mirror of
https://github.com/alsa-project/alsa-utils
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513a9c7ad1
- added -W/--wake option to reduce poll time - another try to fix the avail_min parameter for playback - fixed initial silence fill Signed-off-by: Jaroslav Kysela <perex@perex.cz>
206 lines
4.8 KiB
Groff
206 lines
4.8 KiB
Groff
.TH ALSALOOP 1 "5 Aug 2010"
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.SH NAME
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alsaloop \- command-line PCM loopback
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.SH SYNOPSIS
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\fBalsaloop\fP [\fI\-option\fP] [\fIcmd\fP]
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.SH DESCRIPTION
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\fBalsaloop\fP allows create a PCM loopback between a PCM capture device
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and a PCM playback device.
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\fBalsaloop\fP supports multiple soundcards, adaptive clock synchronization,
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adaptive rate resampling using the samplerate library (if available in
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the system). Also, mixer controls can be redirected from one card to
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another (for example Master and PCM).
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.SH OPTIONS
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.TP
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\fI\-h\fP | \fI\-\-help\fP
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Prints the help information.
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.TP
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\fI\-g <file>\fP | \fI\-\-config=<file>\fP
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Use given configuration file. The syntax of this file is simple: one line
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contains the command line options for one job. The '#' means comment and
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rest of line is ignored. Example:
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# First line - comment, second line - first job
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-C hw:1,0 -P hw:0,0 -t 50000 -T 1
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# Third line - comment, fourth line - second job
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-C hw:1,1 -P hw:0,1 -t 40000 -T 2
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.TP
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\fI\-d\fP | \fI\-\-daemonize\fP
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Daemonize the main process and use syslog for messages.
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.TP
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\fI\-P <device>\fP | \fI\-\-pdevice=<device>\fP
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Use given playback device.
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.TP
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\fI\-C <device>\fP | \fI\-\-cdevice=<device>\fP
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Use given capture device.
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.TP
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\fI\-X <device>\fP | \fI\-\-pctl=<device>\fP
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Use given CTL device for playback.
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.TP
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\fI\-Y <device>\fP | \fI\-\-cctl=<device>\fP
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Use given CTL device for capture.
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.TP
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\fI\-l <latency>\fP | \fI\-\-latency=<frames>\fP
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Requested latency in frames.
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.TP
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\fI\-t <usec>\fP | \fI\-\-tlatency=<usec>\fP
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Requested latency in usec (1/1000000sec).
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.TP
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\fI\-f <format>\fP | \fI\-\-format=<format>\fP
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Format specification (usually S16_LE S32_LE). Use -h to list all formats.
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Default format is S16_LE.
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.TP
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\fI\-c <channels>\fP | \fI\-\-channels=<channels>\fP
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Channel count specification. Default value is 2.
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.TP
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\fI\-c <rate>\fP | \fI\-\-rate=<rate>\fP
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Rate specification. Default value is 48000 (Hz).
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.TP
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\fI\-n\fP | \fI\-\-resample\fP
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Allow rate resampling using alsa-lib.
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.TP
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\fI\-A <converter>\fP | \fI\-\-samplerate=<converter>\fP
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Use libsamplerate and choose a converter:
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0 or sincbest - best quality
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1 or sincmedium - medium quality
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2 or sincfastest - lowest quality
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3 or zerohold - hold zero samples
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4 or linear - worst quality - linear resampling
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5 or auto - choose best method
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.TP
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\fI\-B <size>\fP | \fI\-\-buffer=<size>\fP
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Buffer size in frames.
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.TP
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\fI\-E <size>\fP | \fI\-\-period=<size>\fP
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Period size in frames.
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.TP
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\fI\-s <secs>\fP | \fI\-\-seconds=<secs>\fP
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Duration of loop in seconds.
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.TP
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\fI\-b\fP | \fI\-\-nblock\fP
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Non-block mode (very early process wakeup). Eats more CPU.
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.TP
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\fI\-S <mode>\fP | \fI\-\-sync=<mode>\fP
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Sync mode specification for capture to playback stream:
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0 or none - do not touch the stream
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1 or simple - add or remove samples to keep
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both streams synchronized
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2 or captshift - use driver for the capture device
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(if supported) to compensate
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the rate shift
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3 or playshift - use driver for the playback device
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(if supported) to compensate
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the rate shift
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4 or samplerate - use samplerate library to do rate resampling
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5 or auto - automatically selects the best method
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in this order: captshift, playshift,
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samplerate, simple
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.TP
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\fI\-T <num>\fP | \fI\-\-thread=<num>\fP
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Thread number (-1 means create a unique thread). All jobs with same
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thread numbers are run within one thread.
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.TP
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\fI\-m <mixid>\fP | \fI\-\-mixer=<midid>\fP
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Redirect mixer control from the playback card to the capture card. Format of
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\fImixid\fP is SRCID(PLAYBACK)[@DSTID(PLAYBACK)]:
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"name='Master Playback Switch'@name='Another Switch'"
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"name='PCM Playback Volume'"
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Known attributes:
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name - control ID name
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index - control ID index
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device - control ID device
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subdevice - control ID subdevice
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iface - control ID interface
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numid - control ID numid
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.TP
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\fI\-O <ossmixid>\fP | \fI\-\-ossmixer=<midid>\fP
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Redirect mixer control from the OSS Mixer emulation layer (capture card)
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to the ALSA layer (capture card). Format of \fIossmixid\fP is
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ALSAID[,INDEX]@OSSID:
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"Master@VOLUME"
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"PCM,1@ALTPCM"
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Known OSS attributes:
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VOLUME, BASS, TREBLE, SYNTH, PCM, SPEAKER, LINE, MIC, CD, IMIX, ALTPCM,
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RECLEV, IGAIN, OGAIN, LINE1, LINE2, LINE3, DIGITAL1, DIGITAL2, DIGITAL3,
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PHONEIN, PHONEOUT, VIDEO, RADIO, MONITOR
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.TP
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\fI\-v\fP | \fI\-\-verbose\fP
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Verbose mode. Use multiple times to increase verbosity.
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.TP
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\fI\-U\fP | \fI\-\-xrun\fP
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Verbose xrun profiling.
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.TP
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\fI\-W <timeout>\fP | \fI\-\-wake=<timeout>\fP
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Set process wake timeout.
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.SH EXAMPLES
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.TP
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\fBalsaloop \-C hw:0,0 \-P hw:1,0 \-t 50000\fR
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.SH BUGS
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None known.
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.SH AUTHOR
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\fBalsaloop\fP is by Jaroslav Kysela <perex@perex.cz>.
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This document is by Jaroslav Kysela <perex@perex.cz>.
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