wav2mp3.js

//usage: $ node wav2mp3.js file1.wav file2.wav
// converts to .mp3 format and deletes original .wav file

var fs = require('fs');
var sys = require('sys');
var Step = require('step');
var spawn = require('child_process').spawn;
var exec = require('child_process').exec;

function convert(file, callback){
  
  if (file.slice(-4) === ".mp3") {
    callback(new Error('file ' + file + ' already converted '));
    return;
  }
  
  Step(
    function checkFile() {
      fs.stat(file, this);
    },
    function convertFile(err) {
      if (err) { callback(err); return; }
      var conversion = exec('soundconverter -b -m ' + 
          'audio/mpeg -s .mp3 ' + file, this);
    },
    function deleteOriginal(err) {
      if (err) { callback(err); return; }
      exec('rm -f ' + file, this);
    },
    callback
  );
};

Step(
  function () {
    var group = this.group();
    process.argv.splice(2).forEach(function (file) {
      convert(file, group());
    });
  },
  function (err, results) {
    if (err) throw err;
    sys.puts(results.length + " successfully converted.");
  }
)