ref: 5680b4517fd30d23e7d70fcffc24cf384ca9d720
parent: a2dfbbd7d69f2991b571090c6b356203dffba523
author: paulwilkins <paulwilkins@google.com>
date: Wed Feb 3 10:37:32 EST 2016
Changes to modified error. The modified error was a derivative of the "coded_error" that was used to allocate bits between different frames on the assumption that the allocation should be linear in terms of this modified error. I.e. a frame with double the modified error score should all things being equal get double the number of bits. The code also included upper and lower caps derived from input VBR parameters. This patch improves the initial calculation of the clip mean error (now called "mean_mod_score" as it is no longer a prediction error) used as the midpoint for the rate distribution function and normalizes the output "modified scores" scores such that 1.0 indicates a frame in the middle of the distribution. The VBR upper and lower caps are then applied directly to a frame's normalized score. This refactoring is intended to make it easier to drop in alternative distribution functions or to base the rate allocation on a corpus wide midpoint (rather than the clip mean). Change-Id: I4fb09de637e93566bfc4e022b2e7d04660817195