An Audio Library Built for 3D Sound
OpenAL (Open Audio Library) is a cross-platform audio application programming interface designed for the efficient processing of multichannel three-dimensional audio. Its API style and rules were deliberately modeled on OpenGL, according to the Turkish Wikipedia article on the subject. The library’s early releases were open source, though later versions became proprietary.
Origins and Maintenance
OpenAL was first developed in 2000 by Loki Software to help port Windows games to Linux. After Loki Software closed, the project was continued by the free software and open source community, where it was adapted for NVIDIA nForce sound cards and motherboards. The library is now developed by Creative Technology with support from Apple, Blue Ripple Sound, and free software enthusiasts.
Although the main OpenAL contract states that an Architecture Evaluation Board would follow the model of the OpenGL ARB, no such organization was ever established. Instead, OpenAL features are generally discussed and debated on a public mailing list.
The Proprietary Split and Free Alternatives
From version 1.1 onward, the Creative adaptation became a proprietary project. The last free-licensed version of this adaptation remains accessible through the project’s Subversion source code repository. A widely used and current free alternative exists under the name OpenAL Soft.
Supported Platforms
The API is available across numerous operating systems, including Android, BSD, iOS, IRIX, Linux, Mac OS X, Microsoft Windows, MorphOS, OpenBSD, Solaris, QNX, AROS, AmigaOS, Bada, BlackBerry 10, BlackBerry PlayBook, and Windows. It also supports game consoles such as GameCube, PlayStation 2, PlayStation 3, Xbox, Xbox 360, Wii, and PlayStation Portable.
Implementations and Their Capabilities
OpenAL Sample Implementation (OpenAL SI) was the first version developed by Loki and is no longer maintained. OpenAL Soft is an LGPL-licensed, cross-platform software implementation. It was conceived both as a compatible update for the now-defunct OpenAL Sample Implementation and as a free alternative to the now-proprietary OpenAL. OpenAL Soft supports single-channel, stereo, 4-channel, 5.1, 6.1, and 7.1 outputs.
AeonWave-OpenAL is an LGPL-licensed OpenAL emulation layer that benefits from hardware acceleration provided by the AeonWave 4D-audio library. Using the AeonWave library, this implementation offers HRTF support as well as three-dimensional surround sound support for up to eight speakers.
Rapture3D OpenAL is a proprietary, commercial software implementation developed by Blue Ripple Sound for Windows only. It was designed as a high-performance alternative to other implementations.
Applications
According to Creative Labs, various games use OpenAL. Among other applications, Blender uses OpenAL for its built-in game engine, and 3DMark uses it as a performance measurement and benchmarking tool for gamers. The Dolphin emulator, which emulates GameCube and Wii, relies on the library. The Vanda Engine uses OpenAL 1.1 to simulate 2D and 3D audio.
This explanation is adapted from Wikipedia and is available under CC BY-SA 4.0.
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