Thank you Mason and Patrick for your replies.

I understand what you mean, but it seems still hard for me. I'm trying to search for examples using SDL_AllocRW but there are very few pages with examples.

If I look here, it seems that I have to create all those functions (myseekfunction...), but I have not found the meaning of those functions. Do I have to create a read function where feeding the data? In that case, how to do it with curl (or any other way)?

I have also found this, but I don't know (again) how to get the data into the istream.

I don't know how to approach the problem. Could somebody help me to make up my mind with this issue?

Thank you.