diff -urN midi_prog-/Makefile midi_prog/Makefile
--- midi_prog-/Makefile	Mon Apr 20 00:00:00 2015
+++ midi_prog/Makefile	Tue Apr 21 00:00:00 2015
@@ -6,7 +6,7 @@
 OBJS += cui_tone.o
 CFLAGS += -Wall -I..
 
-VCD_OBJS = vcd.o in.o filter.o out.o util.o
+VCD_OBJS = vcd.o in.o filter.o out.o wrt.o util.o
 
 all: $(TARG) vcd
 
diff -urN midi_prog-/vcd.c midi_prog/vcd.c
--- midi_prog-/vcd.c	Mon Apr 20 00:00:00 2015
+++ midi_prog/vcd.c	Tue Apr 21 00:00:00 2015
@@ -3,14 +3,28 @@
 #include "filter.h"
 #include "out.h"
 #include "ch.h"
+#include "wrt.h"
 
 struct vcd_rec{
 	struct filter_rec fl;
 	struct filter_stat_rec stat;
 	struct out_rec *ot;
-	FILE *ofp;
+
+	int ch, tempo, div4;
+	int smp_cnt, tm, cnt;
+	double abs_sum;
+	int last_v;
 } vcd_inf[ MIDI_CH_N ];
 
+int last_tm = 0;
+
+void
+out_delta(int tm)
+{
+	wrt_delta(tm - last_tm);
+	last_tm = tm;
+}
+
 double
 vcd_freq(int ch)
 {
@@ -21,32 +35,54 @@
 }
 
 void
-vcd_init(struct vcd_rec *vcd, int ch, double fl_Q, struct out_rec *ot, char *name)
+vcd_init(struct vcd_rec *vcd, int ch, double fl_Q, struct out_rec *ot, int tempo, int div4)
 {
-	char fname[1024];
-
 	vcd->fl.type = BPF;
 	vcd->fl.freq = vcd_freq(ch);
 	vcd->fl.Q = fl_Q;	
 	filter_init(&vcd->fl, &vcd->stat, ot->smp_t);
 
 	vcd->ot = ot;
-	sprintf(fname, "%s-%d", name, ch);
-	vcd->ofp = fopen(fname, "w");
+	vcd->ch = ch;
+	vcd->tempo = tempo;
+	vcd->div4 = div4;
+	vcd->smp_cnt = vcd->tm = vcd->cnt = 0;
+	vcd->abs_sum = 0;
+	vcd->last_v = 0;
 }
 
-void
-vcd_fini(struct vcd_rec *vcd)
+int
+is_update_vcd_tm(struct vcd_rec *vcd)
 {
-	fclose(vcd->ofp);
+	int bak = vcd->tm;
+	vcd->tm = (int)(1000000.0 * vcd->smp_cnt * vcd->div4 * vcd->ot->smp_t  / vcd->tempo);
+	return vcd->tm != bak;
 }
 
 void
 vcd_out(struct vcd_rec *vcd, double v)
 {
+	int vol;
+
 	v = filter_out(&vcd->stat, v);
-	vcd->ot->fp = vcd->ofp;
-	out_do(vcd->ot, v);
+
+	vcd->smp_cnt++;
+	vcd->cnt++;
+	vcd->abs_sum += v < 0 ? -v : v;
+
+	if(!is_update_vcd_tm(vcd)) return;
+
+	v = vcd->abs_sum / vcd->cnt;
+	vcd->abs_sum = 0;
+	vcd->cnt = 0;
+	if(v > 1) v = 1;
+
+	vol = (int)(127 * v);
+	if(vol == vcd->last_v) return;
+
+	out_delta(vcd->tm);
+	wrt_vol(vcd->ch, vol);
+	vcd->last_v = vol;
 }
 
 int
@@ -54,18 +90,34 @@
 {
 	struct out_rec otr;
 	in_rec_t irec;	
-	char *name = opt_str("-name", ac, av, "test");
 	double v, fl_Q = opt_double("-Q", ac, av, 1.0);
+	int tempo = opt_int("-tempo", ac, av, 500000);
+	int div4 = opt_int("-div4", ac, av, 96);
+	int note = opt_int("-note", ac, av, 69);
 	int i;
 
 	out_init(&otr, ac, av);
 	irec = otr;
 	irec.fp = stdin;
 
