Editing Environmental Audio Extensions (section)

==Technology==

EAX is a library of extensions to [[Microsoft]]'s [[DirectSound3D]], itself an extension to [[DirectSound]] introduced with DirectX 3 in 1996 with the intention to standardize [[3D audio effect|3D audio]] for Microsoft Windows, adding environmental audio presets to DS3D's audio positioning. Ergo, the aim of EAX has nothing to do with 3D audio positioning, this is usually done by a sound library like [[DirectSound3D]] or [[OpenAL]]. Rather, EAX can be seen as a library of [[sound effect]]s written and compiled to be executed on a [[Digital signal processor|DSP]] instead of the [[Central processing unit|CPU]], often called "hardware-accelerated".

The aim of EAX was to create more ambiance within video games by more accurately simulating a real-world audio environment. Up to EAX 2.0, the technology was based around the effects engine aboard the E-mu 10K1 on [[Creative Technology]]'s and the [[ESS Technology|Maestro2]] on ESS1968 chipset driven sound cards. The hardware accelerated effects engine is an [[E-mu Systems|E-mu]] [[FX8010]] DSP integrated into the [[Creative Technology]]'s audio chip and was historically used to enhance [[MIDI]] output by adding effects (such as [[reverberation|reverb]] and [[Chorus effect|chorus]]) to the sampled instruments on '[[Table-lookup synthesis|wavetable]]' [[sample-based synthesis]] cards (which is often confused with the "wavetable synthesis" developed by [[Wolfgang Palm]] of [[Palm Products GmbH|PPG]] and Michael Mcnabb in the late-1970s, however not related). A similar effects DSP was also present on Creative's cards back to the [[Sound Blaster AWE32|AWE 32]]. However, the EMU10K1's DSP was faster and more flexible and was able to produce not only MIDI output but also other outputs, including the digital sound section.

Developers taking advantage of EAX choose an environment for their game's setting and the sound card uses the mathematical DSP [[digital filter]] presets for that environment. The original EAX was quite primitive, only offering 26 presets and 3 parameters for more accurate adjustment of the listener parameters and 1 parameter for the sources. Each revision of the technology increased the available effects. ''EAX Advanced HD'' (also known as EAX 3) and up provide support for new environmental transitions, new effects, and multiple active effects. Further additions include smooth changes between EAX environment presets and audio occlusion effects (simulating a wall between player and sound source).

EAX was used in many popular titles of the time, including ''[[Half-Life (video game)|Half-Life]]'', ''[[Unreal Tournament]]'', ''[[Tom Clancy's Splinter Cell (video game)|Splinter Cell]]'', ''[[Tom Clancy's Rainbow Six: Rogue Spear|Rogue Spear]]'', ''[[Doom 3]]'', ''[[F.E.A.R. (video game)|F.E.A.R.]]'', ''[[Counter-Strike (video game)|Counter-Strike]]'', and ''[[Prey (2006 video game)|Prey]]''. These games support EAX 4.0 if audio hardware with an OpenAL-supporting driver is present. Because hardware acceleration for DirectSound and DirectSound3D was dropped in [[Windows Vista]],<ref>{{cite web |url=http://connect.creativelabs.com/openal/OpenAL%20Wiki/OpenAL%C2%AE%20and%20Windows%20Vista%E2%84%A2.aspx |title=OpenAL and Windows Vista |url-status=dead |archive-url=https://web.archive.org/web/20081013083759/http://connect.creativelabs.com/openal/OpenAL%20Wiki/OpenAL%C2%AE%20and%20Windows%20Vista%E2%84%A2.aspx |archive-date=2008-10-13 }}, Creative Labs</ref> OpenAL runtime software is required to enable EAX in many games, it still functions in Windows 10, although OpenAL was also discontinued by Creative. OpenAL Soft, an open source version of OpenAL, is still actively maintained, and can be used by game developers, and to enable EAX sound in older games.

Most releases of EAX versions coincided with increases in the number of simultaneous voices processable in hardware by the audio processor: the original EAX 1.0 supports 8 voices, while EAX 5.0 allows 128 voices (and up to 4 effects applied to each). Creative cards are generally backwards compatible with older EAX versions, although hardware accelerated DSP processing of these effects only happens on cards with EMU chips. Most audio solutions from Creative released after the X-Fi Titanium HD (except for the Audigy Rx) and other companies offer EAX software emulation of varying degrees instead.

