diff -urN midi_prog-/vcd.c midi_prog/vcd.c
--- midi_prog-/vcd.c	2015-04-21 01:00:00.000000000 +0900
+++ midi_prog/vcd.c	2015-04-22 00:00:00.000000000 +0900
@@ -7,7 +7,7 @@
 
 struct vcd_rec{
 	struct filter_rec fl;
-	struct filter_stat_rec stat;
+	struct filter_stat_rec stat, stat_lpf;
 	struct out_rec *ot;
 
 	int ch, tempo, div4;
@@ -35,12 +35,14 @@
 }
 
 void
-vcd_init(struct vcd_rec *vcd, int ch, double fl_Q, struct out_rec *ot, int tempo, int div4)
+vcd_init(struct vcd_rec *vcd, int ch, double fl_Q, double lpf_freq, double lpf_Q, struct out_rec *ot, int tempo, int div4)
 {
+	struct filter_rec lpf = { LPF, lpf_freq, lpf_Q };
 	vcd->fl.type = BPF;
 	vcd->fl.freq = vcd_freq(ch);
 	vcd->fl.Q = fl_Q;	
 	filter_init(&vcd->fl, &vcd->stat, ot->smp_t);
+	filter_init(&lpf, &vcd->stat_lpf, ot->smp_t);
 
 	vcd->ot = ot;
 	vcd->ch = ch;
@@ -68,7 +70,7 @@
 
 	vcd->smp_cnt++;
 	vcd->cnt++;
-	vcd->abs_sum += v < 0 ? -v : v;
+	vcd->abs_sum += filter_out(&vcd->stat_lpf, v < 0 ? -v : v);
 
 	if(!is_update_vcd_tm(vcd)) return;
 
@@ -90,7 +92,9 @@
 {
 	struct out_rec otr;
 	in_rec_t irec;	
-	double v, fl_Q = opt_double("-Q", ac, av, 1.0);
+	double v, fl_Q = opt_double("-Q", ac, av, 20);
+	double lpf_freq = opt_double("-lpf_freq", ac, av, 20);
+	double lpf_Q = opt_double("-lpf_Q", ac, av, 0.8);
 	int tempo = opt_int("-tempo", ac, av, 500000);
 	int div4 = opt_int("-div4", ac, av, 96);
 	int note = 69;
@@ -123,7 +127,7 @@
 		}
 	}
 
-	for(i=0; i<MIDI_CH_N; i++) vcd_init(&vcd_inf[i], i, fl_Q, &otr, tempo, div4);
+	for(i=0; i<MIDI_CH_N; i++) vcd_init(&vcd_inf[i], i, fl_Q, lpf_freq, lpf_Q, &otr, tempo, div4);
 	while(in_do(&irec, &v) != EOF){
 		for(i=0; i<MIDI_CH_N; i++) vcd_out(&vcd_inf[i], v);
 	}