+/**
+ * Free all string and binary options in obj.
+ */
+void av_opt_free(void *obj);
+
+/**
+ * Check whether a particular flag is set in a flags field.
+ *
+ * @param field_name the name of the flag field option
+ * @param flag_name the name of the flag to check
+ * @return non-zero if the flag is set, zero if the flag isn't set,
+ * isn't of the right type, or the flags field doesn't exist.
+ */
+int av_opt_flag_is_set(void *obj, const char *field_name, const char *flag_name);
+
+/*
+ * Set all the options from a given dictionary on an object.
+ *
+ * @param obj a struct whose first element is a pointer to AVClass
+ * @param options options to process. This dictionary will be freed and replaced
+ * by a new one containing all options not found in obj.
+ * Of course this new dictionary needs to be freed by caller
+ * with av_dict_free().
+ *
+ * @return 0 on success, a negative AVERROR if some option was found in obj,
+ * but could not be set.
+ *
+ * @see av_dict_copy()
+ */
+int av_opt_set_dict(void *obj, struct AVDictionary **options);
+
+/**
+ * @defgroup opt_eval_funcs Evaluating option strings
+ * @{
+ * This group of functions can be used to evaluate option strings
+ * and get numbers out of them. They do the same thing as av_opt_set(),
+ * except the result is written into the caller-supplied pointer.
+ *
+ * @param obj a struct whose first element is a pointer to AVClass.
+ * @param o an option for which the string is to be evaluated.
+ * @param val string to be evaluated.
+ * @param *_out value of the string will be written here.
+ *
+ * @return 0 on success, a negative number on failure.
+ */
+int av_opt_eval_flags (void *obj, const AVOption *o, const char *val, int *flags_out);
+int av_opt_eval_int (void *obj, const AVOption *o, const char *val, int *int_out);
+int av_opt_eval_int64 (void *obj, const AVOption *o, const char *val, int64_t *int64_out);
+int av_opt_eval_float (void *obj, const AVOption *o, const char *val, float *float_out);
+int av_opt_eval_double(void *obj, const AVOption *o, const char *val, double *double_out);
+int av_opt_eval_q (void *obj, const AVOption *o, const char *val, AVRational *q_out);
+/**
+ * @}
+ */
+
+#define AV_OPT_SEARCH_CHILDREN 0x0001 /**< Search in possible children of the
+ given object first. */
+/**
+ * The obj passed to av_opt_find() is fake -- only a double pointer to AVClass
+ * instead of a required pointer to a struct containing AVClass. This is
+ * useful for searching for options without needing to allocate the corresponding
+ * object.
+ */
+#define AV_OPT_SEARCH_FAKE_OBJ 0x0002
+
+/**
+ * Look for an option in an object. Consider only options which
+ * have all the specified flags set.
+ *
+ * @param[in] obj A pointer to a struct whose first element is a
+ * pointer to an AVClass.
+ * Alternatively a double pointer to an AVClass, if
+ * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
+ * @param[in] name The name of the option to look for.
+ * @param[in] unit When searching for named constants, name of the unit
+ * it belongs to.
+ * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
+ * @param search_flags A combination of AV_OPT_SEARCH_*.
+ *
+ * @return A pointer to the option found, or NULL if no option
+ * was found.
+ *
+ * @note Options found with AV_OPT_SEARCH_CHILDREN flag may not be settable
+ * directly with av_set_string3(). Use special calls which take an options
+ * AVDictionary (e.g. avformat_open_input()) to set options found with this
+ * flag.
+ */
+const AVOption *av_opt_find(void *obj, const char *name, const char *unit,
+ int opt_flags, int search_flags);
+
+/**
+ * Look for an option in an object. Consider only options which
+ * have all the specified flags set.
+ *
+ * @param[in] obj A pointer to a struct whose first element is a
+ * pointer to an AVClass.
+ * Alternatively a double pointer to an AVClass, if
+ * AV_OPT_SEARCH_FAKE_OBJ search flag is set.
+ * @param[in] name The name of the option to look for.
+ * @param[in] unit When searching for named constants, name of the unit
+ * it belongs to.
+ * @param opt_flags Find only options with all the specified flags set (AV_OPT_FLAG).
