Merge pull request #306 from paulfd/noise-generators-2

Differentiate between gnoise and noise in generators

src/sfizz/Config.h

@@ -78,6 +78,7 @@ namespace config {
     constexpr int filtersPerVoice { 2 };
     constexpr int eqsPerVoice { 3 };
     constexpr int oscillatorsPerVoice { 9 };
+    constexpr float uniformNoiseBounds { 0.25f };
     constexpr float noiseVariance { 0.25f };
     /**
        Minimum interval in frames between recomputations of coefficients of the

src/sfizz/Voice.cpp

@@ -609,8 +609,20 @@ void sfz::Voice::fillWithGenerator(AudioSpan<float> buffer) noexcept
     const auto rightSpan  = buffer.getSpan(1);
 
     if (region->sampleId.filename() == "*noise") {
-        absl::c_generate(leftSpan, noiseDist);
-        absl::c_generate(rightSpan, noiseDist);
+        auto gen = [&]() {
+            return uniformNoiseDist(Random::randomGenerator);
+        };
+        absl::c_generate(leftSpan, gen);
+        absl::c_generate(rightSpan, gen);
+    } else if (region->sampleId.filename() == "*gnoise") {
+        // You need to wrap in a lambda, otherwise generate will
+        // make a copy of the gaussian distribution *along with its state*
+        // leading to periodic behavior....
+        auto gen = [&]() {
+            return gaussianNoiseDist();
+        };
+        absl::c_generate(leftSpan, gen);
+        absl::c_generate(rightSpan, gen);
     } else {
         const auto numFrames = buffer.getNumFrames();
 

src/sfizz/Voice.h

@@ -467,7 +467,8 @@ private:
     Voice* nextSisterVoice { this };
     Voice* previousSisterVoice { this };
 
-    fast_gaussian_generator<float> noiseDist { 0.0f, config::noiseVariance };
+    fast_real_distribution<float> uniformNoiseDist { -config::uniformNoiseBounds, config::uniformNoiseBounds };
+    fast_gaussian_generator<float> gaussianNoiseDist { 0.0f, config::noiseVariance };
 
     ModifierArray<std::vector<Smoother>> modifierSmoothers;
     Smoother gainSmoother;