mpg123(1)

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 ``='').

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.

-y, --resync
    Do NOT try to resync and continuing 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 may either disappear in future or its meaning be revised since it now does the opposite of what it suggests.

-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...

-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.

OUTPUT and PROCESSING OPTIONS

-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).

-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

-g gain, --gain gain
    Set audio hardware output gain (default: don't change).

-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.

--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 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.

-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.

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' to stop, 'p' to pause, '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.

--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, ...)

-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 stderr, not stdout. That is extremely useful when you want to grab the audio via -s -s )

--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 a 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

Main author:
    Michael Hipp

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

LICENSE
The majority of 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