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-
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- mmmmppppgggg111122223333((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((22221111 AAAApppprrrr 1111999999997777)))) mmmmppppgggg111122223333((((1111))))
-
-
-
- NNNNAAAAMMMMEEEE
- mpg123 - play audio MPEG 1.0/2.0 file (layers 1, 2 and 3)
-
- SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
- mmmmppppgggg111122223333 [ ----ttttssssccccvvvvqqqqyyyy00001111mmmm22224444 ] [ ----bbbb _s_i_z_e ] [ ----kkkk _n_u_m ] [ ----nnnn _n_u_m ] [
- ----ffff _f_a_c_t_o_r ] [ ----rrrr _r_a_t_e ] [ ----gggg _g_a_i_n ] [ ----aaaa _d_e_v ] [ ----oooo ssss | ----oooo hhhh
- | ----oooo llll ] [ ----dddd _n ] [ ----hhhh _n ] [ ----pppp _p_r_o_x_y ] [ ----@@@@ _f_i_l_e ] _f_i_l_e ...
- | _U_R_L ... | ----
-
- DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
- mmmmppppgggg111122223333 reads one or more _f_i_l_es (or standard input if ``-''
- is specified) or _U_R_Ls and plays them on the audio device
- (default) or outputs them to stdout. _f_i_l_e/_U_R_L is assumed to
- be an MPEG-1/2 audio bit stream.
-
- OOOOPPPPTTTTIIIIOOOONNNNSSSS
- mmmmppppgggg111122223333 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 ``--''.
-
- ----tttt, --------tttteeeesssstttt
- Test mode. The audio stream is decoded, but no output
- occurs.
-
- ----ssss, --------ssssttttddddoooouuuutttt
- 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 mmmmppppgggg111122223333. The output format
- is raw (headerless) linear PCM audio data, 16 bit,
- stereo, host byte order.
-
- ----cccc, --------cccchhhheeeecccckkkk
- Check for filter range violations, and report them for
- each frame if any occur.
-
- ----vvvv, --------vvvveeeerrrrbbbboooosssseeee
- Increase the verbosity level. For example, displays
- the frame numbers during decoding.
-
- ----qqqq, --------qqqquuuuiiiieeeetttt
- Quiet. Suppress diagnostic messages.
-
- ----yyyy, --------rrrreeeessssyyyynnnncccc
- 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 mmmmppppgggg111122223333 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.
-
-
-
- Page 1 (printed 3/2/99)
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- mmmmppppgggg111122223333((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((22221111 AAAApppprrrr 1111999999997777)))) mmmmppppgggg111122223333((((1111))))
-
-
-
- ----0000, --------ssssiiiinnnngggglllleeee0000; ----1111,
- Decode only channel 0 (left) or channel 1 (right),
- respectively. These options are available for stereo
- MPEG streams only.
-
- ----mmmm, --------ssssiiiinnnngggglllleeeemmmmiiiixxxx
- Mix both channels. This option is available for stereo
- MPEG layer-3 streams only. It takes less CPU time than
- full stereo decoding.
-
- ----2222, --------2222ttttoooo1111; ----4444,
- 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.
-
- ----bbbb _s_i_z_e, --------bbbbuuuuffffffffeeeerrrr _s_i_z_e
- Use an audio output buffer of _s_i_z_e 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.
-
- ----kkkk _n_u_m, --------sssskkkkiiiipppp _n_u_m
- Skip first _n_u_m frames. By default the decoding starts
- at the first frame.
-
- ----nnnn _n_u_m, --------ffffrrrraaaammmmeeeessss _n_u_m
- Decode only _n_u_m frames. By default the complete stream
- is decoded.
-
- ----ffff _f_a_c_t_o_r, --------ssssccccaaaalllleeee _f_a_c_t_o_r
- Change scale factor (default: 32768).
-
- ----rrrr _r_a_t_e, --------rrrraaaatttteeee _r_a_t_e
- Set sample rate (default: automatic). You don't want
- to change this.
-
- ----gggg _g_a_i_n, --------ggggaaaaiiiinnnn _g_a_i_n
- Set audio hardware output gain (default: don't change).
-
- ----aaaa _d_e_v, --------aaaauuuuddddiiiiooooddddeeeevvvviiiicccceeee _d_e_v
- 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.
-
- ----oooo ssss, --------ssssppppeeeeaaaakkkkeeeerrrr
- Direct audio output to the speaker.
-
-
-
-
- Page 2 (printed 3/2/99)
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- mmmmppppgggg111122223333((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((22221111 AAAApppprrrr 1111999999997777)))) mmmmppppgggg111122223333((((1111))))
-
-
-
- ----oooo hhhh, --------hhhheeeeaaaaddddpppphhhhoooonnnneeeessss
- Direct audio output to the headphone connector.
-
- ----oooo llll, --------lllliiiinnnneeeeoooouuuutttt
- Direct audio output to the line-out connector.
