函数 av_opt_query_ranges 

pub unsafe extern "C" fn av_opt_query_ranges(
    arg1: *mut *mut AVOptionRanges,
    obj: *mut c_void,
    key: *const c_char,
    flags: c_int,
) -> c_int

Get a list of allowed ranges for the given option.

The returned list may depend on other fields in obj like for example profile.

@param flags is a bitmask of flags, undefined flags should not be set and should be ignored AV_OPT_SEARCH_FAKE_OBJ indicates that the obj is a double pointer to a AVClass instead of a full instance AV_OPT_MULTI_COMPONENT_RANGE indicates that function may return more than one component, @see AVOptionRanges

The result must be freed with av_opt_freep_ranges.

@return number of components returned on success, a negative error code otherwise