Crest factor: 0 instead of NaN on silence

core/src/features/crestfactor.cpp

@@ -28,14 +28,16 @@ void CrestFactor::extract()
     for (int i = 0; i < x_size; ++i) {
         square_sum += x[i] * x[i];
 
-        peak_tmp = abs(x[i]);
+        peak_tmp = std::fabs(x[i]);
         peak_max = peak_tmp > peak_max ? peak_tmp : peak_max;
     }
 
     square_sum  = square_sum / x_size;
     square_root = std::sqrt(square_sum);
 
-    crr_y = peak_max / square_root;
+    // Silence: peak and RMS are both 0 and the ratio would be NaN, which then rides into
+    // every object downstream. Report 0, like the spectral features do with no energy.
+    crr_y = square_root > 0.0 ? peak_max / square_root : 0.0;
 }
 
 void CrestFactor::reset() { _reset_param(); }

docs/releases/max-v0.3.0.md

@@ -43,6 +43,8 @@ First release of Zerr* for Max, as a package for Max 9 on Apple Silicon (arm64,
   silently on the audio thread. (#30)
 - `zerr.combinator~` builds the core combinator for real; before #19 the mode argument was parsed
   and discarded. (#19)
+- `zerr.features~ cf` outputs 0 on silence instead of NaN (0/0), which used to poison every
+  object downstream once the input went quiet.
 
 ## Build and tooling
 

docs/releases/pd-next.md

@@ -11,3 +11,5 @@ since 2026-10-15 only; everything earlier since `v0.2` still has to be enumerate
 - `zerr_features~` says why it refuses a block size instead of printing the two numbers:
   the block must be 1 to 2048 samples, the analysis window, and the sample rate non-zero (#43).
   The help patch documents the limit.
+- `zerr_features~ cf` outputs 0 on silence instead of NaN (0/0), which used to poison every
+  object downstream once the input went quiet.