only disk cache around the playhead

app/widget/timeruler/timeruler.cpp

@@ -109,9 +109,9 @@ void TimeRuler::SetScroll(int s)
   update();
 }
 
-void TimeRuler::CacheInvalidatedRange(const rational& in, const rational& out)
+void TimeRuler::CacheInvalidatedRange(const TimeRange& range)
 {
-  dirty_cache_ranges_.InsertTimeRange(TimeRange(in, out));
+  dirty_cache_ranges_.InsertTimeRange(range);
 
   update();
 }

app/widget/timeruler/timeruler.h

@@ -48,7 +48,7 @@ public slots:
 
   void SetScroll(int s);
 
-  void CacheInvalidatedRange(const rational& in, const rational& out);
+  void CacheInvalidatedRange(const TimeRange &range);
 
   void CacheTimeReady(const rational& time);