-void set_context_opts(void *ctx, void *opts_ctx, int flags, AVCodec *codec);
+/**
+ * Find the '-loglevel' option in the command line args and apply it.
+ */
+void parse_loglevel(int argc, char **argv, const OptionDef *options);
+
+/**
+ * Return index of option opt in argv or 0 if not found.
+ */
+int locate_option(int argc, char **argv, const OptionDef *options,
+ const char *optname);
+
+/**
+ * Check if the given stream matches a stream specifier.
+ *
+ * @param s Corresponding format context.
+ * @param st Stream from s to be checked.
+ * @param spec A stream specifier of the [v|a|s|d]:[\<stream index\>] form.
+ *
+ * @return 1 if the stream matches, 0 if it doesn't, <0 on error
+ */
+int check_stream_specifier(AVFormatContext *s, AVStream *st, const char *spec);