A digital video signal encoder for coding a block of a digital video signal first converts the block of the digital video signal into a set of quantized transform coefficients having a low and a high frequency zones and scans the set of quantized transform coefficients to produce a first and a second...http://www.google.se/patents/US5640420?utm_source=gb-gplus-sharePatent US5640420 - Variable length coder using two VLC tables
