3DsoundSurge Special Feature: Creative's EAGLE

The EAGLE has landed

One of the technologies central to Creative's Environmental Audio is EAX. EAX is the name given to Creative’s Environmental Audio extensions to Microsoft’s Direct Sound Application Programmer Interface (API). While Direct Sound allows game developers to place, and move, sounds in a 3D space, these extensions enable the developer to define the audio characteristics of the room that the player is in. For example – if the player is exploring a dark cave, they’ll hear the reverb and echoes change as they move from a narrow passageway to a huge, underground chamber. Fore more on EAX 1.0 you can check out our Gamer's Guide to EAX.

Sound design for games can be thought of as being very similar to sound design for movies. It’s all for effect. Anyone who has ever fired a handgun will tell you the sound is little more than a loud "pop," which would lack the drama required for a big screen action flick. This is where the sound design team comes in and will use every tool at their disposal to make sure each gunshot has the dramatic impact the scene requires. As in game development, artists are creating a unique experience, not emulating reality. EAX can be viewed as an enabling technology for immersive audio creation, and EAGLE is a sound design tool designed specifically for sound designers to aid them in this quest.

Simply stated, EAGLE is a 3D Audio Modeling Tool. Functionally, EAGLE can be broken down into a variety of sections. The first is a comprehensive Environment Editing Toolkit that will allow the sound designer to easily create and edit new environments and obstacle behavior models. In this mode, the user is presented with a menu of sliders controlling a number of EAX reverb parameters. As the values for these parameters are changed, the user is able to evaluate his work in real time, and then save his settings as a unique Environment Model. One interesting note is that any number of Environments may be opened at one time, so the user can quickly and easily listen to how different Environments sound together. This is invaluable in helping to make sure that a new game has a consistent "feel" to the audio. Further down, the Obstacle Behavior modeling section allows the user to control how sound sources interact with different game conditions. For example, an Obstacle Behavior Model will let the sound designer determine what an opponent’s footsteps will sound like when they run behind a barricade, while an Occlusion Behavior Model will mute the sound in an appropriate fashion when the opponent runs into another room and shuts the door behind him.

EAGLE also contains a set of source property tools which afford the user microscopic control over the behavior of each individual sound effect. The value of these controls becomes very obvious when one considers this scenario: a helicopter flying, far off in the distance will be audible for miles, whereas the sound of the wind chimes outside the door may only be heard from less than ten feet away. The difference here is not the sound effect itself, but rather how the audio designer handles it. Once again, EAGLE provides this control in an intuitive manner.

Another set of controls within EAGLE allows the sound designer to import actual game level maps in order to apply the newly created Environments. In order to support the many different 3D data formats and in house proprietary formats, EAGLE exposes a plug-in architecture that will allow development houses to write their own import components.

Once these maps are imported, the user is greeted with a workspace consisting of four main windows, and a number of Environment Partition Brush controls. Each of the four main windows provides a unique view of the map, including a top, front and side view, as well as a real time 3D "first person" view. When editing in this mode, the audio designer is able to divide the map into different audio subspaces, and to quickly, and easily apply environment and material properties to these subspaces (rooms and areas of the map) . It is then possible to launch the game from directly within EAGLE so that the user can check his work, and make any changes within a single application. These effects are then applied to sounds interactively during game play. EAGLE also allows the designer to drop sounds into the level geometry for auditioning purposes and real-time 3D mixing, thus delivering total artistic control over the audio experience. EAGLE offers full support for EAX 2.0 and will offer support for future versions of EAX as it is extended in the future with new functionality and effects. EAGLE can also be modified to allow for quick and easy Environmental Audio support on a variety of platforms beyond DirectX including the forthcoming Open AL API.

Creative's intent with EAGLE is to allows the game programmer and the audio designer to work together in ways that they never have before. Instead of relying on the level programmer to make crucial decisions about reverb decay times, high frequency roll off factors and air absorption ratios, the level designer can concentrate on making better levels. Once these levels have been built, they can be handed off to the audio team where the benefits of EAGLE can be utilized to work quickly and add Environmental Audio in an artistic manner.

The EAGLE 3D audio modeling tool is now being freely distributed to enhance and promote EAX (Environmental Audio Extensions) implementation in future game titles and will soon be made available for free download at:

Look for more from us on EAGLE, EAX 2.0, A3D 3.0 and other APIs through out the year.