gistfile1.txt

    function _screenShotInternal(callback) {
      // get correct dimensions
      self._prepare(function(err, meta) {
        if (meta.durationsec) {
          // check if all timemarks are inside duration
          if (timemarks !== null) {
            for (var i = 0; i < timemarks.length; i++) {
              if (parseInt(timemarks[i]) > (meta.durationsec * 0.9)) {
                // remove timemark from array
                timemarks.splice(i, 1);
              }
            }
            // if there are no more timemarks around, add one at end of the file
            if (timemarks.length == 0) {
              timemarks[0] = (meta.durationsec * 0.9);
            }
          }
          // get positions for screenshots (using duration of file minus 10% to remove fade-in/fade-out)
          var secondOffset = (meta.durationsec * 0.9) / screenshotcount;
          var donecount = 0;
          var series = [];

          var i = 1;

          // use async helper function to generate all screenshots and
          // fire callback just once after work is done
          async.until(
            function() {
              return i > screenshotcount;
            },
            function(taskcallback) {
              var offset;
              if (timemarks !== null) {
                // get timemark for current iteration
                offset = timemarks[(i - 1)];
              } else {
                offset = secondOffset * i;
              }
              var target = Meta.escapedPath(folder + '/tn_' + offset + 's.jpg');
              var input = Meta.escapedPath(self.options.inputfile); //<============ changed from this.options.inputfile