Fix bug in StereoWidth, and add test

source/src/node/processors/panning/stereo-width.cpp

@@ -21,11 +21,13 @@ void StereoWidth::process(Buffer &out, int num_frames)
         sample left = this->input->out[0][frame];
         sample right = this->input->out[1][frame];
 
-        left = width * left + (1 - width) * right;
-        right = width * right + (1 - width) * left;
+        // scale width from 0..1
+        width = (width / 2) + 0.5;
+        sample left_out = width * left + (1 - width) * right;
+        sample right_out = (1 - width) * left + width * right;
 
-        out[0][frame] = left;
-        out[1][frame] = right;
+        out[0][frame] = left_out;
+        out[1][frame] = right_out;
     }
 }
 

tests/test_nodes_processors_multichannel.py

@@ -12,4 +12,22 @@ def test_nodes_multichannel_pan(graph):
     b.set_input("pan", 0.0)
     graph.render_subgraph(b, reset=True)
     assert all(b.output_buffer[0] == 0.5 * math.sqrt(0.5))
-    assert all(b.output_buffer[1] == 0.5 * math.sqrt(0.5))
+    assert all(b.output_buffer[1] == 0.5 * math.sqrt(0.5))
+
+def test_nodes_multichannel_width(graph):
+    a = 0.5
+    b = 1.0
+    c = sf.StereoWidth([a, b], 1.0)
+    graph.render_subgraph(c, reset=True)
+    assert all(c.output_buffer[0] == 0.5)
+    assert all(c.output_buffer[1] == 1.0)
+
+    c.set_input("stereo-width", 0.0)
+    graph.render_subgraph(c, reset=True)
+    assert all(c.output_buffer[0] == 0.75)
+    assert all(c.output_buffer[1] == 0.75)
+
+    c.set_input("stereo-width", -1.0)
+    graph.render_subgraph(c, reset=True)
+    assert all(c.output_buffer[0] == 1.0)
+    assert all(c.output_buffer[1] == 0.5)