AudioAnalyzer.cpp

00001 #include "mbed.h"
00002 #include "AudioAnalyzer.h"
00003 
00004 namespace NK
00005 {
00006 
00007 void AudioAnalyzer::analyze()
00008 {
00009     if (analyzed) return;
00010 
00011     // compute the sum of the squares of the input samples
00012     power = 0;
00013     zeroCrossings = 0;
00014     minValue = 127;
00015     maxValue = -128;
00016     int8_t const * const lastSample = samples + nsamples - 1;
00017     bool sign, lastSign = samples[0] < 0;
00018     for (int8_t const *p = samples; p <= lastSample; p++) {
00019         int8_t val = *p++;
00020         power += ((int16_t)val * val);
00021         sign = (val < 0);
00022         if (sign != lastSign)
00023             zeroCrossings++;
00024         lastSign = sign;
00025         if (val > maxValue)
00026             maxValue = val;
00027         if (val < minValue)
00028             minValue = val;
00029     }
00030     // normalize power
00031     power /= nsamples;
00032     analyzed = true;
00033 }
00034 
00035 }