+ * @param search_flags A combination of AV_OPT_SEARCH_*.
+ * @param[out] target_obj if non-NULL, an object to which the option belongs will be
+ * written here. It may be different from obj if AV_OPT_SEARCH_CHILDREN is present
+ * in search_flags. This parameter is ignored if search_flags contain
+ * AV_OPT_SEARCH_FAKE_OBJ.
+ *
+ * @return A pointer to the option found, or NULL if no option
+ * was found.
+ */
+const AVOption *av_opt_find2(void *obj, const char *name, const char *unit,
+ int opt_flags, int search_flags, void **target_obj);
+
+/**
+ * Iterate over all AVOptions belonging to obj.
+ *
+ * @param obj an AVOptions-enabled struct or a double pointer to an
+ * AVClass describing it.
+ * @param prev result of the previous call to av_opt_next() on this object
+ * or NULL
+ * @return next AVOption or NULL
+ */
+const AVOption *av_opt_next(void *obj, const AVOption *prev);
+
+/**
+ * Iterate over AVOptions-enabled children of obj.
+ *
+ * @param prev result of a previous call to this function or NULL
+ * @return next AVOptions-enabled child or NULL
+ */
+void *av_opt_child_next(void *obj, void *prev);
+
+/**
+ * Iterate over potential AVOptions-enabled children of parent.
+ *
+ * @param prev result of a previous call to this function or NULL
+ * @return AVClass corresponding to next potential child or NULL
+ */
+const AVClass *av_opt_child_class_next(const AVClass *parent, const AVClass *prev);
+
+/**
+ * @defgroup opt_set_funcs Option setting functions
+ * @{
+ * Those functions set the field of obj with the given name to value.
+ *
+ * @param[in] obj A struct whose first element is a pointer to an AVClass.
+ * @param[in] name the name of the field to set
+ * @param[in] val The value to set. In case of av_opt_set() if the field is not
+ * of a string type, then the given string is parsed.
+ * SI postfixes and some named scalars are supported.
+ * If the field is of a numeric type, it has to be a numeric or named
+ * scalar. Behavior with more than one scalar and +- infix operators
+ * is undefined.
+ * If the field is of a flags type, it has to be a sequence of numeric
+ * scalars or named flags separated by '+' or '-'. Prefixing a flag
+ * with '+' causes it to be set without affecting the other flags;
+ * similarly, '-' unsets a flag.
+ * @param search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
+ * is passed here, then the option may be set on a child of obj.
+ *
+ * @return 0 if the value has been set, or an AVERROR code in case of
+ * error:
+ * AVERROR_OPTION_NOT_FOUND if no matching option exists
+ * AVERROR(ERANGE) if the value is out of range
+ * AVERROR(EINVAL) if the value is not valid
+ */
+int av_opt_set (void *obj, const char *name, const char *val, int search_flags);
+int av_opt_set_int (void *obj, const char *name, int64_t val, int search_flags);
+int av_opt_set_double(void *obj, const char *name, double val, int search_flags);
+int av_opt_set_q (void *obj, const char *name, AVRational val, int search_flags);
+/**
+ * @}
+ */
+
+/**
+ * @defgroup opt_get_funcs Option getting functions
+ * @{
+ * Those functions get a value of the option with the given name from an object.
+ *
+ * @param[in] obj a struct whose first element is a pointer to an AVClass.
+ * @param[in] name name of the option to get.
+ * @param[in] search_flags flags passed to av_opt_find2. I.e. if AV_OPT_SEARCH_CHILDREN
+ * is passed here, then the option may be found in a child of obj.
+ * @param[out] out_val value of the option will be written here
+ * @return 0 on success, a negative error code otherwise
+ */
+/**
+ * @note the returned string will av_malloc()ed and must be av_free()ed by the caller
+ */
+int av_opt_get (void *obj, const char *name, int search_flags, uint8_t **out_val);
+int av_opt_get_int (void *obj, const char *name, int search_flags, int64_t *out_val);
+int av_opt_get_double(void *obj, const char *name, int search_flags, double *out_val);
+int av_opt_get_q (void *obj, const char *name, int search_flags, AVRational *out_val);
+/**
+ * @}
+ * @}
+ */
+