From 59934436c41da5c999a065638d2e951a34110b03 Mon Sep 17 00:00:00 2001
From: Harvie <tomas@mudrunka.cz>
Date: Wed, 1 Aug 2012 00:47:42 +0200
Subject: [PATCH] Improved Goertzel + DTMF decoder example

---
 c/goertzel/dtmf.sh    |  71 +++++++++++++++++++++++++++
 c/goertzel/goertzel.c | 109 ++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 176 insertions(+), 4 deletions(-)
 create mode 100755 c/goertzel/dtmf.sh

diff --git a/c/goertzel/dtmf.sh b/c/goertzel/dtmf.sh
new file mode 100755
index 0000000..6c7798e
--- /dev/null
+++ b/c/goertzel/dtmf.sh
@@ -0,0 +1,71 @@
+#!/bin/bash
+#This is sample implementation of DTMF decoder using my C implementation of Goertzel Algorithm
+#This is not very efficient or precise, it's just proof of concept
+#Usage example: arecord 2>/dev/null | ./dtmf.sh
+
+tresh=3
+last='';
+./goertzel -i -q -r 8000 -s 400 -t $tresh -f 697 -f 770 -f 852 -f 941 -f 1209 -f 1336 -f 1477 -f 1633 | while read line; do
+	#echo "$line";
+
+	#Get time
+	pos="$(echo "$line" | cut -f 1)";
+
+	#Get values for each tone
+	a="$(echo "$line" | cut -f 2)";
+	b="$(echo "$line" | cut -f 3)";
+	c="$(echo "$line" | cut -f 4)";
+	d="$(echo "$line" | cut -f 5)";
+	e="$(echo "$line" | cut -f 6)";
+	f="$(echo "$line" | cut -f 7)";
+	g="$(echo "$line" | cut -f 8)";
+	h="$(echo "$line" | cut -f 9)";
+
+	#Compare values to treshold
+	test $a -gt $tresh && a=true || a=false
+	test $b -gt $tresh && b=true || b=false
+	test $c -gt $tresh && c=true || c=false
+	test $d -gt $tresh && d=true || d=false
+	test $e -gt $tresh && e=true || e=false
+	test $f -gt $tresh && f=true || f=false
+	test $g -gt $tresh && g=true || g=false
+	test $h -gt $tresh && h=true || h=false
+
+	#echo "$pos: $a $b $c $d $e $f $g $h";
+	state="$a$b$c$d$e$f$g$h";
+
+	#Test if tones changed since last time
+	#echo test "$state" != "$last"
+	test "$state" != "$last" && {
+
+		#DTMF Table
+		$a && {
+			$e && echo -n '1'
+			$f && echo -n '2'
+			$g && echo -n '3'
+			$h && echo -n 'A'
+		}
+		$b && {
+			$e && echo -n '4'
+			$f && echo -n '5'
+			$g && echo -n '6'
+			$h && echo -n 'B'
+		}
+		$c && {
+			$e && echo -n '7'
+			$f && echo -n '8'
+			$g && echo -n '9'
+			$h && echo -n 'C'
+		}
+		$d && {
+			$e && echo -n '*'
+			$f && echo -n '0'
+			$g && echo    '#'
+			$h && echo -n 'D'
+		}
+
+	}
+
+	last="$state"
+
+done
diff --git a/c/goertzel/goertzel.c b/c/goertzel/goertzel.c
index bcf7a91..f5250a0 100644
--- a/c/goertzel/goertzel.c
+++ b/c/goertzel/goertzel.c
@@ -1,10 +1,15 @@
 #include <stdio.h>
 #include <math.h>
+#include <getopt.h>
+
 
 /*
 	Usage examples
 	arecord | ./goertzel
 	sox input.mp3 -b 8 -c 1 -r 8000 -t wav - | ./goertzel
+
+	Arguments for DTMF decoding:
+	-f 697 -f 770 -f 852 -f 941 -f 1209 -f 1336 -f 1477 -f 1633 -t 10
 */
 
 float goertzel_mag(int numSamples,int TARGET_FREQUENCY,int SAMPLING_RATE, float* data)
@@ -48,7 +53,18 @@ float goertzel_mag(int numSamples,int TARGET_FREQUENCY,int SAMPLING_RATE, float*
     return magnitude;
 }
 
