Check if given option is set to its default value.
Options o must belong to the obj. This function must not be called to check child's options state.
@see av_opt_is_set_to_default_by_name().
@param obj AVClass object to check option on
@param o option to be checked
@return >0 when option is set to its default,
0 when option is not set its default,
<0 on error
Check if given option is set to its default value.
Options o must belong to the obj. This function must not be called to check child's options state. @see av_opt_is_set_to_default_by_name().
@param obj AVClass object to check option on @param o option to be checked @return >0 when option is set to its default, 0 when option is not set its default, <0 on error