AnalogTapeModel

commit e72f08bdeebc629c9ea97587d104abfc83b3ee20
parent 1b30b66eb2757e0cdd3d669a6c02613de7a2d5cd
Author: jatinchowdhury18 <jatinchowdhury18@users.noreply.github.com>
Date:   Wed, 13 May 2020 11:05:41 -0700

Fix stability issues related to tanh approx and input range

Diffstat:
M
Plugin/Source/Processors/Hysteresis/HysteresisProcessing.cpp
 | 
6
++----
M
Plugin/Source/Processors/Hysteresis/HysteresisProcessor.cpp
 | 
5
+++++

2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/Plugin/Source/Processors/Hysteresis/HysteresisProcessing.cpp b/Plugin/Source/Processors/Hysteresis/HysteresisProcessing.cpp
@@ -69,7 +69,7 @@ inline float HysteresisProcessing::deriv (float x_n, float x_n1, float x_d_n1)
 inline float HysteresisProcessing::hysteresisFunc (float M, float H, float H_d)
 {
     Q = (H + alpha * M) / a;
-    coth = 1.0f /  dsp::FastMathApproximations::tanh (Q);
+    coth = 1.0f / std::tanh (Q);
     nearZero = Q < 0.001f && Q > -0.001f;
 
     M_diff = M_s * langevin (Q) - M;
@@ -105,11 +105,9 @@ float HysteresisProcessing::process (float H)
 
     float M = M_n1 + k2;
 
-    if (std::isnan (M))
+    if (std::isnan (M) || abs (M) > 20.0f)
     {
         M = 0.0f;
-        H = 0.0f;
-        H_d = 0.0f;
     }
 
     M_n1 = M;
diff --git a/Plugin/Source/Processors/Hysteresis/HysteresisProcessor.cpp b/Plugin/Source/Processors/Hysteresis/HysteresisProcessor.cpp
@@ -150,6 +150,11 @@ void HysteresisProcessor::processBlock (AudioBuffer<float>& buffer, MidiBuffer& 
             fadeBuffer.copyFrom (ch, 0, buffer, ch, 0, buffer.getNumSamples());
     }
 
+    // clip input to +9 dB
+    for (int ch = 0; ch < buffer.getNumChannels(); ++ch)
+        FloatVectorOperations::clip (buffer.getWritePointer (ch),
+            buffer.getWritePointer (ch), -8.0f, 8.0f, buffer.getNumSamples());
+
     dsp::AudioBlock<float> block (buffer);
     dsp::AudioBlock<float> osBlock;