240 lines
3.7 KiB
Text
240 lines
3.7 KiB
Text
.TH AUDIO 1
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.SH NAME
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mp3dec, mp3enc, oggdec, oggenc, flacdec \- decode and encode audio files
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.SH SYNOPSIS
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.B audio/mp3dec
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[
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.B -d
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]
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.br
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.B audio/oggdec
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.br
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.B audio/flacdec
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.PP
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.B audio/oggenc
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.br
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.B audio/mp3enc
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[
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.B -hprv
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] [
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.B -b
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.I bitrate
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] [
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.B -B
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.I bitrate
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] [
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.B -m
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.I mode
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] [
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.B -q
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q ] [
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.B -s
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.I sfreq
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] [
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.B -V
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.I q
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] [
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.I "long or silly options"
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]
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.PP
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.SH DESCRIPTION
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These programs decode and encode various audio formats from and to
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16-bit stereo PCM (little endian). The decoders read the compressed
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audio data from standard input and produce PCM on standard output at
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a sampling frequency of 44.1KHz.
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.PP
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.I Mp3dec
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decodes MPEG audio (layer 1, 2 and 3). The
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.B -d
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option enables debug output to standard error.
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.I Oggdec
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and
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.I flacdec
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are like
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.I mp3dec
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but decode OGG Vorbis and FLAC lossless audio.
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.PP
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The encoders read PCM on standard input and produce compressed audio
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on standard output.
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.I Oggenc
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and
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.I mp3enc
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produce OGG Vorbis and MP3 audio. For
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.I mp3enc,
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the MP3 file will use `constant bit-rate' (CBR) encoding by default,
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but that can be changed via
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.B --abr
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(average bitrate desired, ABR)
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or
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.BR -v
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(variable bitrate, VBR).
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.SS Options
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.TF "\fB-b \fP"
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.TP
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.B -b
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set minimum allowed
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.I bitrate
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in Kb/s for VBR, default 32Kb/s.
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For CBR,
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set the exact bitrate in Kb/s, which defaults to 128Kb/s.
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.TP
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.B -B
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set maximum allowed
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.I bitrate
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in Kb/s for VBR, default 256Kb/s.
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.TP
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.BI -h
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same as
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.LR "-q 2" .
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.TP
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.B -m
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.I mode
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may be
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(s)tereo,
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(j)oint,
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(f)orce
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or
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(m)ono
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(default j).
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.B force
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forces mid/side stereo on all frames.
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.TP
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.B -p
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add CRC error protection (adds an additional 16 bits per frame to the stream).
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This seems to break playback.
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.TP
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.B -q
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sets output quality to
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.I q
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(see
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.BR -V ).
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.TP
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.B -r
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input is raw pcm
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.TP
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.B -s
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set sampling frequency of input file (in KHz) to
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.IR sfreq ,
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default is 44.1.
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.TP
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.B -v
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use variable bitrate (VBR) encoding
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.TP
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.B -V
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set quality setting for VBR to
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.IR q .
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Default
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.I q
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is 4;
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0 produces highest-quality and largest files, and
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9 produces lowest-quality and smallest files.
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.SS Long options
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.TF "\fB--resample sfreq \fP"
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.TP
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.BI --abr " bitrate"
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sets average
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.I bitrate
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desired in Kb/s, instead of setting quality,
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and generates ABR encoding.
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.TP
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.BI --resample " sfreq"
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set sampling frequency of output file (in KHz) to
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.IR sfreq ,
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default is input sfreq.
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.TP
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.BI --mp3input
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.I input
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is an MP3 file
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.
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.SS Silly options
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.TF --nohist
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.TP
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.BI -f
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same as
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.LR "-q 7" .
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Such a deal.
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.TP
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.BI -o
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mark as non-original (i.e. do not set the original bit)
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.TP
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.BI -c
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mark as copyright
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.TP
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.BI -k
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disable sfb=21 cutoff
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.TP
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.BI -e " emp"
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de-emphasis n/5/c
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(default n)
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.TP
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.BI -d
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allow channels to have different blocktypes
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.TP
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.BI -t
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disable Xing VBR informational tag
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.TP
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.BI -a
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autoconvert from stereo to mono file for mono encoding
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.TP
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.BI -x
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force byte-swapping of input (see
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.IR dd (1)
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instead)
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.TP
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.BI -S
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don't print progress report, VBR histograms
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.TP
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.BI --athonly
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only use the ATH for masking
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.TP
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.BI --nohist
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disable VBR histogram display
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.TP
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.BI --voice
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experimental voice mode
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.
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.SH EXAMPLE
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Plays back a
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.L .mp3
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.IP
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.EX
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audio/mp3dec <foo.mp3 >/dev/audio
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.EE
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.LP
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Encode a
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.L .wav
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file as highest-quality MP3.
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.IP
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.EX
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audio/mp3enc -q 0 -b 320
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.EE
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.LP
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Create a fixed 128Kb/s MP3 file from a
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.L .wav
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file.
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.IP
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.EX
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audio/mp3enc -h <foo.wav >foo.mp3
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.EE
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.LP
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Streaming from stereo 44.1KHz raw PCM data, encoding mono at 16KHz
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(you may not need
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.IR dd ):
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.IP
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.EX
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dd -conv swab | audio/mp3enc -a -r -m m --resample 16 -b 24
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.EE
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.SH SOURCE
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.B /sys/src/cmd/audio
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.SH "SEE ALSO"
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.IR play (1),
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.IR juke (7),
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.IR playlistfs (7)
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.br
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.B http://www.underbit.com/products/mad/
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.br
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.B http://xiph.org/doc/
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.br
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.B http://flac.sourceforge.net/documentation.html
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.SH BUGS
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It's another GNU behemoth, lightly tamed.
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