mathbase: use sample indices and copy rather than zeroing out

app/node/math/math/mathbase.cpp

@@ -248,8 +248,8 @@ NodeValueTable MathNodeBase::ValueInternal(NodeValueDatabase &value, Operation o
 
     SampleBufferPtr mixed_samples = SampleBuffer::CreateAllocated(samples_a->audio_params(), max_samples);
 
-    // Mix samples that are in both buffers
     for (int i=0;i<mixed_samples->audio_params().channel_count();i++) {
+      // Mix samples that are in both buffers
       for (int j=0;j<min_samples;j++) {
         mixed_samples->data()[i][j] = PerformAll<float, float>(operation, samples_a->data()[i][j], samples_b->data()[i][j]);
       }
@@ -259,9 +259,11 @@ NodeValueTable MathNodeBase::ValueInternal(NodeValueDatabase &value, Operation o
       // Fill in remainder space with 0s
       int remainder = max_samples - min_samples;
 
+      SampleBufferPtr larger_buffer = (max_samples == samples_a->sample_count()) ? samples_a : samples_b;
+
       for (int i=0;i<mixed_samples->audio_params().channel_count();i++) {
-        memset(mixed_samples->data()[i] + min_samples * sizeof(float),
-               0,
+        memcpy(&mixed_samples->data()[i][min_samples],
+               &larger_buffer->data()[i][min_samples],
                remainder * sizeof(float));
       }
     }