Chris Robinson
4cd04f192d
The delay scale is roughly linear with respect to room size, however the density is not linear with room size. The density is calculated by taking the room size cubed, then normalized by some factor. Unnormalizing the density and taking the cube root restores the original room size to use as a delay scale. The patch also alters the delay and all-pass line lengths to be based on a 1 meter room size, so the the room size recovered from the density acts as a direct multiple for the desired target length. Note that the room scale range is unchanged (5m to 50m), so the minimum and maximum delays are the same. It should also be noted that 50m may not be the correct room size for a density value of 1. A density value of 1 corresponds to an environment size of roughly 2.52m when converted from EAX (DENSITY_SCALE should be 16 rather than 125000), but sizes that low result in undesirable resonance in the feedback, indicating other changes are necessary for that to work.
OpenAL soft
master branch CI status : 
OpenAL Soft is an LGPL-licensed, cross-platform, software implementation of the OpenAL 3D audio API. It's forked from the open-sourced Windows version available originally from openal.org's SVN repository (now defunct). OpenAL provides capabilities for playing audio in a virtual 3D environment. Distance attenuation, doppler shift, and directional sound emitters are among the features handled by the API. More advanced effects, including air absorption, occlusion, and environmental reverb, are available through the EFX extension. It also facilitates streaming audio, multi-channel buffers, and audio capture.
More information is available on the official website
Source Install
To install OpenAL Soft, use your favorite shell to go into the build/ directory, and run:
cmake ..
Assuming configuration went well, you can then build it, typically using GNU Make (KDevelop, MSVC, and others are possible depending on your system setup and CMake configuration).
Please Note: Double check that the appropriate backends were detected. Often, complaints of no sound, crashing, and missing devices can be solved by making sure the correct backends are being used. CMake's output will identify which backends were enabled.
For most systems, you will likely want to make sure ALSA, OSS, and PulseAudio were detected (if your target system uses them). For Windows, make sure DirectSound was detected.
Utilities
The source package comes with an informational utility, openal-info, and is built by default. It prints out information provided by the ALC and AL sub- systems, including discovered devices, version information, and extensions.
Configuration
OpenAL Soft can be configured on a per-user and per-system basis. This allows users and sysadmins to control information provided to applications, as well as application-agnostic behavior of the library. See alsoftrc.sample for available settings.
Acknowledgements
Special thanks go to:
- Creative Labs for the original source code this is based off of.
- Christopher Fitzgerald for the current reverb effect implementation, and helping with the low-pass and HRTF filters.
- Christian Borss for the 3D panning code previous versions used as a base.
- Ben Davis for the idea behind a previous version of the click-removal code.
- Richard Furse for helping with my understanding of Ambisonics that is used by the various parts of the library.