diff --git a/src/Filter.cpp b/src/Filter.cpp
index df54c67..7fcde3d 100644
--- a/src/Filter.cpp
+++ b/src/Filter.cpp
@@ -28,6 +28,8 @@ float Filter::Process(float in) {
 }
 
 void Filter::Process(std::vector<float>& samples) {
+    // todo: that will not work for ADSR-controlled filter. So, let's calculate all the possible frequency values into array/dictionary
+    // then just lookup for each sample
     calculate_coefficients();
     for (std::size_t i = 0; i < samples.size(); i++) {
         samples[i] = Process(samples[i]);