madplay.1

一个嵌入式Linux上的mp3播放器

.\"
.\" madplay - MPEG audio decoder and player
.\" Copyright (C) 2000-2004 Robert Leslie
.\"
.\" This program is free software; you can redistribute it and/or modify
.\" it under the terms of the GNU General Public License as published by
.\" the Free Software Foundation; either version 2 of the License, or
.\" (at your option) any later version.
.\"
.\" This program is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public License
.\" along with this program; if not, write to the Free Software
.\" Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
.\"
.\" $Id: madplay.1,v 1.51 2004/02/23 21:34:53 rob Exp $
.\"
.TH MADPLAY 1 "22 February 2004" "MAD" "MPEG Audio Decoder"
.SH NAME
madplay \- decode and play MPEG audio stream(s)
.SH SYNOPSIS
.B madplay
.RI [ options ]
.I file
\&...
.br
.B madplay
.RI [ options ]
\fB\-o\fR [\fItype\fB:\fR]\fIpath\fR
.I file
\&...
.SH DESCRIPTION
.B madplay
is a command-line MPEG audio decoder and player based on the MAD library
.RI ( libmad ).
.PP
MAD is a high-quality MPEG audio decoder. It currently supports MPEG-1 and the
MPEG-2 extension to Lower Sampling Frequencies, as well as the so-called
MPEG\ 2.5 format. All three audio layers (Layer\ I, Layer\ II, and Layer\ III
a.k.a. MP3) are fully implemented.
.PP
Among the special features of MAD are 24-bit PCM resolution and 100%
fixed-point (integer) computation. Since MAD is implemented entirely without
the use of floating point arithmetic, it performs especially well on
architectures without an FPU.
.PP
MAD does not yet support MPEG-2 multichannel audio (although it should be
backward compatible with such streams) nor does it currently support AAC.
.PP
By default
.B madplay
reads and decodes one or more input
.IR file s
containing MPEG audio data and plays them on the native audio device. If the
input file is a single dash (\-), data is read from standard input.
.PP
Decoded output may optionally be redirected to a file instead of being played
on the audio device by using the
.B \-o
.RB ( \-\-output )
option.
.PP
For each
.IR file ,
.B madplay
will also attempt to read and display ID3 tag information. The supported tag
versions are ID3v1, ID3v1.1, ID3v2.2, ID3v2.3, and ID3v2.4. If a tag contains
relative volume adjustment information (RVA2),
.B madplay
will use the information to adjust the master volume for output. This behavior
can be changed with the
.B \-A
.RB ( \-\-adjust\-volume )
and
.B \-G
.RB ( \-\-replay\-gain )
options.
.PP
If the
.B \-T
.RB ( \-\-show\-tags\-only )
option is used, decoding is not performed but tag information is still
displayed. When used in conjunction with
.B \-v
.RB ( \-\-verbose ),
encoder as well as ID3 tags are shown.
.SH OPTIONS
.SS Verbosity
.TP
.BR \-v " or " \-\-verbose
Generally show more information than the default. During decoding, show
information about the stream including playing time, audio layer, bit rate,
sampling frequency, and stereo mode.
.TP
.BR \-q " or " \-\-quiet
Generally show less information than the default. Do not show any information
during decoding except warnings.
.TP
.BR \-Q " or " \-\-very\-quiet
Generally show no information except severe errors. Do not show any
information or warnings during decoding.
.TP
.BI \-\-display\-time= mode
Set the default verbose time display mode to
.IR mode ,
which must be one of
.BR remaining ,
.BR current ,
or
.BR overall .
This is only relevant with
.B -v
.RB ( \-\-verbose ).
See
.B \-\-tty\-control
below for details on changing the time display mode during playback.
.SS Decoding
.TP
.B \-\-downsample
Reduce the decoded sampling frequency 2:1. This also reduces the computational
overhead of the decoder.
.TP
.BR \-i " or " \-\-ignore\-crc
Ignore CRC information in the audio stream. This causes frames with CRC errors
to be decoded and played anyway. This option is not recommended, but since
some encoders have been known to generate bad CRC information, this option is
a work-around to play streams from such encoders.
.TP
\fB\-\-ancillary\-output=\fIpath\fR
Write ancillary data from the MPEG audio stream to
.IR path .
If
.I path
is a single dash (\-), the data will be written to standard output.
Bits from the ancillary data stream are packed into octets; if any bits
remain, the final octet will be padded with zero bits. See the
.B NOTES
section below for further information about this option.
.SS Audio Output
.TP
\fB\-o\fR or \fB\-\-output=\fR[\fItype\fB:\fR]\fIpath\fR
Direct output to
.IR path ,
rather than playing audio on the native audio device. The format of the output
is specified by
.I type
which can be any of the supported output formats (see
.B Output Formats
below.) If a format is not specified, one will be inferred from
.IR path .
