is a separate device that you can connect to any stereo output before you connect it to your speaker to produce the stereo-widening effect. It will then with all mono and stereo content. We will soon post a review of this device, which can be bought for $70 from QSound's website .
QMSS could be considered QXpander for 4 speakers and will be available on all cards using the Thunderbird 3D chip (Aztech's 368DSP sound card use it) and may also be available for cars using 4 speakers. We haven't had a chance to listen to it yet but according to QSound's Scott Willing "QMSS distributes the stereo image around the listener using four speakers by generating unique outputs for each. QMSS does NOT add reverb (one approach to 2->4 channel synthesis) nor does it merely copy front information to the back." It will be interesting to see how well it works.
The 2D-3D remap is used for direct sound games. With this method you takes stereo panning data and map it to a variable-width 3D azimuth for individual positional processing of the mono streams. This is instead of just processing the final stereo signal that is sent out to the speaker like QXpander does. 2D-3D remap should be supported on cards using QSound Q3D engine, but unfortunately I couldn't get it to work with the 4DWave-DX card so I don't know if it offers any improvement to QXpander. Hopefully Trident will release new drivers that includes this function.
QSound recently announced Q3D 2.0 that includes 3D sound support for headphones, 2 speakers, 4 speakers and QEM (QSound Environmental Modeling), which is compatible with Creative's EAX. QSound already has 2 new customers that will use their Q3D 2.0, Trident with its 4DWAVE-DX and NX chip and VLSI with their Thunderbird 128 chip.
Q&A with QSound's Scott Willing
For more details about Q3D 2.0 we decided to ask QSound's Scott Willing a few questions
What's new in Q3D 2.0 except the QEM part?
Behind the scenes there's always some subtle upgrading going on, like support for higher sample rates and higher-quality pitch interpolation. The rare opportunity arises to do some slight further optimization for speed, but IMHO this stuff is already the tightest code in the business. We have some deadly programmers!
We tend not to make a huge fuss about this sort of thing because we view it as part of the natural product progression. Platforms are continually getting faster, so one is able to support steadily more sophisticated algorithms as the available bandwidth makes them practical
Are there any enhancements to the 3D positional algorithms for 2 speakers or headphones compared to the Q3D based cards like Maestro1?
Only as noted above, plus the four-speaker output option
Will QEM support I3DL2 too or only EAX 1.0?
The implementations allow us to grow with the spec. The drivers will continue to evolve.
Is it the same reverb engine that is used by the Trident 4DWave-DX (2 speaker solution) and the soundcards using the Thunderbird 3D
Yup.
Trident uses QSoft3D but how does the Thunderbird Q3D chip implement Q3D 2 and QEM?
Q3D 2 = Q3D + QEM 1.0
QEM is done on the host; reverb is very memory-intensive
Conclusion
We will tell you more about what we think about QSound's 3D audio and reverb technology when we post our review of a soundcard using QSound's Q3D2 but you can find out for yourself what you think by downloading QSound's Q3D demo (file size: 3.5M). It will allow you to test QSound's Q3D for headphones, 2 speakers and compare it with your own sound cards 3D sound engine and MS DS3D software 3D sound engine.
You can also read any of our game reviews where we used the Trident 4Dwave-DX cards as one of our test cards but as you can see there are some issues with the current drivers that makes it impossible to test QSound's Q3D for headphones.
If you have any comments, questions or see any errors in the article contact Mikael@3dsoundsurge.com.
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