was the original sound system used in Linux and other Unix operating systems, but was deprecated after the 2.5 Linux kernel. Proprietary development was continued by 4Front Technologies, who in July 2007 released sources for OSS under CDDL-1.0 for OpenSolaris and under GPL-2.0-only for Linux. The modern implementation, Open Sound System v4, provides software mixing, resampling, and changing of the volume on a per-application basis; in contrast to PulseAudio, these features are implemented within the kernel. PulseAudio support in OpenIndiana and other illumos distributions relies on the in-kernel OSS implementation ("Boomer"). See also Comparison of free software for audio List of Linux audio software PipeWire PortAudio References External links 2004 software Audio libraries Audio software for Linux Free audio software Free software programmed in C Linux APIs Collabora Software using the LGPL license