Suricata

I want to extract the regular matching content and then base64 decode it.

alert http any any -> any any (msg:"test";flow:from_client,established;http.request_body;pcrexform:"#(\w{8})#";base64_decode:bytes 4,offset 0 ;base64_data;conten:"test";

But,it reported a erro : previous transforms not consumed (list: 2, transform_cnt 1)

I found the reason,This is because base64_decode cannot be used with Transformations like pcrexform;
So I can only add pcre:"/./"; before base64_decode . But this pcre:"/./"; is meaningless.

alert http any any -> any any (msg:"test";flow:from_client,established;http.request_body;pcrexform:"#(\w{8})#";pcre:"/./";base64_decode:bytes 4,offset 0 ;base64_data;conten:"test";