ossaudio(3) - NetBSD Manual Pages

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OSSAUDIO(3)             NetBSD Library Functions Manual            OSSAUDIO(3)


NAME
ossaudio -- Open Sound System emulation
LIBRARY
OSS Audio Emulation Library (libossaudio, -lossaudio)
SYNOPSIS
#include <soundcard.h>
DESCRIPTION
The ossaudio library provides an emulation of the Open Sound System audio interface. Use the native audio(4) and mixer(4) interfaces for new programs, and this emulation library only for building code written for other operating systems. Mixer Control Map The following table summarizes the mappings from native interface device names to OSSv3 mixer controls. Native Device Name OSS Mixer Control *.mic SOUND_MIXER_MIC *.line SOUND_MIXER_LINE *.cd SOUND_MIXER_CD *.dac SOUND_MIXER_PCM *.aux SOUND_MIXER_LINE1 *.record SOUND_MIXER_IMIX *.master SOUND_MIXER_VOLUME *.treble SOUND_MIXER_TREBLE *.bass SOUND_MIXER_BASS *.speaker SOUND_MIXER_SPEAKER *.output SOUND_MIXER_OGAIN *.input SOUND_MIXER_IGAIN *.fmsynth SOUND_MIXER_SYNTH *.midi SOUND_MIXER_SYNTH
COMPATIBILITY
The ossaudio interface aims to be compatible with the Open Sound System version 4, as described in: 4Front Technologies, OSS 4.x Programmer's Guide, http://manuals.opensound.com/developer/, 2007.
SEE ALSO
ioctl(2), audio(4), midi(4), mixer(4)
HISTORY
The ossaudio library first appeared in NetBSD 1.3. The Open Sound System up to version 3 was originally the preferred API for writing audio code under Linux until ALSA became the new default in Linux 2.6. It remains the preferred API in FreeBSD and Solaris, and a large body of code exists supporting it.
BUGS
The emulation is incomplete. Some less popular features are not emu- lated (e.g. sync groups), but the essential ioctls used by the major- ity of software are covered. NetBSD AUDIO_MIXER_SET control types cannot be accurately represented in the OSSv4 mixer API, so are treated as enums. Per-stream volume (i.e. SNDCTL_DSP_SETPLAYVOL) is not currently implemented as in OSSv4, and will instead modify the global volume. Applications need to provide samples with the appropriate gain. Linux, FreeBSD, and Solaris provide /dev/dsp and /dev/mixer devices in place of the /dev/audio and /dev/mixer devices this compatibility layer must be accessed through on NetBSD. However, changing this is typically trivial when porting programs. The emulation only covers ioctl(), there are other differences as well. E.g., on a write that would block in non-blocking mode Linux returns EINTR whereas NetBSD 1.3 returns EAGAIN. The emulation uses a #define for ioctl() so some obscure programs can fail to compile. NetBSD 9.99 October 20, 2020 NetBSD 9.99
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