tree f9cbe31723180a87b78dd362ace541ec7386a29b
parent aac2c12663dc3b7aec16436612c4d3cd3d589001
author Yaowu Xu <yaowu@google.com> 1314817318 -0700
committer Yaowu Xu <yaowu@google.com> 1316215999 -0700

enable selecting&transmitting to for intra mode entropy

This commit added a 3 bit index to the bitstream, the index is used to
look into the intra mode coding entropy context table. The commit uses
the mode stats to calculate the cost of transmitting modes using 8
possible entropy distributions, and selects the distribution that
provides the lowest cost to do the actual mode coding.

Initial test show this provides additional .2%~.3% gain over quantizer
adaptive intra mode coding. So the adaptive intra mode coding provides
a total of .5%(psnr) to .6% gain(ssim) combined for all-key-encoding

To build and test, configure with
--enable-experimental --enable-qimode

Change-Id: I7c41cd8bfb352bc1fe7c5da1848a58faea5ed74a