mpg123(1)mpg123(1)NAMEmpg123 - play audio MPEG 1.0/2.0/2.5 stream (layers 1, 2 and 3)
SYNOPSISmpg123 [ options ] file ... | URL ... | -
DESCRIPTIONmpg123 reads one or more files (or standard input if ``-'' is speci‐
fied) or URLs and plays them on the audio device (default) or outputs
them to stdout. file/URL is assumed to be an MPEG audio bit stream.
OPERANDS
The following operands are supported:
file(s) The path name(s) of one or more input files. They must be
valid MPEG-1.0/2.0/2.5 audio layer 1, 2 or 3 bit streams. If a
dash ``-'' is specified, MPEG data will be read from the stan‐
dard input. Furthermore, any name starting with ``http://'' is
recognized as URL (see next section).
OPTIONSmpg123 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.
INPUT OPTIONS-k num, --skip num
Skip first num frames. By default the decoding starts at the
first frame.
-n num, --frames num
Decode only num frames. By default the complete stream is
decoded.
--fuzzy
Enable fuzzy seeks (guessing byte offsets or using approximate
seek points from Xing TOC). Without that, seeks need a first
scan through the file before they can jump at positions. You
can decide here: sample-accurate operation with gapless features
or faster (fuzzy) seeking.
-y, --no-resync
Do NOT try to resync and continue decoding if an error occurs in
the input file. Normally, mpg123 tries to keep the playback
alive at all costs, including skipping invalid material and
searching new header when something goes wrong. With this
switch you can make it bail out on data errors (and perhaps
spare your ears a bad time). Note that this switch has been
renamed from --resync. The old name still works, but is not
advertised or recommened to use (subject to removal in future).
--resync-limit bytes
Set number of bytes to search for valid MPEG data; <0 means
search whole stream. If you know there are huge chunks of
invalid data in your files... here is your hammer.
-p URL | none, --proxy URL | none
The specified proxy will be used for HTTP requests. It should
be specified as full URL (``http://host.domain:port/''), but the
``http://'' prefix, the port number and the trailing slash are
optional (the default port is 80). Specifying none means not to
use any proxy, and to retrieve files directly from the respec‐
tive servers. See also the ``HTTP SUPPORT'' section.
-u auth, --auth auth
HTTP authentication to use when recieving files via HTTP. The
format used is user:password.
-@ file, --list file
Read filenames and/or URLs of MPEG audio streams from the speci‐
fied file in addition to the ones specified on the command line
(if any). Note that file can be either an ordinary file, a dash
``-'' to indicate that a list of filenames/URLs is to be read
from the standard input, or an URL pointing to a an appropriate
list file. Note: only one -@ option can be used (if more than
one is specified, only the last one will be recognized).
-l n, --listentry n
Of the playlist, play specified entry only. n is the number of
entry starting at 1. A value of 0 is the default and means
playling the whole list, a negative value means showing of the
list of titles with their numbers...
--loop times
for looping track(s) a certain number of times, < 0 means infi‐
nite loop (not with --random!).
--keep-open
For remote control mode: Keep loaded file open after reaching
end.
--timeout seconds
Timeout in (integer) seconds before declaring a stream dead (if
<= 0, wait forever).
-z, --shuffle
Shuffle play. Randomly shuffles the order of files specified on
the command line, or in the list file.
-Z, --random
Continuous random play. Keeps picking a random file from the
command line or the play list. Unlike shuffle play above, ran‐
dom play never ends, and plays individual songs more than once.
--no-icy-meta
Do not accept ICY meta data.
-i, --index
Index / scan through the track before playback. This fills the
index table for seeking (if enabled in libmpg123) and may make
the operating system cache the file contents for smoother oper‐
ating on playback.
--index-size size
Set the number of entries in the seek frame index table.
--preframes num
Set the number of frames to be read as lead-in before a seeked-
to position. This serves to fill the layer 3 bit reservoir,
which is needed to faithfully reproduce a certain sample at a
certain position. Note that for layer 3, a minimum of 1 is
enforced (because of frame overlap), and for layer 1 and 2, this
is limited to 2 (no bit reservoir in that case, but engine spin-
up anyway).
OUTPUT and PROCESSING OPTIONS-o module, --output module
Select audio output module. You can provide a comma-separated
list to use the first one that works.
--list-modules
List the available modules.
-a dev, --audiodevice dev
Specify the audio device to use. The default is system-depen‐
dent (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 decoded audio samples are written to standard output,
instead of playing them through the audio device. This option
must be used if your audio hardware is not supported by mpg123.
The output format per default is raw (headerless) linear PCM
audio data, 16 bit, stereo, host byte order (you can force mono
or 8bit).
-O file, --outfile
Write raw output into a file (instead of simply redirecting
standard output to a file with the shell).
-w file, --wav
Write output as WAV file. This will cause the MPEG stream to be
decoded and saved as file file , or standard output if - is used
as file name. You can also use --au and --cdr for AU and CDR
format, respectively.
