[SCM] calf/master: + MultiChorus: change multilfo interface to output value instead of phase (+update multichorus), make scale 1/sqrt(N) instead of 1/N, move scale calculation outside the loop, remove leftover printf

[js at users.alioth.debian.org]

The following commit has been merged in the master branch:
commit b7146740bb399dad9e309bf0d645ba2175a3c3dc
Author: Krzysztof Foltman <wdev at foltman.com>
Date:   Tue Oct 28 19:42:16 2008 +0000

    + MultiChorus: change multilfo interface to output value instead of phase (+update multichorus), make scale 1/sqrt(N) instead of 1/N, move scale calculation outside the loop, remove leftover printf

diff --git a/src/calf/multichorus.h b/src/calf/multichorus.h
index d737cb0..e5b7ef7 100644
--- a/src/calf/multichorus.h
+++ b/src/calf/multichorus.h
@@ -35,21 +35,32 @@ protected:
     enum { Multiplier = (65536 / Voices) << 16 };
     
 public:
-    chorus_phase phase, dphase;
+    /// Current LFO phase
+    chorus_phase phase;
+    /// LFO phase increment
+    chorus_phase dphase;
 
 public:
     inline uint32_t get_voices() const
     {
         return Voices;
     }
-    inline chorus_phase get_phase(uint32_t voice) const {
-        return phase + chorus_phase::from_base(Multiplier * voice);
+    /// Get LFO value for given voice, returns a values in range of [-65536, 65536]
+    inline int get_value(uint32_t voice) {
+        // find this voice's phase (= phase + voice * 360 degrees / number of voices)
+        chorus_phase voice_phase = phase + chorus_phase::from_base(Multiplier * voice);
+        // find table offset
+        unsigned int ipart = voice_phase.ipart();
+        // interpolate (use 14 bits of precision - because the table itself uses 18 bits and the result of multiplication must fit in int32_t)
+        // note, the result is still -65536 .. 65536, it's just interpolated
+        return voice_phase.lerp_by_fract_int<int, 14, int>(sine.data[ipart], sine.data[ipart+1]);
     }
     inline void step() {
         phase += dphase;
     }
     inline T get_scale() const {
-        return 1.0 / Voices;
+        // use sqrt, because some phases will cancel each other - so 1 / N is usually too low
+        return sqrt(1.0 / Voices);
     }
     void reset() {
         phase = 0.f;
@@ -84,7 +95,6 @@ public:
         lfo.dphase = dphase;
     }
     virtual void setup(int sample_rate) {
-        printf("setting sample rate = %d\n", sample_rate);
         modulation_effect::setup(sample_rate);
         delay.reset();
         lfo.reset();
@@ -94,7 +104,8 @@ public:
     template<class OutIter, class InIter>
     void process(OutIter buf_out, InIter buf_in, int nsamples) {
         int mds = min_delay_samples + mod_depth_samples * 1024 + 2*65536;
-        int mdepth = mod_depth_samples;
+        int mdepth = mod_depth_samples; // 1 sample peak-to-peak = mdepth of 32 (this scaling stuff is tricky and may - but shouldn't - be wrong)
+        T scale = lfo.get_scale();
         for (int i=0; i<nsamples; i++) {
             phase += dphase;
             
@@ -106,17 +117,15 @@ public:
             // add up values from all voices, each voice tell its LFO phase and the buffer value is picked at that location
             for (unsigned int v = 0; v < nvoices; v++)
             {
-                chorus_phase phase = lfo.get_phase(v);
-                unsigned int ipart = phase.ipart();
-                int lfo = phase.lerp_by_fract_int<int, 14, int>(sine.data[ipart], sine.data[ipart+1]);
-                int v = mds + (mdepth * lfo >> 6);
+                int lfo_output = lfo.get_value(v);
+                int v = mds + (mdepth * lfo_output >> 6);
                 int ifv = v >> 16;
                 T fd; // signal from delay's output
                 delay.get_interp(fd, ifv, (v & 0xFFFF)*(1.0/65536.0));
                 out += fd;
             }
             T sdry = in * gs_dry.get();
-            T swet = out * gs_wet.get() * lfo.get_scale();
+            T swet = out * gs_wet.get() * scale;
             *buf_out++ = sdry + swet;
             lfo.step();
         }

-- 
calf audio plugins packaging