Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
ALSALOOP(1)		    General Commands Manual		   ALSALOOP(1)

NAME
       alsaloop	- command-line PCM loopback

SYNOPSIS
       alsaloop	[-option] [cmd]

DESCRIPTION
       alsaloop	 allows	create a PCM loopback between a	PCM capture device and
       a PCM playback device.

       alsaloop	supports multiple soundcards, adaptive clock  synchronization,
       adaptive	 rate resampling using the samplerate library (if available in
       the system). Also, mixer	controls can be	redirected from	 one  card  to
       another (for example Master and PCM).

OPTIONS
       -h | --help

	      Prints the help information.

       -g _file_ | --config=_file_

	      Use given	configuration file. The	syntax of this file is simple:
	      one line contains	the command line options for one job. The  '#'
	      means comment and	rest of	line is	ignored. Example:

		# First	line - comment,	second line - first job
		-C hw:1,0 -P hw:0,0 -t 50000 -T	1
		# Third	line - comment,	fourth line - second job
		-C hw:1,1 -P hw:0,1 -t 40000 -T	2

       -d | --daemonize

	      Daemonize	the main process and use syslog	for messages.

       -P _device_ | --pdevice=_device_

	      Use given	playback device.

       -C _device_ | --cdevice=_device_

	      Use given	capture	device.

       -X _device_ | --pctl=_device_

	      Use given	CTL device for playback.

       -Y _device_ | --cctl=_device_

	      Use given	CTL device for capture.

       -l _latency_ | --latency=_frames_

	      Requested	latency	in frames.

       -t _usec_ | --tlatency=_usec_

	      Requested	latency	in usec	(1/1000000sec).

       -f _format_ | --format=_format_

	      Format specification (usually S16_LE S32_LE). Use	-h to list all
	      formats.	Default	format is S16_LE.

       -c _channels_ | --channels=_channels_

	      Channel count specification. Default value is 2.

       -c _rate_ | --rate=_rate_

	      Rate specification. Default value	is 48000 (Hz).

       -n | --resample

	      Allow rate resampling using alsa-lib.

       -A _converter_ |	--samplerate=_converter_

	      Use libsamplerate	and choose a converter:

		0 or sincbest	  - best quality
		1 or sincmedium	  - medium quality
		2 or sincfastest  - lowest quality
		3 or zerohold	  - hold zero samples
		4 or linear	  - worst quality - linear resampling
		5 or auto	  - choose best	method

       -B _size_ | --buffer=_size_

	      Buffer size in frames.

       -E _size_ | --period=_size_

	      Period size in frames.

       -s _secs_ | --seconds=_secs_

	      Duration of loop in seconds.

       -b | --nblock

	      Non-block	mode (very early process wakeup). Eats more CPU.

       -S _mode_ | --sync=_mode_

	      Sync mode	specification for capture to playback stream:
		0 or none	- do not touch the stream
		1 or simple	- add or remove	samples	to keep
				  both streams synchronized
		2 or captshift	- use driver for the capture device
				  (if supported) to compensate
				  the rate shift
		3 or playshift	- use driver for the playback device
				  (if supported) to compensate
				  the rate shift
		4 or samplerate	- use samplerate library to do rate resampling
		5 or auto	- automatically	selects	the best method
				  in this order: captshift, playshift,
				  samplerate, simple

       -T _num_	| --thread=_num_

	      Thread number (-1	means create a unique thread). All  jobs  with
	      same thread numbers are run within one thread.

       -m _mixid_ | --mixer=_midid_

	      Redirect	mixer  control	from  the playback card	to the capture
	      card. Format of mixid is SRCID(PLAYBACK)[@DSTID(PLAYBACK)]:

		"name='Master Playback Switch'@name='Another Switch'"
		"name='PCM Playback Volume'"

	      Known attributes:

		name	  - control ID name
		index	  - control ID index
		device	  - control ID device
		subdevice - control ID subdevice
		iface	  - control ID interface
		numid	  - control ID numid

       -O _ossmixid_ | --ossmixer=_midid_

	      Redirect mixer control from the OSS Mixer	emulation layer	 (cap-
	      ture  card) to the ALSA layer (capture card). Format of ossmixid
	      is ALSAID[,INDEX]@OSSID:

		"Master@VOLUME"
		"PCM,1@ALTPCM"

	      Known OSS	attributes:

		VOLUME,	BASS, TREBLE, SYNTH,  PCM,  SPEAKER,  LINE,  MIC,  CD,
	      IMIX, ALTPCM,
		RECLEV,	IGAIN, OGAIN, LINE1, LINE2, LINE3, DIGITAL1, DIGITAL2,
	      DIGITAL3,
		PHONEIN, PHONEOUT, VIDEO, RADIO, MONITOR

       -v | --verbose

	      Verbose mode. Use	multiple times to increase verbosity.

       -U | --xrun

	      Verbose xrun profiling.

       -W _timeout_ | --wake=_timeout_

	      Set process wake timeout.

EXAMPLES
       alsaloop	-C hw:0,0 -P hw:1,0 -t 50000

BUGS
       None known.

AUTHOR
       alsaloop	is by Jaroslav Kysela <perex@perex.cz>.	 This document	is  by
       Jaroslav	Kysela <perex@perex.cz>.

				  5 Aug	2010			   ALSALOOP(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | BUGS | AUTHOR

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=alsaloop&sektion=1&manpath=FreeBSD+12.1-RELEASE+and+Ports>

home | help