ref: acf5d20ce5811ff8b6eb561f09c5751b25539fb8
parent: a8fbab8697c77dc82013862e0a9c7f82b6402db8
author: Yaowu Xu <yaowu@google.com>
date: Wed Nov 30 11:36:46 EST 2011
added separate entropy context for alt_ref This commit added code to keep track of separate entropy contexts for normal frames and alt ref frames. The underly assumption was that the two type of frames have different entropy characteristics given they typically have quite different quantization levels. By keeping entropy contexts separate, it helps the entropy context distribution to be more closely adapted to each frame type. Tests on derf set showed a good and very consistent gain on all clips on all metrics, avg psnr: 0.89%, overall psnr: 0.84% and ssim 0.93%. http://www.corp.google.com/~yaowu/no_crawl/mulcontext.html Change-Id: I15bc9697f6ff7829042911fe0c62930585d7e65d