Editing OpenAL (section)

==API structure and functionality==
The general functionality of OpenAL is encoded in ''source objects'', ''audio buffers'' and a single ''listener''. A source object contains a pointer to a buffer, the velocity, position and direction of the sound, and the intensity of the sound. The listener object contains the velocity, position and direction of the listener, and the general gain applied to all sound.  Buffers contain audio data in [[Pulse-code modulation|PCM]] format, either 8- or [[16-bit]], in either [[monaural]] or [[stereo]] format. The rendering engine performs all necessary calculations for distance attenuation, [[Doppler effect]], etc.

The net result of all of this for the end user is that in a properly written OpenAL application, sounds behave quite naturally as the user moves through the three-dimensional space of the virtual world.  From a programmer's perspective, very little additional work is required to make this happen in an existing OpenGL-based 3D graphical application.

Unlike the OpenGL specification, the OpenAL specification includes two subsections of the [[Application programming interface|API]]: the core consisting of the actual OpenAL function calls, and the ALC (Audio Library Context) API which is used to manage rendering contexts, resource usage and locking in a cross platform manner. There is also an 'ALUT' (Audio Library Utility Toolkit) library that provides higher level 'convenience' functions — exactly analogous to OpenGL's '[[OpenGL Utility Toolkit|GLUT]]'.

In order to provide additional functionality in the future, OpenAL utilizes an extension mechanism. Individual vendors are thereby able to include their own extensions into distributions of OpenAL, commonly for the purpose of exposing additional functionality on their proprietary hardware. Extensions can be promoted to ARB (Architecture Review Board) status, indicating a standard extension which will be maintained for backwards compatibility. ARB extensions have the prospect of being added to the core API after a period of time.

For advanced digital signal processing and hardware-accelerated sound effects, the EFX (Effects Extension) or [[environmental audio extensions]] (EAX) can be used.