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SNDCTL(8) System Manager's Manual SNDCTL(8) NAME sndctl -- list and modify soundcard properties SYNOPSIS sndctl [--libxo] [-f device] [-hov] [control[=value] ...] DESCRIPTION The sndctl utility is used to set and display sound card properties, using a control-driven interface, in order to filter and/or set specific proper- ties. The options are as follows: --libxo Generate output via libxo(3) in a selection of different human and machine readable formats. See xo_options(7) for details on command line arguments. -f device Choose a specific audio device (see "FILES"). Userland devices (e.g those registered by virtual_oss(8) can also be selected. -h Print a help message. -o Print values in a format suitable for use inside scripts. -v Run in verbose mode. This option will print all of the device's channel properties. The device controls are as follows: Name Type Read/Write Action name String Read Device name desc String Read Device description status String Read Device status devnode String Read Device node from_user Boolean Read Userland device unit Number Read Device unit caps String Read Device OSS capabitilies bitperfect Boolean Read/Write Bit-perfect mode enabled autoconv Boolean Read/Write Auto-conversions enabled realtime Boolean Read/Write Real-time mode enabled play Group Read Playback properties play.format String Read/Write Playback format play.rate Number Read/Write Playback sample rate play.vchans Boolean Read/Write Playback VCHANs (virtual channels) enabled play.min_rate Number Read Minimum playback sample rate play.max_rate Number Read Maximum playback sample rate play.min_chans Number Read Natively supported minimum playback sample channels play.max_chans Number Read Natively supported maximum playback sample channels play.formats String Read Natively supported playback formats rec Group Read Recording properties rec.format String Read/Write Recording format rec.rate Number Read/Write Recording sample rate rec.vchans Boolean Read/Write Recording VCHANs (virtual channels) enabled rec.min_rate Number Read Minimum recording sample rate rec.max_rate Number Read Maximum recording sample rate rec.min_chans Number Read Natively supported minimum recording sample channels rec.max_chans Number Read Natively supported maximum recording sample channels rec.formats String Read Natively supported recording formats The play.format, play.rate, rec.format and rec.rate controls will be read- only if VCHANs are disabled. The device channel controls are as follows: Name Type Read/Write Action name String Read Channel name parentchan String Read Parent (primary) channel name unit Number Read Channel unit caps String Read Channel OSS capabilities latency Number Read Channel latency format String Read Channel format rate Number Read Channel sample rate pid Number Read PID of process consuming channel proc String Read Name of process consuming channel interrupts Number Read Number of interrupts since channel was opened xruns Number Read Number of playback underruns/recoring overruns feedcount Number Read Number of bytes fed to channel volume Volume Read Channel left-right volume in normalized form (0.00 to 1.00). hwbuf Group Read Hardware buffer properties hwbuf.format String Read Hardware buffer format hwbuf.rate String Read Hardware buffer sample rate hwbuf.size_bytes Number Read Hardware buffer size in bytes hwbuf.size_frames Number Read Hardware buffer size in frames hwbuf.blksz Number Read Hardware buffer block size hwbuf.blkcnt Number Read Hardware buffer block count hwbuf.free Number Read Hardware buffer free space in bytes hwbuf.ready Number Read Hardware buffer ready space in bytes swbuf Group Read Software buffer properties swbuf.format String Read Software buffer format swbuf.rate String Read Software buffer sample rate swbuf.size_bytes Number Read Software buffer size in bytes swbuf.size_frames Number Read Software buffer size in frames swbuf.blksz Number Read Software buffer block size swbuf.blkcnt Number Read Software buffer block count swbuf.free Number Read Software buffer free space in bytes swbuf.ready Number Read Software buffer ready space in bytes feederchain String Read Channel feeder chain FILES /dev/dsp The default audio device. /dev/dspX The audio device file, where X is the unit of the device, for example /dev/dsp0. EXAMPLES Disable auto-conversions and enable realtime mode to get as low latencies as possible: $ sndctl autoconv=0 realtime=1 Set the playback sample format to 2-channel signed 24-bit low endian, and sample rate to 48000 Hz: $ sndctl play.format=s24le:2.0 play.rate=48000 List the PIDs and process names of all channels for /dev/dsp1: $ sndctl -f /dev/dsp1 pid proc Dump /dev/dsp0 information to a file and retrieve back later: $ sndctl -f /dev/dsp0 -o > info ... $ sndctl -f /dev/dsp0 `cat info` SEE ALSO sndstat(4), sound(4), xo_options(7), mixer(8), sysctl(8) AUTHORS The sndctl utility was implemented by Christos Margiolis <chris- tos@FreeBSD.org> under sponsorship from the FreeBSD Foundation. FreeBSD ports 15.quarterly December 2, 2025 SNDCTL(8)
NAME | SYNOPSIS | DESCRIPTION | FILES | EXAMPLES | SEE ALSO | AUTHORS
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