feat: iterate on SsfStepDetector

* use SSF signal instead of accelerometer signal
* use higher BEAT_CORR_THR_{12} for SSF signal
* add absolute SSF_THRESHOLD to ignore small accelero bumps
* compute ssf_threshold according to detected SSF peaks, not the mean (more robust vs. noise)

pasada-lib/include/iir_filter.h

@@ -13,7 +13,7 @@
 class Buf {
 protected:
     std::vector<double> data;
-    size_t size;
+    size_t N;
     size_t n;
 public:
     Buf(size_t N);
@@ -21,7 +21,7 @@ public:
 };
 
 /** Running filter base. */
-class Filt : Buf {
+class Filt : public Buf {
 protected:
     std::vector<double> taps;
     size_t shift;
@@ -31,6 +31,9 @@ public:
     double filter(double val);
     double peek();
     void push(double val);
+    /** prime the filter by overwriting the entire buffer with 'val' */
+    void prime(double val);
+    size_t size();
 };
 
 /** Running IIR filter. */

pasada-lib/include/pd_signal.h

@@ -6,6 +6,7 @@
 #define PASADASUPERPROJECT_SIGNAL_H
 
 #include <vector>
+#include <deque>
 
 namespace pd_signal {
     /** `num` evenly spaced numbers over interval [start,stop] */
@@ -33,6 +34,8 @@ namespace pd_signal {
 
     /** two-dimensional mean of a collection of signals */
     void mean(std::vector<double> &out, std::vector<std::vector<double> >& m);
+    /** two-dimensional mean of a collection of signals */
+    void mean(std::vector<double> &out, std::deque<std::vector<double> >& m);
 
 }
 

pasada-lib/include/ssf_filter.h

@@ -37,10 +37,12 @@ protected:
     const size_t LEN_TH_WIN;
     size_t num_samples;
     double ssf_threshold;
+    double ssf_threshold_nm1;
+    Filt f_ssf_threshold_smoothing;
     size_t len_refr;
     size_t n_refr;
     bool is_refr;
-    double nm1_ssf;
+    double ssf_nm1;
     Filt f_ssf_mean;
 public:
     /**