X-Git-Url: https://git.sesse.net/?p=pitch;a=blobdiff_plain;f=pitch.cpp;h=97238f5f05b1a99113837029199f44434b1f220e;hp=658066b0edcf1911f08f253ad5a462c10e8fd873;hb=f4906bf100acb8c5875196b7c2306effdd6a091d;hpb=9fb7e2081d99ba0e13dee47a1d37fbbfd769f8d0

diff --git a/pitch.cpp b/pitch.cpp
index 658066b..97238f5 100644
--- a/pitch.cpp
+++ b/pitch.cpp
@@ -27,7 +27,9 @@ void read_chunk(int fd, double *in, unsigned num_samples);
 void apply_window(double *in, double *out, unsigned num_samples);
 std::pair<double, double> find_peak(double *in, unsigned num_samples);
 void find_peak_magnitudes(std::complex<double> *in, double *out, unsigned num_samples);
+std::pair<double, double> adjust_for_overtones(std::pair<double, double> base, double *in, unsigned num_samples);
 double bin_to_freq(double bin, unsigned num_samples);
+double freq_to_bin(double freq, unsigned num_samples);
 std::string freq_to_tonename(double freq);
 std::pair<double, double> interpolate_peak(double ym1, double y0, double y1);
 void print_spectrogram(double freq, double amp);
@@ -58,6 +60,7 @@ int main()
 		fftw_execute(p);
 		find_peak_magnitudes(out, bins, FFT_LENGTH);
 		std::pair<double, double> peak = find_peak(bins, FFT_LENGTH);
+		peak = adjust_for_overtones(peak, bins, FFT_LENGTH);
 
 		if (peak.first < 50.0 || peak.second - log10(FFT_LENGTH) < 0.0) {
 #if TUNING == WELL_TEMPERED_GUITAR
@@ -90,6 +93,11 @@ int get_dsp_fd()
 	int rate = SAMPLE_RATE;
 	ioctl(fd, SOUND_PCM_WRITE_RATE, &rate);
 
+	int max_fragments = 2;
+	int frag_shift = ffs(FFT_LENGTH / OVERLAP) - 1;
+	int fragments = (max_fragments << 16) | frag_shift;
+        ioctl(fd, SNDCTL_DSP_SETFRAGMENT, &fragments);
+	
 	ioctl(3, SNDCTL_DSP_SYNC, 0);
 	
 	return fd;
@@ -226,6 +234,9 @@ std::pair<double, double> find_peak(double *in, unsigned num_samples)
 		}
 	}
 
+	if (best_bin == 0 || best_bin == num_samples / 2) {
+		return std::make_pair(-1.0, 0.0);
+	}
 	std::pair<double, double> peak = 
 		interpolate_peak(in[best_bin - 1],
 				 in[best_bin],
@@ -234,10 +245,65 @@ std::pair<double, double> find_peak(double *in, unsigned num_samples)
 	return std::make_pair(bin_to_freq(double(best_bin) + peak.first, num_samples), peak.second);
 }
 
+// it's perhaps not ideal to _first_ find the peak and _then_ the harmonics --
+// ideally, one should find the set of all peaks and then determine the likely
+// base from that... something for later. :-)
+std::pair<double, double> adjust_for_overtones(std::pair<double, double> base, double *in, unsigned num_samples)
+{
+	double mu = base.first, var = 1.0 / (base.second * base.second);
+		
+	//printf("Base at %.2f (amp=%5.2fdB)\n", base.first, base.second);
+
+	for (unsigned i = 2; i < 10; ++i) {
+		unsigned middle = unsigned(floor(freq_to_bin(base.first, num_samples) * i + 0.5));
+		unsigned lower = middle - (i+1)/2, upper = middle + (i+1)/2;
+
+		if (upper >= num_samples)
+			upper = num_samples - 2;
+
+		// printf("Searching in [%u,%u] = %f..%f\n", lower, upper, bin_to_freq(lower, num_samples), bin_to_freq(upper, num_samples));
+
+		// search for a peak in this interval
+		double best_harmonics_freq = -1.0;
+		double best_harmonics_amp = -1.0;
+		for (unsigned j = lower; j <= upper; ++j) {
+			if (in[j] > in[j-1] && in[j] > in[j+1]) {
+				std::pair<double, double> peak =
+					interpolate_peak(in[j - 1],
+						in[j],
+						in[j + 1]);
+				
+				if (peak.second > best_harmonics_amp) {
+					best_harmonics_freq = bin_to_freq(j + peak.first, num_samples);
+					best_harmonics_amp = peak.second;
+				}
+			}
+		}
+
+		if (best_harmonics_amp <= 0.0)
+			continue;
+
+		//printf("Found overtone %u at %.2f (amp=%5.2fdB)\n", i, best_harmonics_freq,
+		//	 best_harmonics_amp);
+
+		double this_mu = best_harmonics_freq / double(i);
+		double this_var = 1.0 / (best_harmonics_amp * best_harmonics_amp);
+
+		double k = var / (var + this_var);
+		mu = (1.0 - k) * mu + k * this_mu;
+		var *= (1.0 - k);
+	}
+	return std::make_pair(mu, base.second);
+}
+
 double bin_to_freq(double bin, unsigned num_samples)
 {
 	return bin * SAMPLE_RATE / double(num_samples);
 }
+double freq_to_bin(double freq, unsigned num_samples)
+{
+	return freq * double(num_samples) / double(SAMPLE_RATE);
+}
 
 /*
  * Given three bins, find the interpolated real peak based