-
- ----dddd _n, --------ddddoooouuuubbbblllleeeessssppppeeeeeeeedddd _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
- --------hhhhaaaallllffffssssppppeeeeeeeedddd option to play 3 out of 4 frames etc.
- Don't expect great sound quality when using this
- option.
-
- ----hhhh _n, --------hhhhaaaallllffffssssppppeeeeeeeedddd _n
- Play each frame _n times. This will cause the MPEG
- stream to be played at 1/n'_t_h speed (n times slower),
- which can be used for special effects. Can also be
- combined with the --------ddddoooouuuubbbblllleeeessssppppeeeeeeeedddd option to double every
- third frame or things like that. Don't expect great
- sound quality when using this option.
-
- ----pppp _U_R_L | nnnnoooonnnneeee, --------pppprrrrooooxxxxyyyy _U_R_L | nnnnoooonnnneeee
- The specified _p_r_o_x_y 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 nnnnoooonnnneeee
- means not to use any proxy, and to retrieve files
- directly from the respective servers. See also the
- ``HTTP SUPPORT'' section.
-
- ----@@@@ _f_i_l_e, --------lllliiiisssstttt _f_i_l_e
- Read filenames and/or URLs of MPEG audio streams from
- the specified _f_i_l_e in addition to the ones specified on
- the command line (if any). Note that _f_i_l_e 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).
-
- OOOOPPPPEEEERRRRAAAANNNNDDDDSSSS
- The following operands are supported:
-
- _f_i_l_e(s) The path name(s) of one or more input files. They
- must be valid MPEG-1/2 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
- _U_R_L (see next section).
-
-
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- Page 3 (printed 3/2/99)
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- mmmmppppgggg111122223333((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((22221111 AAAApppprrrr 1111999999997777)))) mmmmppppgggg111122223333((((1111))))
-
-
-
- HHHHTTTTTTTTPPPP SSSSUUUUPPPPPPPPOOOORRRRTTTT
- In addition to reading MPEG audio streams from ordinary
- files and from the standard input, mmmmppppgggg111122223333 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, mmmmppppgggg111122223333 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, mmmmppppgggg111122223333 examines the
- environment for variables named MMMMPPPP3333____HHHHTTTTTTTTPPPP____PPPPRRRROOOOXXXXYYYY, hhhhttttttttpppp____pppprrrrooooxxxxyyyy
- and HHHHTTTTTTTTPPPP____PPPPRRRROOOOXXXXYYYY, 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 ----pppp command line option (see
- the ``OPTIONS'' section). Specifying ----pppp nnnnoooonnnneeee 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 ----bbbb 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 llllyyyynnnnxxxx(1)) and then play them from there.
-
- IIIINNNNTTTTEEEERRRRRRRRUUUUPPPPTTTT
- You can abort mmmmppppgggg111122223333 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.
-
- SSSSEEEEEEEE AAAALLLLSSSSOOOO
- llllyyyynnnnxxxx(1), ssssooooxxxx(1), iiiinnnnttttrrrroooo(1)
-
- NNNNOOOOTTTTEEEESSSS
- 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
-
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- Page 4 (printed 3/2/99)
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- mmmmppppgggg111122223333((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((22221111 AAAApppprrrr 1111999999997777)))) mmmmppppgggg111122223333((((1111))))
-
-
-
- processor. You can also use the ----ssssiiiinnnngggglllleeeemmmmiiiixxxx option to decode
- mono only, which reduces the CPU load somewhat for layer-3
- streams. See also the ----2222 and ----4444 options.
-
- If everything else fails, use the ----ssss 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 ssssooooxxxx(1) to convert the output to an audio
- format suitable for your audio player.
-
- Also note that mmmmppppgggg111122223333 always generates 16 bit stereo data
- (if one of the ----ssssiiiinnnngggglllleeee* 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 ssssooooxxxx(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 ----bbbb option to use a
- buffer of at least 1000 Kbytes.
-
- BBBBUUUUGGGGSSSS
- 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 ----ssss
- option has to be used on those platforms.
-
- AAAAUUUUTTTTHHHHOOOORRRRSSSS
- Main author:
- Michael Hipp <Michael.Hipp@student.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.sfs.nphil.uni-tuebingen.de/~hipp/mpg123.html
-
-
-
- Page 5 (printed 3/2/99)
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- mmmmppppgggg111122223333((((1111)))) UUUUNNNNIIIIXXXX SSSSyyyysssstttteeeemmmm VVVV ((((22221111 AAAApppprrrr 1111999999997777)))) mmmmppppgggg111122223333((((1111))))
-
-
-
- http://www.heim3.tu-clausthal.de/~olli/mpg123/
- (includes information about the mpg123 mailing list)
-
- The latest version is also available from here:
- ftp.tu-clausthal.de:/pub/unix/audio/mpg123
- http://ftp.tu-clausthal.de/pub/unix/audio/mpg123
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