     mpg123(1)                                                         mpg123(1)
                                     29 Feb 2016

     NAME
          mpg123 - play audio MPEG 1.0/2.0/2.5 stream (layers 1, 2 and 3)

     SYNOPSIS
          mpg123 [ options ] file-or-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.

     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

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               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.

          --ignore-mime
               Ignore MIME types given by HTTP server. If you know better and
               want mpg123 to decode something the server thinks is image/png,
               then just do it.

          --no-seekbuffer
               Disable the default micro-buffering of non-seekable streams that
               gives the parser a safer footing.

          -@ 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...

          --continue
               Enable playlist continuation mode. This changes frame skipping to
               apply only to the first track and also continues to play

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               following tracks in playlist after the selected one. Also, the
               option to play a number of frames only applies to the whole
               playlist. Basically, this tries to treat the playlist more like
               one big stream (like, an audio book).  The current track number
               in list (1-based) and frame number (0-based) are printed at exit
               (useful if you interrupted playback and want to continue later).
               Note that the continuation info is printed to standard output
               unless the switch for piping audio data to standard out is used.
               Also, it really makes sense to work with actual playlist files
               instead of lists of file names as arguments, to keep track
               positions consistent.

          --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

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                                     29 Feb 2016

               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. Note that WAV/AU writing to non-seekable
               files, or redirected stdout, needs some thought. Since 1.16.0,
               the logic changed to writing the header with the first actual
               data. This avoids spurious WAV headers in a pipe, for example.
               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.

          --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. See paragraph about WAV writing for header fun with non-
               seekable streams.

          --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.

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                                     29 Feb 2016

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

          -m, --mono, --mix,
               Mix both channels / decode mono. It takes less CPU time than full
               stereo decoding.

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                                     29 Feb 2016

          --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,
               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,

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     mpg123(1)                                                         mpg123(1)
                                     29 Feb 2016

               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.

          --no-infoframe
               Do not parse the Xing/Lame/VBR/Info frame, decode it instead just
               like a stupid old MP3 hardware player.  This implies disabling of
               gapless playback as the necessary information is in said metadata
               frame.

          -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 0.2 (wait for 20 % of buffer

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               to be full, changed from 1 in 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.

          --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. This is enabled automatically if a
               terminal is detected.  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.

          --no-control
               Disable terminal control even if terminal is detected.

          --title
               In an xterm, rxvt, screen, iris-ansi (compatible, TERM
               environment variable is examined), change the window's title to
               the name of song currently playing.

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

          --long-tag
               Display ID3 tag info always in long format with one line per item
               (artist, title, ...)

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          --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 N.

          --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

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          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.

     PLAYBACK STATUS LINE
          In verbose mode, mpg123 updates a line with various information
          centering around the current playback position. On any decent
          terminal, the line also works as a progress bar in the current file by
          reversing video for a fraction of the line according to the current
          position. An example for a full line is this:

               > 0291+0955  00:01.68+00:28.22 [00:05.30] mix 100=085 192 kb/s
          576 B acc   18 clip p+0.014

          The information consists of, in order:

          >    single-character playback state (``>'' for playing, ``='' for
               pausing/looping, ``_'' for stopped)

          0291+0955
               current frame offset and number of remaining frames after the
               plus sign

          00:01.68+00:28.22
               current position from and remaining time in human terms (hours,
               minutes, seconds)

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                                     29 Feb 2016

          [00:05.30]
               fill of the output buffer in terms of playback time, if the
               buffer is enabled

          mix  selected RVA mode (possible values: mix, alb (album), and ---
               (neutral, off))

          100=085
               set volume and the RVA-modified effective volume after the equal
               sign

          192 kb/s
               current bitrate

          576 B
               size of current frame in bytes

          acc  if positions are accurate, possible values are ``acc'' for
               accurate positions or ``fuz'' for fuzzy (with guessed byte
               offsets using mean frame size)

          18 clip
               amount of clipped samples, non-zero only if decoder reports that
               (generic does, some optimized ones not)

          p+0.014
               pitch change (increased/decreased playback sampling rate on user
               request)

     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, have mpg123 decode to a file and then use an
          appropriate utility to play that file with less CPU load.  Most
          probably you can configure mpg123 to produce a format suitable for
          your audio device (see above about encodings and sampling rates).

          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

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                                     29 Feb 2016

          Mostly MPEG-1 layer 2 and 3 are tested in real life.  Please report
          any issues and provide test files to help fixing them.

          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.

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

          Original 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

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