diff -urN midi_prog-/Makefile midi_prog/Makefile
--- midi_prog-/Makefile	2015-04-19 00:00:00.000000000 +0900
+++ midi_prog/Makefile	2015-04-20 00:00:00.000000000 +0900
@@ -6,15 +6,18 @@
 OBJS += cui_tone.o
 CFLAGS += -Wall -I..
 
-all: $(TARG)
+VCD_OBJS = vcd.o in.o filter.o out.o util.o
+
+all: $(TARG) vcd
 
 $(TARG): $(OBJS)
 	$(CC) -o $@ $(OBJS) $(LIB)
 
-#txprm: txprm.c util.o
-#	$(CC) -o $@ txprm.c util.o -lm
+vcd: $(VCD_OBJS)
+	$(CC) -o $@ $(VCD_OBJS) -lm
 
 clean:
 	rm -f $(TARG) $(OBJS) *~
+	rm -f vcd $(VCD_OBJS)
 
 # EOF
diff -urN midi_prog-/in.c midi_prog/in.c
--- midi_prog-/in.c	1970-01-01 09:00:00.000000000 +0900
+++ midi_prog/in.c	2015-04-20 00:00:00.000000000 +0900
@@ -0,0 +1,13 @@
+#include "in.h"
+
+int
+in_do(in_rec_t *inp, double *vp)
+{
+	int c = EOF;
+
+	if((c = fgetc(inp->fp)) == EOF) return c;
+	if(inp->bit_len == 16) c |= fgetc(inp->fp) << 8;
+	if(c > inp->iv_max) c -= inp->iv_max * 2;
+	*vp = (double)(c - inp->base) / inp->amp;
+	return 0;
+}
diff -urN midi_prog-/in.h midi_prog/in.h
--- midi_prog-/in.h	1970-01-01 09:00:00.000000000 +0900
+++ midi_prog/in.h	2015-04-20 00:00:00.000000000 +0900
@@ -0,0 +1,10 @@
+#ifndef __IN_H__
+#define __IN_H__
+
+#include "out.h"
+
+typedef struct out_rec in_rec_t;
+
+int in_do(in_rec_t *inp, double *vp);
+
+#endif
diff -urN midi_prog-/util.c midi_prog/util.c
--- midi_prog-/util.c	2015-04-17 00:00:00.000000000 +0900
+++ midi_prog/util.c	2015-04-20 00:00:00.000000000 +0900
@@ -28,6 +28,15 @@
 	return strtol(s, NULL, 0);
 }
 
+double
+opt_double(char *key, int ac, char **av, double def)
+{
+	char *s;
+
+	if((s = opt_str(key, ac, av, NULL)) == NULL) return def;
+	return strtod(s, NULL);
+}
+
 struct stklst *
 stklst_alloc(int size, struct stklst *prev)
 {
diff -urN midi_prog-/util.h midi_prog/util.h
--- midi_prog-/util.h	2015-04-17 00:00:00.000000000 +0900
+++ midi_prog/util.h	2015-04-20 00:00:00.000000000 +0900
@@ -17,6 +17,7 @@
 int opt_idx(char *key, int ac, char **av);
 char *opt_str(char *key, int ac, char **av, char *def);
 int opt_int(char *key, int ac, char **av, int def);
+double opt_double(char *key, int ac, char **av, double def);
 
 
 struct stklst{
diff -urN midi_prog-/vcd.c midi_prog/vcd.c
--- midi_prog-/vcd.c	1970-01-01 09:00:00.000000000 +0900
+++ midi_prog/vcd.c	2015-04-20 00:00:00.000000000 +0900
@@ -0,0 +1,71 @@
+#include "util.h"
+#include "in.h"
+#include "filter.h"
+#include "out.h"
+#include "ch.h"
+
+struct vcd_rec{
+	struct filter_rec fl;
+	struct filter_stat_rec stat;
+	struct out_rec *ot;
+	FILE *ofp;
+} vcd_inf[ MIDI_CH_N ];
+
+double
+vcd_freq(int ch)
+{
+	int H = MIDI_CH_N / 2;
+	return ch < H ?
+		500 + (1000.0 - 500) * ch / (H-1) :
+		1500 + (3000.0 - 1500) * (ch-H) / (H-1);
+}
+
+void
+vcd_init(struct vcd_rec *vcd, int ch, double fl_Q, struct out_rec *ot, char *name)
+{
+	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");
+}
+
+void
+vcd_fini(struct vcd_rec *vcd)
+{
+	fclose(vcd->ofp);
+}
+
+void
+vcd_out(struct vcd_rec *vcd, double v)
+{
+	v = filter_out(&vcd->stat, v);
+	vcd->ot->fp = vcd->ofp;
+	out_do(vcd->ot, v);
+}
+
+int
+main(int ac, char **av)
+{
+	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 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);
+	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;
+}