Chris Robinson
c6c6e3324d
Last time this attempted to average the HRIRs according to their contribution to a given B-Format channel as if they were loudspeakers, as well as averaging the HRIR delays. The latter part resulted in the loss of the ITD (inter-aural time delay), a key component of HRTF. This time, the HRIRs are averaged similar to above, except instead of averaging the delays, they're applied to the resulting coefficients (for example, a delay of 8 would apply the HRIR starting at the 8th sample of the target HRIR). This does roughly double the IR length, as the largest delay is about 35 samples while the filter is normally 32 samples. However, this is still smaller the original data set IR (which was 256 samples), it also only needs to be applied to 4 channels for first-order ambisonics, rather than the 8-channel cube. So it's doing twice as much work per sample, but only working on half the number of samples. Additionally, since the resulting HRIRs no longer rely on an extra delay line, a more efficient HRTF mixing function can be made that doesn't use one. Such a function can also avoid the per-sample stepping parameters the original uses.
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.