Native bindings to the SOFT_direct_channels extension.

This extension allows a multi-channel source to play without virtualized output speakers. By default, OpenAL requires buffer channels to be down-mixed to the output channel configuration, possibly using HRTF or other virtualization techniques to give a sense of speakers that may not be physically present. Sometimes audio tracks are authored with their own spatialization effects, where the AL's virtualization methods can cause a notable decrease in audio quality.

This extension provides a mechanism for applications to specify whether audio should be filtered according to the AL's channel virtualization rules for multi-channel buffers.