If
.I path
is a single dash (\-), the output will be written to standard output.
.TP
\fB\-b\fR or \fB\-\-bit\-depth=\fIdepth\fR
Request an output precision of
.I depth
bits per sample. Higher bit depths yield higher quality sound. Typical bit
depths are 8, 16, 24, and 32, however other depths may also be possible.
Whether the request can be honored depends on the capabilities of the audio
device or output format.
See the
.B NOTES
section below for further details about this option.
.TP
\fB\-R\fR or \fB\-\-sample\-rate=\fIhertz\fR
Request an output sampling frequency of
.I hertz
samples per second (Hz).
The sample rate must be in the range 1000 to 65535\ Hz.
Whether the request can be honored depends on the capabilities of the audio
device or output format.
If the effective rate is not the same as the rate of the decoded audio, output
may be resampled, possibly resulting in lower quality sound.
.TP
.BR \-d " or " \-\-no\-dither
Do not dither output PCM samples. This may result in lower quality sound but
is useful for analyzing output from the decoder.
.TP
\fB\-\-fade\-in\fR[\fB=\fIduration\fR]
Gradually fade-in the audio from each file over
.IR duration .
If not specified, the default duration is
.B 0:05
(five seconds.)
.TP
\fB\-a\fR or \fB\-\-attenuate=\fIdecibels\fR or \fB\-\-amplify=\fIdecibels\fR
Attenuate or amplify the signal by
.I decibels
(dB).
The signal is attenuated if the decibel value is negative; it is amplified if
the value is positive.
The value must be in the range \-175 to +18\ dB.
The value may be fractional, e.g. \-1.5\ dB.
A value of 0\ dB will leave the signal unchanged.
Each step of 6\ dB will approximately halve (in the negative direction) or
double (in the positive direction) the strength of the signal.
.TP
\fB\-A\fR or \fB\-\-adjust\-volume=\fIdecibels\fR
Adjust the relative volume for all files. This option overrides any per-file
volume adjustment settings. For example,
.B \-A0
may be used to ignore relative volume adjustments given by ID3 tags. Relative
volume adjustments specified by this option or by ID3 tags are used as the
base volume against which the signal is further attenuated or amplified using
the
.B \-a
.RB ( \-\-attenuate ,
.BR \-\-amplify )
option or keyboard controls.
This option cannot be used together with
.B \-G
.RB ( \-\-replay\-gain ).
.TP
\fB\-G\fR or \fB\-\-replay\-gain\fR[\fB=\fIprofile\fR]
Enable Replay Gain volume adjustments. Replay Gain information contained in
the decoded files (if any) is used to make volume adjustments for output. The
.I profile
may be one of
.B radio
(the default) or
.BR audiophile .
See the
.B NOTES
section below for further details. When Replay Gain is enabled, a default
pre-amp gain of +6\ dB is also applied; this can be changed with the
.B \-a
.RB ( \-\-attenuate ,
.BR \-\-amplify )
option.
.SS Channel Selection
.PP
For dual channel streams, an output channel should be selected. If one is not
selected, the first (left) channel will be used.
.PP
For stereo streams, making a channel selection other than stereo will cause
the output to become monaural.
.TP
.BR \-1 " or " \-\-left
Output the first (left) channel only.
.TP
.BR \-2 " or " \-\-right
Output the second (right) channel only.
.TP
.BR \-m " or " \-\-mono
Mix the left and right channels together.
.TP
.BR \-S " or " \-\-stereo
Force stereo output, even if the stream is single or dual channel.
.SS Playback
.TP
\fB\-s\fR or \fB\-\-start=\fItime\fR
Begin playing at
.IR time ,
given as an offset from the beginning of the first file
.RB ( 0:00:00 ),
seeking as necessary.
.TP
\fB\-t\fR or \fB\-\-time=\fIduration\fR
Stop playback after the playing time of the output audio equals
.IR duration .
.TP
.BR \-z " or " \-\-shuffle
Randomize the list of files given on the command line for playback.
.TP
\fB\-r\fR or \fB\-\-repeat\fR[\fB=\fImax\fR]
Play the input files
.I max
times, or indefinitely. Playback can be stopped prematurely by giving a time
limit with the
.B \-t
.RB ( \-\-time )
option. If
.B \-z
.RB ( \-\-shuffle )
is also used, the files will be continuously shuffled and repeated in such a
way that the same file is not played again until at least half of the other
files have played in the interim.
.TP
.B \-\-tty\-control
Enable keyboard controls during playback. This is the default unless standard
input is not a terminal, output is redirected with
.B \-o
.RB ( \-\-output ),
or either of
.B \-q
.RB ( \-\-quiet )
or
.B \-Q
.RB ( \-\-very\-quiet )
is given.
The keyboard controls are:
.RS
.TP 3