allow for stereo input (unused, though)

src/plugin.zig

@@ -72,8 +72,14 @@ pub const RunContext = struct {
             return ImageError.InstantiateFail;
         }
 
+        // we allocate []f32 with size 2 to account for stereo plugins, however
+        // we only use &in_buf[0] and &out_buf[0], and don't use the
+        // (supposedly) right side of neither input or output.
+        var in_buf = try allocator.alloc(f32, 2);
+        std.mem.secureZero(f32, in_buf);
+
         return RunContext{
-            .in_buf = try allocator.alloc(f32, 1),
+            .in_buf = in_buf,
             .out_buf = try allocator.alloc(f32, 2),
             .instance = instance.?,
         };