(Context Adaptive Variable Length Coding) CAVLC in H.264.
This is the CAVLC encoding for H264

-- Context Adaptive Variable Length Coding (CAVLC) encodes all co-efficients
-- from 4x4 (or 2x2) residuals in an efficient way.　It is context dependant in that
-- it uses different tables depending on recent 4x4 encodings (or 2x2 encoding)

-- Input: VIN - value to be encoded in reverse zigzag order (1 per clock)