reducer should be a pure function

react/features/local-recording/actionTypes.js

  * (as in: {@code RecordingAdapter} is actively collecting audio data).
  *
  * {
- *     type: LOCAL_RECORDING_ENGAGED
+ *     type: LOCAL_RECORDING_ENGAGED,
+ *     recordingEngagedAt: Date
  * }
  */
 export const LOCAL_RECORDING_ENGAGED = Symbol('LOCAL_RECORDING_ENGAGED');
     = Symbol('LOCAL_RECORDING_TOGGLE_DIALOG');
 
 /**
- * Action to update {@code LocalRecordingInfoDialog} with stats
- * from all clients.
+ * Action to update {@code LocalRecordingInfoDialog} with stats from all
+ * clients.
  *
  * {
- *     type: LOCAL_RECORDING_STATS_UPDATE
+ *     type: LOCAL_RECORDING_STATS_UPDATE,
+ *     stats: Object
  * }
  */
 export const LOCAL_RECORDING_STATS_UPDATE

react/features/local-recording/actions.js

 // recording in the UI.
 
 /**
- * Signals that local recording has started.
+ * Signals that local recording has been engaged.
  *
+ * @param {Date} startTime - Time when the recording is engaged.
  * @returns {{
- *     type: LOCAL_RECORDING_ENGAGED
+ *     type: LOCAL_RECORDING_ENGAGED,
+ *     recordingEngagedAt: Date
  * }}
  */
-export function localRecordingEngaged() {
+export function localRecordingEngaged(startTime: Date) {
     return {
-        type: LOCAL_RECORDING_ENGAGED
+        type: LOCAL_RECORDING_ENGAGED,
+        recordingEngagedAt: startTime
     };
 }
 

react/features/local-recording/components/LocalRecordingInfoDialog.js

      * The start time of the current local recording session.
      * Used to calculate the duration of recording.
      */
-    recordingStartedAt: Date,
+    recordingEngagedAt: Date,
 
     /**
      * Stats of all the participant.
         this._timer = setInterval(
             () => {
                 this.setState((_prevState, props) => {
-                    const nowTime = new Date(Date.now());
+                    const nowTime = new Date();
 
                     return {
                         durationString: this._getDuration(nowTime,
-                            props.recordingStartedAt)
+                            props.recordingEngagedAt)
                     };
                 });
                 try {
  *     encodingFormat: string,
  *     isModerator: boolean,
  *     isOn: boolean,
- *     recordingStartedAt: Date,
+ *     recordingEngagedAt: Date,
  *     stats: Object
  * }}
  */
     const {
         encodingFormat,
         isEngaged: isOn,
-        recordingStartedAt,
+        recordingEngagedAt,
         stats
     } = state['features/local-recording'];
     const isModerator
         encodingFormat,
         isModerator,
         isOn,
-        recordingStartedAt,
+        recordingEngagedAt,
         stats
     };
 }

react/features/local-recording/middleware.js

         // react to state changes in recordingController.
         recordingController.onStateChanged = function(isEngaged) {
             if (isEngaged) {
-                dispatch(localRecordingEngaged());
+                const nowTime = new Date();
+
+                dispatch(localRecordingEngaged(nowTime));
             } else {
                 dispatch(localRecordingUnengaged());
             }

react/features/local-recording/reducer.js

         return {
             ...state,
             isEngaged: true,
-            recordingStartedAt: new Date(Date.now()),
+            recordingEngagedAt: action.recordingEngagedAt,
             encodingFormat: recordingController._format
         };
     }
         return {
             ...state,
             isEngaged: false,
-            recordingStartedAt: null
+            recordingEngagedAt: null
         };
     case LOCAL_RECORDING_TOGGLE_DIALOG:
         return {