mpg123 - play audio MPEG 1.0/2.0 file (layers 1, 2 and 3)

mpg123 [ -tscvqy01m24wC ] [ -b size ] [ -k num ] [ -n num ] [ -f factor ] [ -r rate ] [ -g gain ] [ -a dev ] [ -o s | -o h | -o l ] [ -d n ] [ -h n ] [ -w file ] [ -p proxy ] [ -@ file ] [ -E file ] file ... | URL ... | -

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-1/2 audio bit stream.

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 ``--''.

-t, --test

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

-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 is raw (headerless) linear PCM audio data, 16 bit, host byte order, and stereo or mono, depending on the number of channels in the input files.

-c, --check

Check for filter range violations, and report them for each frame if any occur.

-C, --control

Enable 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.

-v, --verbose

Increase the verbosity level. For example, displays the frame numbers during decoding.

-q, --quiet

Quiet. Suppress diagnostic messages.

-y, --resync

Try to resync and continue decoding if an error occurs in the input file. Also try to recover from certain broken headers. Useful if you have a broken MPEG file, on which mpg123 normally gives up saying `Illegal header'. Be careful: Broken locations in MPEG files might cause sharp, loud pops or clicks, which might damage your speakers if played too loud.

-0, --single0; -1, --single1

Decode only channel 0 (left) or channel 1 (right), respectively. These options are available for stereo MPEG streams only.

-m, --singlemix

Mix both channels. This option is available for stereo MPEG layer-3 streams only. It takes less CPU time than full stereo decoding.

-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.

-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.

-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.

-f factor, --scale factor Change scale factor (default: 32768).

-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.

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

-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.

-o s, --speaker

Direct audio output to the speaker.

-o h, --headphones

Direct audio output to the headphone connector.

-o l, --lineout

Direct audio output to the line-out connector.

-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.

-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.

-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).

--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.

-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.

--stereo

Force stereo output

--reopen

Forces reopen of the audiodevice after ever song

--8bit

Forces 8bit output

-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.

-T, --realtime

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

--aggressive Tries to get higher priority

--title In an xterm, or rxvt, change the window's title to the name of song currently playing.

--help, --longhelp Shows usage instructions

In addition to reading MPEG audio streams from ordinary files and from the standard input, mpg123 supports retrieval of MPEG audio files via the HTTP protocol, which is used in the World Wide Web (WWW). Such files are specified using a so-called URL (universal resource location), 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 lynx(1)) and then play them from there.

If authentication is needed to access the file it can be specified with the -u user:pass.

You can abort mpg123 at any time by pressing Ctrl-C. If you are playing multiple files, this will stop the current file and begin playing the next one. If you want to abort playing immediately instead of skipping to the next file, press Ctrl-C twice in short succession (within about one second).

Note that the result of 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.

lynx(1), sox(1), intro(1)

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 -singlemix 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.

Also note that mpg123 always generates 16 bit stereo data (if one of the -single* options is used, two identical stereo channels are generated). If your hardware requires some other format, for example 8 bit mono, you also have to use a converter such as sox(1).

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 at least 1000 Kbytes.

Known bugs and limitations:

MPEG-2, Layer 1 and 2 not tested. May not work. (Layer 3 should work.)

Free format streams are not supported.

Layer-1 support is not heavily tested.

No CRC error checking is performed.

There is currently no support for audio hardware on DEC Digital Unix, Ultrix and IBM AIX, therefore the -s option has to be used on those platforms.

Main author:

Michael Hipp <hippm@informatik.uni-tuebingen.de>

Uses code (or at least ideas) from:

MPEG Software Simulation Group (Base package)

Philipp Knirsch <phil@mpik-tueb.mpg.de> (DCT36/manual unroll)

Tobias Bading <bading@cs.tu-berlin.de> (subband synthesis)

Jeff Tsay <ctsay@pasteur.eecs.berkeley.edu> (DCT36)

Thomas Woerner (SGI Audio)

Damien Clermonte <clermond@esiee.fr> (HP-UX audio fixes)

Oliver Fromme <oliver.fromme@heim3.tu-clausthal.de>

Internet references:

http://www.mpg123.org