handle sidechain input changes

[ardour.git] / libs / ardour / dsp_filter.cc

diff --git a/libs/ardour/dsp_filter.cc b/libs/ardour/dsp_filter.cc
index 3026666b79efc7e9d77bc2a8a47f55df3cae2331..2678d0008c4671b64493acddea23e293b04fa4c5 100644 (file)
--- a/libs/ardour/dsp_filter.cc
+++ b/libs/ardour/dsp_filter.cc
@@ -19,6 +19,7 @@
 
 #include <stdlib.h>
 #include <math.h>
+#include "ardour/dB.h"
 #include "ardour/dsp_filter.h"
 
 #ifndef M_PI
@@ -41,6 +42,28 @@ ARDOUR::DSP::mmult (float *data, float *mult, const uint32_t n_samples) {
        }
 }
 
+float
+ARDOUR::DSP::log_meter (float power) {
+       // compare to gtk2_ardour/logmeter.h
+       static const float lower_db = -192.f;
+       static const float upper_db = 0.f;
+       static const float non_linearity = 8.0;
+       return (power < lower_db ? 0.0 : powf ((power - lower_db) / (upper_db - lower_db), non_linearity));
+}
+
+float
+ARDOUR::DSP::log_meter_coeff (float coeff) {
+       if (coeff <= 0) return 0;
+       return log_meter (fast_coefficient_to_dB (coeff));
+}
+
+void
+ARDOUR::DSP::peaks (float *data, float &min, float &max, uint32_t n_samples) {
+       for (uint32_t i = 0; i < n_samples; ++i) {
+               if (data[i] < min) min = data[i];
+               if (data[i] > max) max = data[i];
+       }
+}
 
 LowPass::LowPass (double samplerate, float freq)
        : _rate (samplerate)