813c6c3925
This patch expands the set of prev contexts used for video coding from 3 to 4. There is a small improvement of the order of 0.08% for derf and 0.15% on the HD set. The tests were rerun after the various merges last week. There are two columns in each test - the first are the results with the mbskip change, and the second with expanded contexts added on top of that. Derf: http://www.corp.google.com/~debargha/vp8_results/explibvpx_newentropy_expcontext.html HD: http://www.corp.google.com/~debargha/vp8_results/explibvpx_hd_newentropy_expcontext.html Rebased. Broke up 80 char lines. Change-Id: I82d2e72d054e530cbf5ce9aa0e6d85c582965675