alsaloop.1 (5000B)
1 .TH ALSALOOP 1 "5 Aug 2010" 2 .SH NAME 3 alsaloop \- command\-line PCM loopback 4 .SH SYNOPSIS 5 \fBalsaloop\fP [\fI\-option\fP] [\fIcmd\fP] 6 .SH DESCRIPTION 7 8 \fBalsaloop\fP allows create a PCM loopback between a PCM capture device 9 and a PCM playback device. 10 11 \fBalsaloop\fP supports multiple soundcards, adaptive clock synchronization, 12 adaptive rate resampling using the samplerate library (if available in 13 the system). Also, mixer controls can be redirected from one card to 14 another (for example Master and PCM). 15 16 .SH OPTIONS 17 18 .TP 19 \fI\-h\fP | \fI\-\-help\fP 20 21 Prints the help information. 22 23 .TP 24 \fI\-g <file>\fP | \fI\-\-config=<file>\fP 25 26 Use given configuration file. The syntax of this file is simple: one line 27 contains the command line options for one job. The '#' means comment and 28 rest of line is ignored. Example: 29 30 # First line \- comment, second line \- first job 31 \-C hw:1,0 \-P hw:0,0 \-t 50000 \-T 1 32 # Third line \- comment, fourth line \- second job 33 \-C hw:1,1 \-P hw:0,1 \-t 40000 \-T 2 34 35 .TP 36 \fI\-d\fP | \fI\-\-daemonize\fP 37 38 Daemonize the main process and use syslog for messages. 39 40 .TP 41 \fI\-P <device>\fP | \fI\-\-pdevice=<device>\fP 42 43 Use given playback device. 44 45 .TP 46 \fI\-C <device>\fP | \fI\-\-cdevice=<device>\fP 47 48 Use given capture device. 49 50 .TP 51 \fI\-X <device>\fP | \fI\-\-pctl=<device>\fP 52 53 Use given CTL device for playback. 54 55 .TP 56 \fI\-Y <device>\fP | \fI\-\-cctl=<device>\fP 57 58 Use given CTL device for capture. 59 60 .TP 61 \fI\-l <latency>\fP | \fI\-\-latency=<frames>\fP 62 63 Requested latency in frames. 64 65 .TP 66 \fI\-t <usec>\fP | \fI\-\-tlatency=<usec>\fP 67 68 Requested latency in usec (1/1000000sec). 69 70 .TP 71 \fI\-f <format>\fP | \fI\-\-format=<format>\fP 72 73 Format specification (usually S16_LE S32_LE). Use \-h to list all formats. 74 Default format is S16_LE. 75 76 .TP 77 \fI\-c <channels>\fP | \fI\-\-channels=<channels>\fP 78 79 Channel count specification. Default value is 2. 80 81 .TP 82 \fI\-c <rate>\fP | \fI\-\-rate=<rate>\fP 83 84 Rate specification. Default value is 48000 (Hz). 85 86 .TP 87 \fI\-n\fP | \fI\-\-resample\fP 88 89 Allow rate resampling using alsa\-lib. 90 91 .TP 92 \fI\-A <converter>\fP | \fI\-\-samplerate=<converter>\fP 93 94 Use libsamplerate and choose a converter: 95 96 0 or sincbest \- best quality 97 1 or sincmedium \- medium quality 98 2 or sincfastest \- lowest quality 99 3 or zerohold \- hold zero samples 100 4 or linear \- worst quality - linear resampling 101 5 or auto \- choose best method 102 103 .TP 104 \fI\-B <size>\fP | \fI\-\-buffer=<size>\fP 105 106 Buffer size in frames. 107 108 .TP 109 \fI\-E <size>\fP | \fI\-\-period=<size>\fP 110 111 Period size in frames. 112 113 .TP 114 \fI\-s <secs>\fP | \fI\-\-seconds=<secs>\fP 115 116 Duration of loop in seconds. 117 118 .TP 119 \fI\-b\fP | \fI\-\-nblock\fP 120 121 Non\-block mode (very early process wakeup). Eats more CPU. 122 123 .TP 124 \fI\-S <mode>\fP | \fI\-\-sync=<mode>\fP 125 126 Sync mode specification for capture to playback stream: 127 0 or none \- do not touch the stream 128 1 or simple \- add or remove samples to keep 129 both streams synchronized 130 2 or captshift \- use driver for the capture device 131 (if supported) to compensate 132 the rate shift 133 3 or playshift \- use driver for the playback device 134 (if supported) to compensate 135 the rate shift 136 4 or samplerate \- use samplerate library to do rate resampling 137 5 or auto \- automatically selects the best method 138 in this order: captshift, playshift, 139 samplerate, simple 140 141 .TP 142 \fI\-T <num>\fP | \fI\-\-thread=<num>\fP 143 144 Thread number (\-1 means create a unique thread). All jobs with same 145 thread numbers are run within one thread. 146 147 .TP 148 \fI\-m <mixid>\fP | \fI\-\-mixer=<midid>\fP 149 150 Redirect mixer control from the playback card to the capture card. Format of 151 \fImixid\fP is SRCID(PLAYBACK)[@DSTID(PLAYBACK)]: 152 153 "name='Master Playback Switch'@name='Another Switch'" 154 "name='PCM Playback Volume'" 155 156 Known attributes: 157 158 name \- control ID name 159 index \- control ID index 160 device \- control ID device 161 subdevice \- control ID subdevice 162 iface \- control ID interface 163 numid \- control ID numid 164 165 .TP 166 \fI\-O <ossmixid>\fP | \fI\-\-ossmixer=<midid>\fP 167 168 Redirect mixer control from the OSS Mixer emulation layer (capture card) 169 to the ALSA layer (capture card). Format of \fIossmixid\fP is 170 ALSAID[,INDEX]@OSSID: 171 172 "Master@VOLUME" 173 "PCM,1@ALTPCM" 174 175 Known OSS attributes: 176 177 VOLUME, BASS, TREBLE, SYNTH, PCM, SPEAKER, LINE, MIC, CD, IMIX, ALTPCM, 178 RECLEV, IGAIN, OGAIN, LINE1, LINE2, LINE3, DIGITAL1, DIGITAL2, DIGITAL3, 179 PHONEIN, PHONEOUT, VIDEO, RADIO, MONITOR 180 181 .TP 182 \fI\-v\fP | \fI\-\-verbose\fP 183 184 Verbose mode. Use multiple times to increase verbosity. 185 186 187 .TP 188 \fI\-U\fP | \fI\-\-xrun\fP 189 190 Verbose xrun profiling. 191 192 .TP 193 \fI\-W <timeout>\fP | \fI\-\-wake=<timeout>\fP 194 195 Set process wake timeout. 196 197 .SH EXAMPLES 198 199 .TP 200 \fBalsaloop \-C hw:0,0 \-P hw:1,0 \-t 50000\fR 201 202 .SH BUGS 203 None known. 204 .SH AUTHOR 205 \fBalsaloop\fP is by Jaroslav Kysela <perex@perex.cz>. 206 This document is by Jaroslav Kysela <perex@perex.cz>.