ref: afee58f2c4159172f5340f2c7d3e8041cfa0eb91
parent: c39cd9235ece2e55f0cc84fb0f9f5e698146ee9c
author: Linfeng Zhang <linfengz@google.com>
date: Tue Sep 12 07:37:04 EDT 2017
Specialize 4 to 3 scaling in vp9_scale_and_extend_frame_c() Scale 3x3 block instead of 16x16 block in each loop. Benefits: 1. Reduced number of different phase_scaler from 16 to 3. Optimization code will be smaller and faster. 2. The maximum phase_scaler drifting will be reduced from 5/16 to 1/24. (The drifting is 1/(3*16) in each step.) BUG=webm:1419 Change-Id: Ibb9242a629ddb03e1ff93b859bece738255e698c