+/**
+ * Return NULL if a threading library has not been enabled.
+ * Used to disable threading functions in AVCodec definitions
+ * when not needed.
+ */
+#if HAVE_THREADS
+# define ONLY_IF_THREADS_ENABLED(x) x
+#else
+# define ONLY_IF_THREADS_ENABLED(x) NULL
+#endif
+
+/**
+ * Log a generic warning message about a missing feature.
+ *
+ * @param[in] avc a pointer to an arbitrary struct of which the first
+ * field is a pointer to an AVClass struct
+ * @param[in] msg string containing the name of the missing feature
+ */
+void avpriv_report_missing_feature(void *avc,
+ const char *msg, ...) av_printf_format(2, 3);
+
+/**
+ * Log a generic warning message about a missing feature.
+ * Additionally request that a sample showcasing the feature be uploaded.
+ *
+ * @param[in] avc a pointer to an arbitrary struct of which the first field is
+ * a pointer to an AVClass struct
+ * @param[in] msg string containing the name of the missing feature
+ */
+void avpriv_request_sample(void *avc,
+ const char *msg, ...) av_printf_format(2, 3);
+