--au file
Does not play the MPEG file but writes it to file in SUN audio
format. If - is used as the filename, the AU file is written to
stdout.
--cdr file
Does not play the MPEG file but writes it to file as a CDR file.
If - is used as the filename, the CDR file is written to stdout.
--reopen
Forces reopen of the audiodevice after ever song
--cpu decoder-type
Selects a certain decoder (optimized for specific CPU), for
example i586 or MMX. The list of available decoders can vary;
depending on the build and what your CPU supports. This options
is only availabe when the build actually includes several opti‐
mized decoders.
--test-cpu
Tests your CPU and prints a list of possible choices for --cpu.
--list-cpu
Lists all available decoder choices, regardless of support by
your CPU.
-g gain, --gain gain
[DEPRECATED] Set audio hardware output gain (default: don't
change). The unit of the gain value is hardware and output mod‐
ule dependent. (This parameter is only provided for backwards
compatibility and may be removed in the future without prior
notice. Use the audio player for playing and a mixer app for
mixing, UNIX style!)
-f factor, --scale factor
Change scale factor (default: 32768).
--rva-mix, --rva-radio
Enable RVA (relative volume adjustment) using the values stored
for ReplayGain radio mode / mix mode with all tracks roughly
equal loudness. The first valid information found in ID3V2 Tags
(Comment named RVA or the RVA2 frame) or ReplayGain header in
Lame/Info Tag is used.
--rva-album, --rva-audiophile
Enable RVA (relative volume adjustment) using the values stored
for ReplayGain audiophile mode / album mode with usually the
effect of adjusting album loudness but keeping relative loudness
inside album. The first valid information found in ID3V2 Tags
(Comment named RVA_ALBUM or the RVA2 frame) or ReplayGain header
in Lame/Info Tag is used.
-0, --single0; -1, --single1
Decode only channel 0 (left) or channel 1 (right), respectively.
These options are available for stereo MPEG streams only.
-m, --mono, --mix, --singlemix
Mix both channels / decode mono. It takes less CPU time than
full stereo decoding.
--stereo
Force stereo output
-r rate, --rate rate
Set sample rate (default: automatic). You may want to change
this if you need a constant bitrate independed of the mpeg
stream rate. mpg123 automagically converts the rate. You should
then combine this with --stereo or --mono.
-2, --2to1; -4, --4to1
Performs a downsampling of ratio 2:1 (22 kHz) or 4:1 (11 kHz) on
the output stream, respectively. Saves some CPU cycles, but at
least the 4:1 ratio sounds ugly.
--pitch value
Set hardware pitch (speedup/down, 0 is neutral; 0.05 is 5%).
This changes the output sampling rate, so it only works in the
range your audio system/hardware supports.
--8bit Forces 8bit output
-d n, --doublespeed n
Only play every n'th frame. This will cause the MPEG stream to
be played n times faster, which can be used for special effects.
Can also be combined with the --halfspeed option to play 3 out
of 4 frames etc. Don't expect great sound quality when using
this option.
-h n, --halfspeed n
Play each frame n times. This will cause the MPEG stream to be
played at 1/n'th speed (n times slower), which can be used for
special effects. Can also be combined with the --doublespeed
option to double every third frame or things like that. Don't
expect great sound quality when using this option.
-E file, --equalizer
Enables equalization, taken from file. The file needs to con‐
tain 32 lines of data, additional comment lines may be prefixed
with #. Each data line consists of two floating-point entries,
separated by whitespace. They specify the multipliers for left
and right channel of a certain frequency band, respectively.
The first line corresponds to the lowest, the 32nd to the high‐
est frequency band. Note that you can control the equalizer
interactively with the generic control interface.
--gapless
Enable code that cuts (junk) samples at beginning and end of
tracks, enabling gapless transitions between MPEG files when
encoder padding and codec delays would prevent it. This is
enabled per default beginning with mpg123 version 1.0.0 .
--no-gapless
Disable the gapless code. That gives you MP3 decodings that
include encoder delay and padding plus mpg123's decoder delay.
-D n, --delay n
Insert a delay of n seconds before each track.
-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 nor‐
mally 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 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 pre‐
buffering to either get faster sound to your ears or safer unin‐
terrupted web radio. Default is 1 (wait for full buffer before
playback).
--smooth
Keep buffer over track boundaries -- meaning, do not empty the
buffer between tracks for possibly some added smoothness.
MISC OPTIONS-t, --test
Test mode. The audio stream is decoded, but no output occurs.
-c, --check
Check for filter range violations (clipping), and report them
for each frame if any occur.
-v, --verbose
Increase the verbosity level. For example, displays the frame
numbers during decoding.
-q, --quiet
Quiet. Suppress diagnostic messages.
