[CentOS] Stripping silent periods from MP3s

Sun Dec 12 17:48:36 UTC 2010
Keith Roberts <keith at karsites.net>

I'm on Centos 5.5, and would like to use sox to strip out 
any periods of silence > 5 seconds from a batch mp3 audio 

Googling I found sox, but it does not seem to support mp3 
files by default.

The man page says:

.mp3      MP3 Compressed Audio

MP3 audio files come from the MPEG standards  for  audio and  video 
compression.   They  are a lossy compression format that achieves
good compression rates with a mini- mum  amount  of quality loss. 
Also see Ogg Vorbis for a similar format.

MP3 support  in  SoX  is  optional  and requires  access  to  either
or both the external libmad and libmp3lame libraries.  To see if 
there  is  support for  Mp3  run  sox  -h and look for it under the
list of supported file formats as "mp3".

libmad is installed:

Installed Packages
Name       : libmad
Arch       : i386
Version    : 0.15.1b
Release    : 4.el5.rf
Size       : 138 k
Repo       : installed
Summary    : MPEG audio decoding library
URL        : http://www.underbit.com/products/mad/
License    : GPL
Description: MAD (libmad) 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.
            : MAD does not yet support MPEG-2 multichannel audio (although it
            : should be backward compatible with such streams) nor does it
            : currently support AAC.

SoX is installed:

Name       : sox
Arch       : i386
Version    : 12.18.1
Release    : 1.el5_5.1
Size       : 659 k
Repo       : installed
Summary    : A general purpose sound file conversion tool.
URL        : http://sox.sourceforge.net/
License    : GPL
Description: SoX (Sound eXchange) is a sound file format converter SoX can convert
            : between many different digitized sound formats and perform simple
            : sound manipulation functions, including sound effects.

[root at karsites ~]# sox -h
sox: Version 12.18.1

Usage: [ gopts ] [ fopts ] ifile [ fopts ] ofile [ effect [ effopts ] ]

gopts: -e -h -p -q -S -V

fopts: -r rate -c channels -s/-u/-U/-A/-a/-i/-g/-f -b/-w/-l/-d -v volume -x

effect: avg band bandpass bandreject chorus compand copy dcshift
deemph earwax echo echos fade filter flanger highp highpass lowp
lowpass mask mcompand noiseprof noisered pan phaser pick pitch
polyphase rate repeat resample reverb reverse silence speed stat
stretch swap synth trim vibro vol

effopts: depends on effect

Supported file formats: aiff al alsa au auto avr cdr cvs dat vms gsm
hcom la lu maud nul ossdsp prc raw sb sf sl smp sndt sph 8svx sw txw
ub ul uw voc vorbis vox wav wve

Yet the mp3 support is not showing up for SoX in the above 
list of supported file formats.

Any suggestions how to tell SoX to use the mp3 format I 
need please?

Or are there any other programs that can be used to strip 
silent periods from MP3's?

Using Audacity to manually edit each sound file is 
definately NOT and option.

Kind Regards,

Keith Roberts

In theory, theory and practice are the same;
in practice they are not.

This email was sent from my laptop with Centos 5.5