-int main() {
+void print_help(char ** argv) {
+	printf("help me %s\n", argv[0]);
+}
+
+void addfreq(int *freqs, int freq) {
+	int i = 0;
+	while(freqs[i]!=-1) i++;
+	freqs[i]=freq;
+	freqs[i+1]=-1;
+}
+
+int main(int argc, char ** argv) {
 	/*
 	int samples[] = {0,1,2,3,4,5,6,7,8,9,8,7,6,5,4,3,2,1};
 	int samplecount = 18;
@@ -58,19 +74,104 @@ int main() {
 
 	int samplerate = 8000;
 	int samplecount = 4000;
+	int treshold = -1;
+	char noreturn = 0;
+	char integers=0;
+	char verbose=1;
+	int freqs[argc+1]; freqs[0]=-1;
+
+	int opt;
+	while ((opt = getopt(argc, argv, "?r:s:f:t:iqn")) != -1) {
+		switch (opt) {
+			case 'r':
+				samplerate = atoi(optarg);
+				break;
+			case 's':
+				samplecount = atoi(optarg);
+				break;
+			case 'f':
+				addfreq(freqs, atoi(optarg));
+				break;
+			case 't':
+				treshold = atoi(optarg);
+				break;
+			case 'i':
+				integers = 1;
+				break;
+			case 'n':
+				noreturn = 1;
+				break;
+			case 'q':
+				verbose = 0;
+				break;
+			case '?':
+				print_help(argv);
+				return 0;
+				break;
+		}
+	}
+
+	if(freqs[0]==-1) addfreq(freqs, 440);
 	float samples[samplecount];
 	float position = 0;
-	fprintf(stderr,"Position (Secs)\tMagnitude\n");
+
+	if(verbose) {
+		fprintf(stderr,
+			"#Detected tone: %d Hz\n"
+			"#Samplerate: %d Hz\n"
+			"#Frame lenght: %d samples\n"
+			"#Treshold: %d\n"
+			"#\n"
+			,freqs[0],samplerate,samplecount,treshold);
+		fflush(stderr);
+
+		printf("#Position");
+		int i; for(i=0;freqs[i]!=-1;i++) {
+			printf("\t%2dHz",freqs[i]);
+		}
+		puts("");
+	}
+
+	char print=0, printnow=0, printlast = 0;
 	while(!feof(stdin)) {
 		int i;
+
+		//Sample data
 		for(i=0;i<samplecount && !feof(stdin);i++) {
 			unsigned char sample;
 			fread(&sample,1,1,stdin);
 			samples[i]=sample;
 			//printf("%d\n", sample);
 		}
+
+		//Apply goertzel
+		float power[argc];
+		print=0;
+		for(i=0;freqs[i]!=-1;i++) {
+			power[i] = goertzel_mag(samplecount, freqs[i], samplerate, samples);
+
+			//Set print true if over treshold or if changed to false (print for the last time after going under treshold)
+			printnow = power[i] > treshold;
+			print = print || printnow || (printlast && !noreturn);
+		}
+		printlast = printnow;
+		fflush(stdout);
+
+		//Print data
+		if(print) {
+			printf("%8.2f", position);
+			for(i=0;freqs[i]!=-1;i++) {
+				printf("\t");
+				if(integers)
+					printf("%d",(int)power[i]);
+				else
+					printf("%.4f",power[i]);
+			}
+			puts("");
+			fflush(stdout);
+		}
+
+		//Increase time
 		position += ((float)samplecount/(float)samplerate);
-		float power = goertzel_mag(samplecount, 440, samplerate, samples);
-		printf("%f\t%f\n", position, power);
 	}
 }
-- 
2.30.2