scale.c (2383B)
1 /* 2 * Copyright (c) 2016, Alliance for Open Media. All rights reserved. 3 * 4 * This source code is subject to the terms of the BSD 2 Clause License and 5 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License 6 * was not distributed with this source code in the LICENSE file, you can 7 * obtain it at www.aomedia.org/license/software. If the Alliance for Open 8 * Media Patent License 1.0 was not distributed with this source code in the 9 * PATENTS file, you can obtain it at www.aomedia.org/license/patent. 10 */ 11 12 #include "config/aom_dsp_rtcd.h" 13 #include "config/av1_rtcd.h" 14 15 #include "av1/common/filter.h" 16 #include "av1/common/scale.h" 17 #include "aom_dsp/aom_filter.h" 18 19 static int get_fixed_point_scale_factor(int other_size, int this_size) { 20 // Calculate scaling factor once for each reference frame 21 // and use fixed point scaling factors in decoding and encoding routines. 22 // Hardware implementations can calculate scale factor in device driver 23 // and use multiplication and shifting on hardware instead of division. 24 return ((other_size << REF_SCALE_SHIFT) + this_size / 2) / this_size; 25 } 26 27 // Given the fixed point scale, calculate coarse point scale. 28 static int fixed_point_scale_to_coarse_point_scale(int scale_fp) { 29 return ROUND_POWER_OF_TWO(scale_fp, REF_SCALE_SHIFT - SCALE_SUBPEL_BITS); 30 } 31 32 // Note: x and y are integer precision, mvq4 is q4 precision. 33 MV32 av1_scale_mv(const MV *mvq4, int x, int y, 34 const struct scale_factors *sf) { 35 const int x_off_q4 = av1_scaled_x(x << SUBPEL_BITS, sf); 36 const int y_off_q4 = av1_scaled_y(y << SUBPEL_BITS, sf); 37 const MV32 res = { 38 av1_scaled_y((y << SUBPEL_BITS) + mvq4->row, sf) - y_off_q4, 39 av1_scaled_x((x << SUBPEL_BITS) + mvq4->col, sf) - x_off_q4 40 }; 41 return res; 42 } 43 44 void av1_setup_scale_factors_for_frame(struct scale_factors *sf, int other_w, 45 int other_h, int this_w, int this_h) { 46 if (!valid_ref_frame_size(other_w, other_h, this_w, this_h)) { 47 sf->x_scale_fp = REF_INVALID_SCALE; 48 sf->y_scale_fp = REF_INVALID_SCALE; 49 return; 50 } 51 52 sf->x_scale_fp = get_fixed_point_scale_factor(other_w, this_w); 53 sf->y_scale_fp = get_fixed_point_scale_factor(other_h, this_h); 54 55 sf->x_step_q4 = fixed_point_scale_to_coarse_point_scale(sf->x_scale_fp); 56 sf->y_step_q4 = fixed_point_scale_to_coarse_point_scale(sf->y_scale_fp); 57 }