Update position event for https://github.com/TooTallNate/node-lame

decoder.js

if (ret == MPG123_NEW_FORMAT) {

  var format = binding.mpg123_getformat(mh);
  debug('new format!', format);
  self.emit('format', format);

  var positionTimeIntervalID = setInterval(function() {
    
    var current = binding.mpg123_tellframe(mh);
    var total = binding.mpg123_length(mh);

    self.emit('update', current, total);

  }, 0);

  return read();
}

node_mpg123.cc

Handle<Value> node_mpg123_length (const Arguments& args) {
  UNWRAP_MH;
  return scope.Close(Number::New(mpg123_length(mh)));
}

NODE_SET_METHOD(target, "mpg123_length", node_mpg123_length);