quartz: Drop packets in the transform filter if in the wrong state.

dlls/quartz/transform.c

@@ -54,6 +54,12 @@ static HRESULT TransformFilter_Sample(LPVOID iface, IMediaSample * pSample)
 
     TRACE("%p %p\n", iface, pSample);
 
+    if (This->state == State_Paused)
+        return S_FALSE;
+
+    if (This->state == State_Stopped)
+        return VFW_E_WRONG_STATE;
+
     return This->pFuncsTable->pfnProcessSampleData(This, pSample);
 }