[SCM] calf/master: + MultiChorus: add frequency response graph

[js at users.alioth.debian.org]

The following commit has been merged in the master branch:
commit fc8c597920600116bed3a5b0871cb4351cfdab23
Author: Krzysztof Foltman <wdev at foltman.com>
Date:   Fri Nov 7 20:14:59 2008 +0000

    + MultiChorus: add frequency response graph

diff --git a/src/calf/modules.h b/src/calf/modules.h
index 4769e1c..18be830 100644
--- a/src/calf/modules.h
+++ b/src/calf/modules.h
@@ -713,7 +713,7 @@ public:
 };
 
 /// A multitap stereo chorus thing - processing
-class multichorus_audio_module: public audio_module<multichorus_metadata>
+class multichorus_audio_module: public audio_module<multichorus_metadata>, public line_graph_iface
 {
 public:
     float *ins[in_count]; 
@@ -769,6 +769,16 @@ public:
             *params[par_lfophase_r] = (double)right.lfo.phase * 360.0 / 4096.0;
         return outputs_mask; // XXXKF allow some delay after input going blank
     }
+    bool get_graph(int index, int subindex, float *data, int points, cairo_t *context)
+    {
+        if (index == par_delay && subindex < 2) 
+            return calf_plugins::get_graph(*this, subindex, data, points);
+        return false;
+    }
+    float freq_gain(int subindex, float freq, float srate)
+    {
+        return (subindex ? right : left).freq_gain(freq, srate);                
+    }
 };
 
 extern std::string get_builtin_modules_rdf();
diff --git a/src/calf/multichorus.h b/src/calf/multichorus.h
index 49ee54e..fcd96da 100644
--- a/src/calf/multichorus.h
+++ b/src/calf/multichorus.h
@@ -152,6 +152,31 @@ public:
             lfo.step();
         }
     }
+    float freq_gain(float freq, float sr)
+    {
+        typedef std::complex<double> cfloat;
+        freq *= 2.0 * M_PI / sr;
+        cfloat z = 1.0 / exp(cfloat(0.0, freq)); // z^-1        
+        cfloat h = 0.0;
+        int mds = min_delay_samples + mod_depth_samples * 1024 + 2*65536;
+        int mdepth = mod_depth_samples;
+        mdepth = mdepth >> 2;
+        T scale = lfo.get_scale();
+        unsigned int nvoices = lfo.get_voices();
+        for (unsigned int v = 0; v < nvoices; v++)
+        {
+            int lfo_output = lfo.get_value(v);
+            // 3 = log2(32 >> 2) + 1 because the LFO value is in range of [-65535, 65535] (17 bits)
+            int v = mds + (mdepth * lfo_output >> (3 + 1));
+            int fldp = v >> 16;
+            cfloat zn = std::pow(z, fldp); // z^-N
+            h += zn + (zn * z - zn) * cfloat(v / 65536.0 - fldp);
+        }
+        // simulate a lerped comb filter - H(z) = 1 / (1 + fb * (lerp(z^-N, z^-(N+1), fracpos))), N = int(pos), fracpos = pos - int(pos)
+        // mix with dry signal
+        float v = std::abs(cfloat(gs_dry.get_last()) + cfloat(scale * gs_wet.get_last()) * h);
+        return v;
+    }
 };
 
 };
diff --git a/src/modules.cpp b/src/modules.cpp
index 7d84f50..acf1374 100644
--- a/src/modules.cpp
+++ b/src/modules.cpp
@@ -155,7 +155,7 @@ CALF_PLUGIN_INFO(rotary_speaker) = { 0x8483, "RotarySpeaker", "Calf Rotary Speak
 CALF_PORT_NAMES(multichorus) = {"In L", "In R", "Out L", "Out R"};
 
 CALF_PORT_PROPS(multichorus) = {
-    { 5,        0.1,  10,   0, PF_FLOAT | PF_SCALE_LOG | PF_CTL_KNOB | PF_UNIT_MSEC, NULL, "min_delay", "Minimum delay" },
+    { 5,        0.1,  10,   0, PF_FLOAT | PF_SCALE_LOG | PF_CTL_KNOB | PF_UNIT_MSEC | PF_PROP_GRAPH, NULL, "min_delay", "Minimum delay" },
     { 6,        0.1,  10,   0, PF_FLOAT | PF_SCALE_LOG | PF_CTL_KNOB | PF_UNIT_MSEC, NULL, "mod_depth", "Modulation depth" },
     { 0.5,     0.01,  20,   0, PF_FLOAT | PF_SCALE_LOG | PF_CTL_KNOB | PF_UNIT_HZ, NULL, "mod_rate", "Modulation rate" },
     { 180,        0, 360,  91, PF_FLOAT | PF_SCALE_LINEAR | PF_CTL_KNOB | PF_UNIT_DEG, NULL, "stereo", "Stereo phase" },

-- 
calf audio plugins packaging