@@ -53,6 +53,9 @@
* question is allowed to access the field. This allows us to extend the
* semantics of those fields without breaking API compatibility.
*
+ * Note: only options with the AV_OPT_FLAG_RUNTIME_PARAM flag can be
+ * modified after the struct is initialized.
+ *
* @section avoptions_scope Scope of AVOptions
*
* AVOptions is designed to support any set of multimedia configuration options
@@ -300,7 +303,7 @@ enum AVOptionType{
#define AV_OPT_FLAG_BSF_PARAM (1 << 8)
/**
- * A generic parameter which can be set by the user at runtime.
+ * A generic parameter which can be set by the user after initialization.
*/
#define AV_OPT_FLAG_RUNTIME_PARAM (1 << 15)
/**
@@ -483,6 +486,9 @@ typedef struct AVOptionRanges {
/**
* Set the values of all AVOption fields to their default values.
*
+ * Note: after a struct is initialized, only options with the
+ * AV_OPT_FLAG_RUNTIME_PARAM flag can be modified.
+ *
* @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
*/
void av_opt_set_defaults(void *s);
@@ -492,6 +498,9 @@ void av_opt_set_defaults(void *s);
* AVOption fields for which (opt->flags & mask) == flags will have their
* default applied to s.
*
+ * Note: after a struct is initialized, only options with the
+ * AV_OPT_FLAG_RUNTIME_PARAM flag can be modified.
+ *
* @param s an AVOption-enabled struct (its first member must be a pointer to AVClass)
* @param mask combination of AV_OPT_FLAG_*
* @param flags combination of AV_OPT_FLAG_*
@@ -661,6 +670,9 @@ enum {
* key. ctx must be an AVClass context, storing is done using
* AVOptions.
*
+ * Note: after a struct is initialized, only options with the
+ * AV_OPT_FLAG_RUNTIME_PARAM flag can be modified.
+ *
* @param opts options string to parse, may be NULL
* @param key_val_sep a 0-terminated list of characters used to
* separate key from value
@@ -679,6 +691,9 @@ int av_set_options_string(void *ctx, const char *opts,
* Parse the key-value pairs list in opts. For each key=value pair found,
* set the value of the corresponding option in ctx.
*
+ * Note: after a struct is initialized, only options with the
+ * AV_OPT_FLAG_RUNTIME_PARAM flag can be modified.
+ *
* @param ctx the AVClass object to set options on
* @param opts the options string, key-value pairs separated by a
* delimiter
@@ -709,6 +724,9 @@ int av_opt_set_from_string(void *ctx, const char *opts,
/**
* Set all the options from a given dictionary on an object.
*
+ * Note: after a struct is initialized, only options with the
+ * AV_OPT_FLAG_RUNTIME_PARAM flag can be modified.
+ *
* @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.
@@ -726,6 +744,9 @@ int av_opt_set_dict(void *obj, struct AVDictionary **options);
/**
* Set all the options from a given dictionary on an object.
*
+ * Note: after a struct is initialized, only options with the
+ * AV_OPT_FLAG_RUNTIME_PARAM flag can be modified.
+ *
* @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.
@@ -764,6 +785,9 @@ int av_opt_copy(void *dest, const void *src);
* @{
* Those functions set the field of obj with the given name to value.
*
+ * Note: after a struct is initialized, only options with the
+ * AV_OPT_FLAG_RUNTIME_PARAM flag can be modified.
+ *
* @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