out123 man page

out123 — send raw PCM audio or a waveform pattern to an output device


cat audio.raw | out123 [ options ]

out123 --wave-freq freq1[,freq2,...] [ options ]


out123 reads raw PCM data (in host byte order) from standard input  and plays it on the audio device specified by given options. Alternatively, it can generate periodic signals for playback itself.


out123 options may be either the traditional POSIX one letter options, or the GNU style long options.  POSIX style options start with a single “-”, while GNU long options start with “--”. Option arguments (if needed) follow separated by whitespace (not “=”). Note that some options can be absent from your installation when disabled in the build process.

--name name

Set the name of this instance, possibly used in various places. This sets the client name for JACK output.

-o module, --output module

Select audio output module. You can provide a comma-separated list to use the first one that works.


List the available modules.

-a dev, --audiodevice dev

Specify the audio device to use.  The default is system-dependent (usually /dev/audio or /dev/dsp). Use this option if you have multiple audio devices and the default is not what you want.

-s, --stdout

The audio samples are written to standard output, instead of playing them through the audio device. The output format is the same as the input ... so in this mode, out123 acts like the standard tool cat. This shortcut is equivalent to “-o raw -a -”.

-O file, --outfile

Write raw output into a file (instead of simply redirecting standard output to a file with the shell). This shortcut is equivalent to “-o raw -a file”.

-w file, --wav

Write output as WAV file file , or standard output if - is or the empty string used as file name. You can also use --au and --cdr for AU and CDR format, respectively. Note that WAV/AU writing to non-seekable files or redirected stdout needs some thought. The header is written with the first actual data. The result of decoding nothing to WAV/AU is a file consisting just of the header when it is seekable and really nothing when not (not even a header). Correctly writing data with prophetic headers to stdout is no easy business. This shortcut is equivalent to “-o wav -a file”.

--au file

Write to file in SUN audio format.  If - or the empty string is used as the filename, the AU file is written to stdout. See paragraph about WAV writing for header fun with non-seekable streams. This shortcut is equivalent to “-o au -a file”.

--cdr file

Write to file as a CDR (CD-ROM audio, more correctly CDDA for Compact Disc Digital Audio). If - is or the empty string used as the filename, the CDR file is written to stdout. This shortcut is equivalent to “-o cdr -a file”.

-r rate, --rate rate

Set sample rate in Hz (default: 44100). If this does not match the actual input sampling rate, you get changed pitch. Might be intentional;-)

-c count, --channels count

Set channel count to given value.

-e enc, --encoding enc

Choose output sample encoding. Possible values look like f32 (32-bit floating point), s32 (32-bit signed integer), u32 (32-bit unsigned integer) and the variants with different numbers of bits (s24, u24, s16, u16, s8, u8) and also special variants like ulaw and alaw 8-bit. See the output of out123's longhelp for actually available encodings. Default is s16.

-m, --mono

Set for single-channel audio (default is two channels, stereo).


Select stereo output (2 channels, default).


List known encoding short and long names to standard output.


Check if given format is supported by given driver and device (in command line before encountering this), silently returning 0 as exit value if it is the case.


Print out the short names of encodings supported with the current setup.


If the selected driver and device communicate some default accepted format, print out a command line fragment for out123 setting that format, always in that order: --rate <r> --channels <c> --encoding <e>

-o h, --headphones

Direct audio output to the headphone connector (some hardware only; AIX, HP, SUN).

-o s, --speaker

Direct audio output to the speaker  (some hardware only; AIX, HP, SUN).

-o l, --lineout

Direct audio output to the line-out connector (some hardware only; AIX, HP, SUN).

-b size, --buffer size

Use an audio output buffer of size Kbytes.  This is useful to bypass short periods of heavy system activity, which would normally cause the audio output  to be interrupted.   You should specify a buffer size of at least 1024  (i.e. 1 Mb, which equals about 6 seconds of usual audio data) or more;  less than about 300 does not make much sense.  The default is 0,  which turns buffering off.

--preload fraction

Wait for the buffer to be filled to fraction before starting playback (fraction between 0 and 1). You can tune this prebuffering to either get sound faster to your ears or safer uninterrupted web radio. Default is 0.2 (changed from 1 since version 1.23).

--devbuffer seconds

Set device buffer in seconds; <= 0 means default value. This is the small buffer between the application and the audio backend, possibly directly related to hardware buffers.

--timelimit samples

Set playback time limit in PCM samples if set to a value greater than zero. out123 will stop reading from stdin or playing from the generated wave table after reaching that number of samples.

--wave-freq frequencies

Set wave generator frequency or list of those with comma separation for enabling a generated test signal instead of standard input. Empty values repeat the previous one.

--wave-pat patterns

Set the waveform patterns of the generated waves as comma-separated list. Choices include sine, square, triangle, sawtooth, gauss, pulse, and shot. Empty values repeat the previous one.

--wave-phase phases

Set waveform phase shift(s) as comma-separated list, negative values inverting the pattern in time and empty value repeating the previous.

--wave-limit samples

Set a custom soft limit on the wave table size. Small values cause larger changes in actual frequencies to make whole periods fit.

-t, --test

Test mode.  The audio stream is read, but no output occurs.

-v, --verbose

Increase the verbosity level.

-q, --quiet

Quiet.  Suppress diagnostic messages.


Tries to get higher priority

-T, --realtime

Tries to gain realtime priority.  This option usually requires root privileges to have any effect.

-?, --help

Shows short usage instructions.


Shows long usage instructions.


Print the version string.



Thomas Orgis <maintainer@mpg123.org>, <thomas@orgis.org>

Creator (ancestry of code inside mpg123):

Michael Hipp

Uses code or ideas from various people, see the AUTHORS file accompanying the source code.


out123 is licensed under the GNU Lesser/Library General Public License, LGPL, version 2.1 .




26 May 2016