Acoustic event detector

software/apps/audio_module/event_detector/Makefile

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+# makefile for user application
+
+# the current directory
+APP_DIR := $(dir $(abspath $(lastword $(MAKEFILE_LIST))))
+
+# files needed for this code
+C_SRCS   := $(wildcard *.c) 
+INCLUDE_PATHS += . ./kiss_fft ./kiss_fft/tools ./log2fix/
+
+CFLAGS += -DFIXED_POINT=16 -std=c99
+CFLAGS += -Wno-type-limits -Wno-sign-compare
+
+TOCK_BOARD = audio_module
+
+# include makefile settings that are shared between applications
+include ../../AppMakefile.mk
+

software/apps/audio_module/event_detector/README.md

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+# Fixed-point ridge tracker for acoustic event detection in C
+
+## Quick start
+```
+make clean
+make
+./main input.wav
+```
+Use test.ipynb to visualize the resulting \*.mat files
+
+## Prerequisites
+* Fixed-point FFT: git clone https://github.com/longle2718/kiss_fft
+* Fixed-point log: git clone https://github.com/dmoulding/log2fix
+* libsndfile: sudo apt-get install libsndfile1-dev 

software/apps/audio_module/event_detector/common.h

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+#ifndef __COMMON_H__
+#define __COMMON_H__
+
+#include "_kiss_fft_guts.h"
+
+#define BUF_LEN     (512)
+#define INC_LEN     (BUF_LEN/2)
+#define FRE_LEN     (BUF_LEN/2)
+
+#define S_SQ(a)     S_MUL((a),(a)) // scalar square
+#define S_DIV(a,b)  S_MUL((a),SAMP_MAX/(b)) // a < b
+#define MAX(a,b)    (((a) > (b)) ? (a) : (b))
+#define MIN(a,b)    (((a) < (b)) ? (a) : (b))
+#define ABS(a)      (((a) < 0) ? -(a): (a))
+// Magnitude Estimator 
+// http://dspguru.com/book/export/html/62
+#define ALPHA       ((kiss_fft_scalar)(0.947543636291*SAMP_MAX))
+#define BETA        ((kiss_fft_scalar)(0.392485425092*SAMP_MAX))
+#define MAG(r,i)    ( S_MUL(ALPHA,MAX(ABS((r)),ABS((i)))) + S_MUL(BETA,MIN(ABS((r)),ABS((i)))) )
+
+#endif

software/apps/audio_module/event_detector/dynArray.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include "dynArray.h"
+#include "_kiss_fft_guts.h"
+
+void initArray(Array *a, size_t initialSize) {
+    a->maxSize = initialSize;
+    a->used = 0;
+
+    a->size = a->maxSize;
+    printf("Init array size = %zu\n",a->size);
+    a->SNR = malloc(a->size * sizeof(kiss_fft_scalar));
+    a->FI = malloc(a->size * sizeof(size_t));
+    a->TI = malloc(a->size * sizeof(size_t));
+}
+
+void insertArray(Array *a, kiss_fft_scalar snr, size_t fi, size_t ti) {
+    // a->used is the number of used entries, because a->array[a->used++] updates a->used only *after* the array has been accessed.
+    // Therefore a->used can go up to a->size 
+    if (a->size > 0 && a->used == a->size) {
+        a->maxSize *= 2;
+        printf("Doubled array max size to %zu\n",a->maxSize);
+    }
+    if (a->size < a->maxSize) {
+        a->size = a->maxSize;
+        // with NULL ptr, realloc == malloc
+        a->SNR = realloc(a->SNR, a->size * sizeof(kiss_fft_scalar));
+        a->FI = realloc(a->FI, a->size * sizeof(size_t));
+        a->TI = realloc(a->TI, a->size * sizeof(size_t));
+    }
+    a->SNR[a->used] = snr;
+    a->FI[a->used] = fi;
+    a->TI[a->used] = ti;
+    a->used++;
+}
+
+void freeArray(Array *a) {
+    free(a->SNR);
+    free(a->FI);
+    free(a->TI);
+    a->SNR = NULL;
+    a->FI = NULL;
+    a->TI = NULL;
+    a->used = a->size = 0;
+}
+size_t getMaxDurArray(Array a){
+    if (a.used == 0)
+        return 0;
+
+    size_t minTI = a.TI[0];
+    size_t maxTI = a.TI[a.used-1];
+    return maxTI-minTI;
+}
+
+kiss_fft_scalar getAvgSNRArray(Array a){
+    if (a.used == 0)
+        return 0;
+
+    SAMPPROD sum = 0;
+    for (size_t k=0; k < a.used; k++){
+        sum += a.SNR[k];
+    }
+    return (kiss_fft_scalar)(sum/a.used);
+}

software/apps/audio_module/event_detector/dynArray.h

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+#ifndef __DYNARRAY_H__
+#define __DYNARRAY_H__
+
+#include "kiss_fft.h"
+
+typedef struct {
+    kiss_fft_scalar *SNR; // log SNR
+    size_t *FI; // frequency index
+    size_t *TI; // time index
+    size_t size;
+    size_t used;
+    size_t maxSize;
+} Array;
+
+void initArray(Array *a, size_t initialSize);
+void insertArray(Array *a, kiss_fft_scalar snr, size_t fi, size_t ti);
+void freeArray(Array *a);
+
+size_t getMaxDurArray(Array a);
+kiss_fft_scalar getAvgSNRArray(Array a);
+#endif