===EAX 1.0===
*8 simultaneous voices processable in hardware
*32 individual 3D voices
*Environmental Effect Presets
*Per-channel individual environmental presets
*Hardware DSP rendering<ref>{{cite web|url=https://github.com/kxproject/kX-Audio-driver-Documentation/raw/master/3rd%20Party%20Docs/EAX/EAX%201.0%20(1998).PDF|title=Environmental Audio eXtensions|author=Creative Technology Ltd.|website=[[GitHub]]|date=August 31, 1998|access-date=January 20, 2018}}</ref>
*Specification released in 1998

===EAX 2.0===
EAX 2.0 is supported by [[Sound Blaster Live!]] sound cards
*32 simultaneous voices processable in hardware
*Occlusion Effects
*Material-specific reverb parameters<ref>{{cite web|url=https://github.com/kxproject/kX-Audio-driver-Documentation/raw/master/3rd%20Party%20Docs/EAX/EAX%202.0%20(1999).pdf|title=Environmental Audio Extensions: EAX 2.0|author=Creative Technology Ltd.|website=[[GitHub]]|date=1999|access-date=January 20, 2018}}</ref>
*Specification released in 1999

===EAX 3.0===
EAX 3.0 is supported by E-mu 10K-based products such as the [[Sound Blaster Audigy]]
*64 simultaneous voices processable in hardware
*'Smoothing' between 3D audio environments
*Direct access to all reverb parameters
*Environmental Panning
*New [[reverberation|reverb]] engine
*Beginning of the AdvancedHD Designation from new reverb engine

===EAX 4.0===
EAX 4.0 is supported by Audigy series [[sound card]]s.
*Real-time hardware effects
*Multiple simultaneous environments
*[[Flanging|Flanger]]
*[[Echo (phenomenon)|Echo]]
*[[Distortion]]
*[[Ring modulation]] effects<ref>{{cite web|url=https://github.com/kxproject/kX-Audio-driver-Documentation/raw/master/3rd%20Party%20Docs/EAX/EAX%204.0%20Introduction%20(2003).pdf|title=EAX 4.0 - Introduction|author=Creative Technology Ltd.|website=[[GitHub]]|date=November 18, 2003|access-date=January 20, 2018}}</ref><ref>{{cite web|url=https://github.com/kxproject/kX-Audio-driver-Documentation/raw/master/3rd%20Party%20Docs/EAX/EAX%204.0%20Programmer%27s%20Guide%20(2003).pdf|title=EAX 4.0 - Programmer's Guide|author=Creative Technology Ltd.|website=[[GitHub]]|date=November 21, 2003|access-date=January 20, 2018}}</ref><ref>{{cite web|url=https://github.com/kxproject/kX-Audio-driver-Documentation/raw/master/3rd%20Party%20Docs/EAX/EAX%204.0%20Sound%20Designer%27s%20Guide%20(2003).pdf|title=EAX 4.0 - Designer's Guide|author=Creative Technology Ltd.|website=[[GitHub]]|date=November 18, 2003|access-date=January 20, 2018}}</ref>
*Specification released in 2003

===EAX 5.0===
EAX 5.0 is supported by [[E-mu 20K]]-based products such as the [[Sound Blaster X-Fi]].
*128 simultaneous voices processable in hardware and up to 4 effects on each
*EAX Voice (processing of microphone input signal)
*EAX PurePath (EAX Sound effects can originate from one speaker only)
*Environment FlexiFX (four available effects slots per channel)
*EAX MacroFX (realistic positional effects at close range)
*Environment Occlusion (sound from adjacent environments can pass through walls)
*Specification released in 2005

===Future development===
In Creative's [[OpenAL]] 1.1 specification, an alternative software system for 3D sound which Creative made, EAX should be considered deprecated as a developer interface. New development should use OpenAL's EFX interface, which emulates all previous EAX functionality and is more tightly coupled with the overall OpenAL framework.<ref>[http://www.blueripplesound.com/index.php?target=games 'OpenAL, EAX and EFX' section explains 'EAX' vs 'EFX']</ref>

Creative stopped updating OpenAL also, although an open source version, OpenAL Soft is still actively maintained.