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 files. 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