+#if HAVE_ALSA_ASOUNDLIB_H
+# define DEFAULT_BACKEND BACKEND_ALSA
+#elif HAVE_SYS_SOUNDCARD_H || EMPEG_HOST
+# define DEFAULT_BACKEND BACKEND_OSS
+#elif HAVE_COREAUDIO_AUDIOHARDWARE_H
+# define DEFAULT_BACKEND BACKEND_COREAUDIO
+#else
+# error Cannot choose a default backend
+#endif
+