diff -urN midi_prog-/pitdet.c midi_prog/pitdet.c
--- midi_prog-/pitdet.c	Fri Sep 25 00:00:00 2015
+++ midi_prog/pitdet.c	Sat Sep 26 00:00:00 2015
@@ -111,7 +111,8 @@
 	}
 
 	for(j=0; j<pd->m; j++){
-		tbuf_set_dbl(&pd->arr[j].ab.tb, sec, pd->wk[j].v);
+		double v = MAX(pd->wk[j].v, 0);
+		tbuf_set_dbl(&pd->arr[j].ab.tb, sec, v);
 	}
 }
 
@@ -234,6 +235,8 @@
 	int from_i, to_i, i;
 	struct onoff_stat *ost = &p->ost;
 
+	chatt_set(&ost->ct, 0);
+	chatt_set(&ost->ct2, 0);
 	ost->v = 0;
 	ost->on_sec = -1;
 	ost->off_sec = 0;
diff -urN midi_prog-/tool.c midi_prog/tool.c
--- midi_prog-/tool.c	Fri Sep 25 00:00:00 2015
+++ midi_prog/tool.c	Sat Sep 26 00:00:00 2015
@@ -135,30 +135,6 @@
 	return velo;
 }
 
-int
-note_onoff_is_overtone(struct note_onoff *nto, double on_sec, double off_sec)
-{
-	/* Fundamental, Overtone */
-
-	int lst[] = { 12, 12+7, 12*2 };
-	int lst_n = ARR_N(lst);
-	int i, t;
-	double v = note_onoff_v(nto, on_sec, off_sec);
-
-	for(i=0; i<lst_n; i++){
-		struct note_onoff *funda;
-		int n = i + 2;
-		double v_f;
-
-		if((t = nto->note - lst[i]) < 0) continue;
-		funda = &note_onoff[t]; /* ! */
-		v_f = note_onoff_v(funda, on_sec, off_sec);
-
-		if(v_f >= v * n * 0.7) return 1;
-	}
-	return 0;
-}
-
 void
 note_onoff_add(struct note_onoff *nto, double sec, double v, int ch)
 {