Open AL is a free, cross-platform audio API. The API and coding conventions resemble Open GL, and the library has the best multi-channel 3D positional sound support. The library is, currently, supported by Creative Technology and Apple, with an active community backing. It is an excellent DirectSound alternative.
The library models a collection of audio sources moving in a 3D space that are heard by a single listener somewhere in that space. The basic OpenAL objects are: a listener, a source, and a buffer. There can be a large number of buffers, which contain audio data. Each buffer can be attached to one or more sources, which represent points in the 3D space that emit some sound (audio). There is always one listener object (per audio context), which represents the position where the sources are heard—rendering is done from the perspective of the listener.
The source objects point to an audio buffer, besides the velocity, position, intensity and direction of sound. The audio buffer is the audio data. The listener object contains the velocity, position and direction of the listener (mostly your in-game character). With the help of these three objects, OpenAL helps recreate natural 3D sound in the virtual world (with natural effects such as the Doppler Effect). The library is built with an extensible architecture that makes it very agile and flexible for the future as well.
The API is highly cross-platform and binaries are available for the following platforms: Mac OSX, iPhone, GNU/Linux (OSS/ALSA), BSD, Solaris, IRIX, Windows, Xbox/360, AmigaOS 3.x, and MorphOS. New platform support is not likely in the near future, but this in itself is an exhaustive list.
And if you are wondering what games use Open AL, the following are just some examples: Battlefield 2, Bioshock, Colin McRae: DiRT, Doom 3, Ghost Recon: Advanced Warfighter, Lineage 2, Quake 4, Race Driver: GRID, and Unreal Torunament 2004. The Open AL is also an integral part of the id Tech 3/4/5 and Unreal Engine 2/3 engines.
The library is licensed under LGPL. To work with Open AL, look at the detailed walkthroughs on Open AL by Dev Master. Checkout the Open AL Website.
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Author: Kinshuk Sunil (72 Articles)
Kinshuk Sunil is the founder of the WiSy Blog. An active evangelist for Open Source and a enthusiast Game Designer, Kinshuk focuses on reviewing Softwares, Services and Games here. However, a jack of all trades, Kinshuk can be found talking about almost everything. Catch up with him on twitter @kinshuksunil.
