mp2enc.1

Motion JPEG编解码器源代码

.TH "mp2enc" "1" "2 June 2001" "MJPEG Linux Square" "MJPEG tools manual"

.SH "NAME"
.LP 
.br 
mp2enc \- Simple MPEG-1 layer-II audio encoder
.br 

.SH "SYNOPSIS"
.B mp2enc
.RB [ -v
.IR num ]
.RB [ -b
.IR bitrate_kbps ]
.RB [ -r
.IR output_sampling_rate_hz ]
.RB [ -s
]
.RB [ -m
]
.RB [ -e
]
.RB [ -V
]
.RB [ -? ]
.BI -o \ output_filename

.SH "DESCRIPTION"
Mp2enc is a simple MPEG-1 layer-I/II audio encoder.  It is actually a very
mildly warmed over version of the MPEG Software Simulation Group's
reference encoder.  It accepts a WAV file or stream on stdin and
ouputs an a layer-I/II elementary audio stream.  It is included in the
\fBmjpegtools\fP(1) primarily for reasons of completeness and because it
is able to perform sampling rate conversion.
.PP
Those seeking a faster (and probably higher quality) layer II encoder are
recommended to use \fBtoolame\fP(1) which can be obtained from:
.IP
\fIhttp://www.planckenergy.com\fP


.SH "GENERAL FUNCTION LETTERS"
.TP
.BI -o \ output_filename
Specifies the name for the output file.

An integer format code (e.g. %d) in the name is replaced the number of
the file generated (see printf(3)).
.TP
.BI -v \ num
Set verbosity level to num.  0 = warnings and errors only, 1 = information as well, 2=really verbose.
.B -?
Display a synopsis of the command syntax.
.br
.SH "FUNCTION LETTERS CONTROLLING OUTPUT STREAM STRUCTURE"
.TP
.BI -b \ bitrate

This sets the bit-rate of the output stream in kBit/sec.  Typical
values for layer II might be 224kbps for good-quality audio suitable for capturing
Dolby pro-logic signals.  A rate of 192kbps or 128kbps is reasonable
for low quality audio (e.g. mono TV audio).  Really high compression
is, of course, better achieved using MPEG-1 layer III ("MP3") audio
encoding or AAC. A more appropriate value for layer I might be 384kbps.

.TP
.BI -r \ sampling_rate
Sets the audio sampling rate of the reconstructed output signal in Hz.
Legal values are 32000, 44100 and 48000Hz.   mp2enc will automatically
sample-rate convert the input signal if necessary.

.TP
.BI -l \ layer
Sets the audio layer.
Legal values are 1 and 2. The default is layer II.

.TP
.BI -s
Force stereo output.  A mono input signal is channel doubled before
encoding to make it stereo.  This is useful for players
which simply can't handle a non-stero signal.
.TP
.BI -m
Force mono output.  A stereo input signal is down-mixed before encoding.
Useful if you've captured a mono signal in stereo and your player can
handle mono MPEG-1 Layer 2 audio.
.TP
.BI -e
Use CRC error protection.
.TP
.BI -V
Force VCD compatible output. The primary effect of this is to make certain that
the sampling rate is set to 44100 (-r 44100).  The VCD2.0 specifications 
permit mono audio at 64, 
96 and 192 kbits/sec and stereo at 128, 192, 224, and 384 kbits/sec. Using 
\fB-V\fP checks that the bitrate is valid for the number of channels.
The defaults (unless -m or -b are used) are stereo at 224 kbits/sec.
.TP
.BI -o \ outputpathname
The name of the output file to generate.  If '-' is given as the pathname output is written to standard output.
.SH "BUGS"
Mono output does not work for layer I.
.SH AUTHOR
This man page was written by Andrew Stevens.
.br
If you have questions, remarks, problems or you just want to contact
the developers, the main mailing list for the MJPEG\-tools is:
  \fImjpeg\[e-mail]\fP

.TP
For more info, see our website at
.I http://mjpeg.sourceforge.net

.SH "SEE ALSO"
.BR mpeg2enc "(1), " mp2enc "(1), " lavrec "(1), " lavplay "(1), "
.BR lav2yuv "(1), " lav2wav "(1), " yuvscaler "(1)"