I tried to use the online tool, but I noticed that no matter what I do I always get at least 4x larger overall file size. Could this be a bug? For example, I have 3 files all of them is about 3mb, the resulted rres however is 20mb.
I depends on the type of files and the compression selected but it could happen. rrespacker processes the input files to extract only required data, i.e that implied decompressing images to extract pixel data. If you choose the embedding as RAW option, size should be approximately the same as input files.