NAME
mp3enc – create mp3 audio files

SYNOPSIS
games/mp3enc [ –hprv ] [ –b bitrate ] [ –B bitrate ] [ –m mode ] [ –q q ] [ –s sfreq ] [ –V q ] [ long or silly options ]

DESCRIPTION
Mp3enc compresses audio on standard input, normally PCM–encoded, and produces MP3–encoded audio on standard output. By default, the MP3 file will use `constant bit–rate' (CBR) encoding, but that can be changed via ––abr (average bitrate desired, ABR) or –v (variable bitrate, VBR).

Options
b   set minimum allowed bitrate in Kb/s for VBR, default 32Kb/s. For CBR, set the exact bitrate in Kb/s, which defaults to 128Kb/s.
B   set maximum allowed bitrate in Kb/s for VBR, default 256Kb/s.
h   same as –q 2.
m   mode may be (s)tereo, (j)oint, (f)orce or (m)ono (default j). force forces mid/side stereo on all frames.
p   add CRC error protection (adds an additional 16 bits per frame to the stream). This seems to break playback.
q   sets output quality to q (see –V).
r   input is raw pcm
s   set sampling frequency of input file (in KHz) to sfreq, default is 44.1.
v   use variable bitrate (VBR) encoding
V   set quality setting for VBR to q. Default q is 4; 0 produces highest–quality and largest files, and 9 produces lowest–quality and smallest files.

Long options
––abr bitrate      sets average bitrate desired in Kb/s, instead of setting quality, and generates ABR encoding.
––resample sfreqset sampling frequency of output file (in KHz) to sfreq, default is input sfreq.
––mp3input      input is an MP3 file

Silly options
f         same as –q 7. Such a deal.
o         mark as non–original (i.e. do not set the original bit)
c         mark as copyright
k         disable sfb=21 cutoff
e emp     de–emphasis n/5/c (default n)
d         allow channels to have different blocktypes
t         disable Xing VBR informational tag
a         autoconvert from stereo to mono file for mono encoding
x         force byte–swapping of input (see dd(1) instead)
S         don't print progress report, VBR histograms
––athonlyonly use the ATH for masking
––nohist   disable VBR histogram display
––voice    experimental voice mode

EXAMPLES
Encode a .wav file as highest–quality MP3.
games/mp3enc –q 0 –b 320

Create a fixed 128Kb/s MP3 file from a .wav file.
games/mp3enc –h <foo.wav >foo.mp3

Streaming from stereo 44.1KHz raw PCM data, encoding mono at 16KHz (you may not need dd):
dd –conv swab | games/mp3enc –a –r –m m ––resample 16 –b 24

SOURCE
/sys/src/games/mp3enc

SEE ALSO
dd(1), mp3dec(1), audio(3), cdfs(4), audio(7), juke(7), playlistfs(7)
http://www.sulaco.org/mp3

BUGS
Quality is much better than encoders based on the ISO routines, but still not as good as the FhG encoder.

It's a GNU behemoth, lightly rehabilitated. There are zillions of undocumented options.

Copyright © 2018 Alcatel-Lucent. All rights reserved.