diff --git a/src/thread/pipipelinethread.h b/src/thread/pipipelinethread.h
index 10b33291..4d815a14 100644
--- a/src/thread/pipipelinethread.h
+++ b/src/thread/pipipelinethread.h
@@ -114,7 +114,7 @@ public:
 	void setWaitNextPipe(bool wait) {wait_next_pipe = wait;}
 
 protected:
-	virtual Tout calc(const Tin &v, bool &ok) = 0;
+	virtual Tout calc(Tin &v, bool &ok) = 0;
 
 private:
 	void begin() {cnt = 0;}
@@ -122,7 +122,7 @@ private:
 		mutex.lock();
 		if (in.isEmpty()) {
 			mutex.unlock();
-			piMSleep(1);
+			piMSleep(10);
 			return;
 		}
 		if (next_overload && wait_next_pipe) {