fix missing version change

lib/recorder.js

@@ -117,9 +117,9 @@ HlsStreamRecorder.prototype.process = function(obj, next) {
   if (segment.key && !segment.key.iv) {
     var seqStr = obj.seq.toString();
     segment.key.iv = '0x00000000000000000000000000000000'.slice(-seqStr.length) + seqStr;
-    if (index.version > 2) {
-      index.version = 2;
-      debug('changed index version to:', index.version);
+    if (this.index.version > 2) {
+      this.index.version = 2;
+      debug('changed index version to:', this.index.version);
     }
   }