Timothy B. Terriberry authored Apr 04, 2008 and Jean-Marc Valin committed Apr 05, 2008

This eliminates an extra O(nm) lookups on decode, and reduces the rate control
 from O(nm^2) to O(nm), in addition to eliminating O(m) lookups on both encode
 and decode.
Although the interface is slightly more complex, the internal code is also
 simpler.