-# define VLC_THREAD_PRIORITY_INPUT THREAD_PRIORITY_ABOVE_NORMAL
-# define VLC_THREAD_PRIORITY_AUDIO THREAD_PRIORITY_ABOVE_NORMAL
-# define VLC_THREAD_PRIORITY_VIDEO 0
-# define VLC_THREAD_PRIORITY_OUTPUT THREAD_PRIORITY_ABOVE_NORMAL
+# define VLC_THREAD_PRIORITY_INPUT \
+ (IS_WINNT ? THREAD_PRIORITY_TIME_CRITICAL : 0)
+# define VLC_THREAD_PRIORITY_AUDIO \
+ (IS_WINNT ? THREAD_PRIORITY_HIGHEST : 0)
+# define VLC_THREAD_PRIORITY_VIDEO \
+ (IS_WINNT ? 0 : THREAD_PRIORITY_BELOW_NORMAL )
+# define VLC_THREAD_PRIORITY_OUTPUT \
+ (IS_WINNT ? THREAD_PRIORITY_ABOVE_NORMAL : 0)
+# define VLC_THREAD_PRIORITY_HIGHEST \
+ (IS_WINNT ? THREAD_PRIORITY_TIME_CRITICAL : 0)
+
+#elif defined(SYS_BEOS)
+# define VLC_THREAD_PRIORITY_LOW 5
+# define VLC_THREAD_PRIORITY_INPUT 10
+# define VLC_THREAD_PRIORITY_AUDIO 10
+# define VLC_THREAD_PRIORITY_VIDEO 5
+# define VLC_THREAD_PRIORITY_OUTPUT 15