NAME¶
mpg123 - play audio MPEG 1.0/2.0/2.5 stream (layers 1, 2 and 3)
SYNOPSIS¶
mpg123 [
options ]
file ... |
URL ... |
-
DESCRIPTION¶
mpg123 reads one or more
files (or standard input if ``-'' is
specified) 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 standard input. Furthermore,
any name starting with ``http://'' is recognized as URL (see next
section).
OPTIONS¶
mpg123 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.
- -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 once lost
in stream; <0 means search whole stream. If you know there are huge
chunks of invalid data in your files... here is your hammer. Note: Only
since version 1.14 this also increases the amount of junk skipped on
beginning.
- -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 respective 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
specified 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 infinite 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, random 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 operating 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-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 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 optimized 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 module
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 independent 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
- --float
- Forces f32 encoding
- -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 mpg123's longhelp for actually available encodings.
- -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 contain 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 highest 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
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
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 faster sound to your ears or safer
uninterrupted 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 forward
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 currently
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 variables 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 specification. 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 example, 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 terminal
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 ALSO¶
wget(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 output,
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 accompanying the source code.
LICENSE¶
mpg123 is licensed under the GNU Lesser/Library General Public License,
LGPL, version 2.1 .
WEBSITE¶
http://www.mpg123.org
http://sourceforge.net/projects/mpg123