-	for(i=0; i<MIDI_CH_N; i++) vcd_init(&vcd_inf[i], i, fl_Q, &otr, name);
+	wrt_header(div4);
+
+	for(i=0; i<MIDI_CH_N; i++){
+		out_delta(0);
+		wrt_vol(i, 0);
+
+		out_delta(0);
+		wrt_prog(i, i);
+
+		out_delta(0);
+		wrt_note_onoff(i, note, 1, 127);
+	}
+
+	for(i=0; i<MIDI_CH_N; i++) vcd_init(&vcd_inf[i], i, fl_Q, &otr, tempo, div4);
 	while(in_do(&irec, &v) != EOF){
 		for(i=0; i<MIDI_CH_N; i++) vcd_out(&vcd_inf[i], v);
 	}
-	for(i=0; i<MIDI_CH_N; i++) vcd_fini(&vcd_inf[i]);
+
+
 	return 0;
 }
diff -urN midi_prog-/wrt.c midi_prog/wrt.c
--- midi_prog-/wrt.c	Thu Jan  1 09:00:00 1970
+++ midi_prog/wrt.c	Tue Apr 21 00:00:00 2015
@@ -0,0 +1,108 @@
+#include "wrt.h"
+
+void
+set_char(char c)
+{
+	putchar(c);
+}
+
+void
+set_str(char *s)
+{
+	while(*s) set_char(*s++);
+}
+
+void
+set_int(int n, int v)
+{
+	while(n--) set_char((v >> n*8) & 0xff);
+}
+
+void
+set_char2_wrt(char c1, char c2)
+{
+	set_char(c1);
+	set_char(c2);
+}
+
+void
+set_char3_wrt(char c1, char c2, char c3)
+{
+	set_char(c1);
+	set_char(c2);
+	set_char(c3);
+}
+
+void
+wrt_header(int div4)
+{
+	set_str("MThd");
+	set_int(4, 6);
+	set_int(2, 0);
+	set_int(2, 1);
+	set_int(2, div4);
+	set_str("MTrk");
+	set_int(4, 0);
+}
+
+void
+wrt_note_onoff(int ch, int note, int onoff, int velo)
+{
+	int hi = onoff ? 9 : 8;
+	int low = ch;
+	set_char3_wrt((hi<<4) | low, note, velo);
+}
+
+void
+wrt_prog(int ch, int prog)
+{
+	int hi = 0xc;
+	int low = ch;
+	set_char2_wrt((hi<<4) | low, prog);
+}
+
+void
+wrt_ctl_chg(int ch, int type, int v)
+{
+	int hi = 0xb;
+	int low = ch;
+	set_char3_wrt((hi<<4) | low, type, v);
+}
+
+void
+wrt_vol(int ch, int vol)
+{
+	wrt_ctl_chg(ch, 7, vol);
+}
+
+void
+wrt_set_tempo(int ch, int tempo)
+{
+	int hi = 0xf;
+	int low = ch;
+	set_char2_wrt((hi<<4) | low, 3);
+	set_int(3, tempo);
+}
+
+void
+wrt_delta(int v)
+{
+	char buf[8], *bp;
+
+	if(v < 0 || v > 100){
+		fprintf(stderr, "v=%d", v);
+		exit(1);
+	}
+
+	if(v == 0){
+		putchar(0);
+		return;
+	}
+	bp = buf;
+	while(v){
+		*bp++ = v & 0x7f;
+		v >>= 7;
+	}
+	while(--bp != buf) putchar(0x80 | *bp);
+	putchar(*bp);
+}
diff -urN midi_prog-/wrt.h midi_prog/wrt.h
--- midi_prog-/wrt.h	Thu Jan  1 09:00:00 1970
+++ midi_prog/wrt.h	Tue Apr 21 00:00:00 2015
@@ -0,0 +1,18 @@
+#ifndef __WRT_H__
+
+#include "util.h"
+
+void set_char(char c);
+void set_str(char *s);
+void set_int(int n, int v);
+void set_char2_wrt(char c1, char c2);
+void set_char3_wrt(char c1, char c2, char c3);
+void wrt_header(int div4);
+void wrt_note_onoff(int ch, int note, int onoff, int velo);
+void wrt_prog(int ch, int prog);
+void wrt_ctl_chg(int ch, int type, int v);
+void wrt_vol(int ch, int vol);
+void wrt_set_tempo(int ch, int tempo);
+void wrt_delta(int v);
+
+#endif