mp2enc(1)
NAME
mp2enc - Simple MPEG-1 layer-II audio encoder
SYNOPSIS
mp2enc [-v num] [-b bitrate_kbps] [-r output_sampling_rate_hz] [-R rate,chans,bits] [-s ] [-m ] [-e ] [-V ] [-?] -o output_filename
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
mjpegtools(1) primarily for reasons of completeness and because it is
able to perform sampling rate conversion.
Those seeking a faster (and probably higher quality) layer II encoder
are recommended to use toolame(1) which can be obtained from:
http://www.planckenergy.com
GENERAL FUNCTION LETTERS
-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)).
-v num Set verbosity level to num. 0 = warnings and errors only, 1 =
information as well, 2=really verbose. -? Display a synopsis
of the command syntax.
-R rate,chans,bits
Indicate, that the input is raw PCM without header. You must
specify 3 numbers: rate is the samplerate in Hz, chans is the
number of channels (1 or 2) and bits is the number of bits per
sample. 8 bits are unsigned, 16 bits are signed in machine
native byte order.
FUNCTION LETTERS CONTROLLING OUTPUT STREAM STRUCTURE
-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.
-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.
-l layer
Sets the audio layer. Legal values are 1 and 2. The default is
layer II.
-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.
-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.
-e Use CRC error protection.
-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
-V 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.
-o outputpathname
The name of the output file to generate. If '-' is given as the
pathname output is written to standard output.
BUGS
Mono output does not work for layer I.
AUTHOR
This man page was written by Andrew Stevens.
If you have questions, remarks, problems or you just want to contact
the developers, the main mailing list for the MJPEG-tools is:
mjpeg-users@lists.sourceforge.net
For more info, see our website at
http://mjpeg.sourceforge.net
SEE ALSO
mpeg2enc(1), mp2enc(1), lavrec(1), lavplay(1), lav2yuv(1), lav2wav(1), yuvscaler(1)
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