-C, --control
Enable terminal control keys. By default use 's' or the space
bar to stop/restart (pause, unpause) playback, 'f' to jump for‐
ward to the next song, 'b' to jump back to the beginning of the
song, ',' to rewind, '.' to fast forward, and 'q' to quit. Type
'h' for a full list of available controls.
--title
In an xterm, or rxvt (compatible, TERM environment variable is
examined), change the window's title to the name of song cur‐
rently playing.
--long-tag
Display ID3 tag info always in long format with one line per
item (artist, title, ...)
--utf8 Regardless of environment, print metadata in UTF-8 (otherwise,
when not using UTF-8 locale, you'll get ASCII stripdown).
-R, --remote
Activate generic control interface. mpg123 will then read and
execute commands from stdin. Basic usage is ``load <filename> ''
to play some file and the obvious ``pause'', ``command. ``jump
<frame>'' will jump/seek to a given point (MPEG frame number).
Issue ``help'' to get a full list of commands and syntax.
--remote-err
Print responses for generic control mode to standard error, not
standard out. This is automatically triggered when using -s .
--fifo path
Create a fifo / named pipe on the given path and use that for
reading commands instead of standard input.
--aggressive
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.
--longhelp
Shows long usage instructions.
--version
Print the version string.
HTTP SUPPORT
In addition to reading MPEG audio streams from ordinary files and from
the standard input, mpg123 supports retrieval of MPEG audio files or
playlists via the HTTP protocol, which is used in the World Wide Web
(WWW). Such files are specified using a so-called URL, which starts
with ``http://''. When a file with that prefix is encountered, mpg123
attempts to open an HTTP connection to the server in order to retrieve
that file to decode and play it.
It is often useful to retrieve files through a WWW cache or so-called
proxy. To accomplish this, mpg123 examines the environment for vari‐
ables named MP3_HTTP_PROXY, http_proxy and HTTP_PROXY, in this order.
The value of the first one that is set will be used as proxy specifica‐
tion. To override this, you can use the -p command line option (see
the ``OPTIONS'' section). Specifying -p none will enforce contacting
the server directly without using any proxy, even if one of the above
environment variables is set.
Note that, in order to play MPEG audio files from a WWW server, it is
necessary that the connection to that server is fast enough. For exam‐
ple, a 128 kbit/s MPEG file requires the network connection to be at
least 128 kbit/s (16 kbyte/s) plus protocol overhead. If you suffer
from short network outages, you should try the -b option (buffer) to
bypass such outages. If your network connection is generally not fast
enough to retrieve MPEG audio files in realtime, you can first download
the files to your local harddisk (e.g. using wget(1)) and then play
them from there.
If authentication is needed to access the file it can be specified with
the -u user:pass.
INTERRUPT
When in terminal control mode, you can quit via pressing the q key,
while any time you can abort mpg123 by pressing Ctrl-C. If not in ter‐
minal control mode, this will skip to the next file (if any). If you
want to abort playing immediately in that case, press Ctrl-C twice in
short succession (within about one second).
Note that the result of quitting mpg123 pressing Ctrl-C might not be
audible immediately, due to audio data buffering in the audio device.
This delay is system dependent, but it is usually not more than one or
two seconds.
SEE ALSOwget(1), sox(1),
NOTES
MPEG audio decoding requires a good deal of CPU performance, especially
layer-3. To decode it in realtime, you should have at least an
i486DX4, Pentium, Alpha, SuperSparc or equivalent processor. You can
also use the -m option to decode mono only, which reduces the CPU load
somewhat for layer-3 streams. See also the -2 and -4 options.
If everything else fails, use the -s option to decode to standard out‐
put, direct it into a file and then use an appropriate utility to play
that file. You might have to use a tool such as sox(1) to convert the
output to an audio format suitable for your audio player.
If your system is generally fast enough to decode in realtime, but
there are sometimes periods of heavy system load (such as cronjobs,
users logging in remotely, starting of ``big'' programs etc.) causing
the audio output to be interrupted, then you should use the -b option
to use a buffer of reasonable size (at least 1000 Kbytes).
BUGS
Mostly MPEG-1 layer 2 and 3 are tested in real life. Please report any
issues and provide test files to help fixing them.
Free format streams are not supported, but they could be (there is some
code).
No CRC error checking is performed.
Some platforms lack audio hardware support; you may be able to use the
-s switch to feed the decoded data to a program that can play it on
your audio device. Notably, this includes Tru64 with MME, but you
should be able to install and use OSS there (it perhaps will perform
better as MME would anyway).
AUTHORS
Maintainers:
Thomas Orgis <maintainer@mpg123.org>, <thomas@orgis.org>
Nicholas J. Humfrey
Creator:
Michael Hipp
Uses code or ideas from various people, see the AUTHORS file accompany‐
ing the source code.
LICENSEmpg123 is licensed under the GNU Lesser/Library General Public License,
LGPL, version 2.1 .
WEBSITE
http://www.mpg123.org
http://sourceforge.net/projects/mpg123
31 Jan 2008 mpg123(1)
