![]() Unlike the OpenGL specification, the OpenAL specification includes two subsections of the 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. From a programmer's perspective, very little additional work is required to make this happen in an existing OpenGL-based 3D graphical application. 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. The rendering engine performs all necessary calculations as far as distance attenuation, Doppler effect, etc. Buffers contain audio data in PCM format, either 8- or 16-bit, in either monaural or stereo format. The listener object contains the velocity, position and direction of the listener, and the general gain applied to all sound. A source object contains a pointer to a buffer, the velocity, position and direction of the sound, and the intensity of the sound. The general functionality of OpenAL is encoded in source objects, audio buffers and a single listener. However, OpenAL Soft is a widespread open source alternative. Since 1.1, the implementation by Creative has turned proprietary, with the last releases in free licenses still accessible through the project's Subversion source-code repository. While the OpenAL charter says that there will be an "Architecture Review Board" (ARB) modeled on the OpenGL ARB, no such organization has ever been formed and the OpenAL specification is generally handled and discussed via email on its public mailing list. ![]() It is now hosted (and largely developed) by Creative Technology with on-going support from Apple, Blue Ripple Sound, and free software, open-source enthusiasts. ![]() After the demise of Loki, the project was maintained for a time by the free software/ open source community, and implemented on NVIDIA nForce sound cards and motherboards. OpenAL was originally developed in 2000 by Loki Software to help them in their business of porting Windows games to Linux.
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