The Back-end Top module connects quantizer, RLE, Huffman and Byte-Stuffer Modules.
The back-end have a small FSM sitting inside which makes all the modules run parallely.
i.e when Byte-Stuffer sends ready signal to Huffman, Huffman sends ready to RLE, RLE send ready signal to Quantizer.
The Back-end have a input buffer attached which will take data from the front-end, The Buffer have size of 3*64, so that front-end do not have to wait for the back-end to be ready.
Among the backend modules huffman module takes around 80 clock cycles. So, each block have to wait till those cycles finish.