Use Doxygen \todo instead of TODO to have everything at one place.

src/Magnum/Audio/Listener.cpp

@@ -65,7 +65,7 @@ template<UnsignedInt dimensions> void Listener<dimensions>::clean(const MatrixTy
 
     Renderer::setListenerGain(_gain);
 
-    // TODO: velocity
+    /** @todo velocity */
 }
 
 template<UnsignedInt dimensions> void Listener<dimensions>::update(std::initializer_list<std::reference_wrapper<PlayableGroup<dimensions>>> groups) {

src/Magnum/Audio/Playable.h

@@ -149,7 +149,7 @@ template<UnsignedInt dimensions> class Playable: public SceneGraph::AbstractGrou
             _source.setPosition(position);
             _source.setDirection(Vector3::pad(absoluteTransformationMatrix.rotation()*_fwd));
 
-            // TODO: velocity
+            /** @todo velocity */
         }
 
         /* Update the gain of the underlying source to reflect changes in _group and/or _gain.