| /* |
| * Copyright (c) 2016, Alliance for Open Media. All rights reserved |
| * |
| * This source code is subject to the terms of the BSD 2 Clause License and |
| * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License |
| * was not distributed with this source code in the LICENSE file, you can |
| * obtain it at www.aomedia.org/license/software. If the Alliance for Open |
| * Media Patent License 1.0 was not distributed with this source code in the |
| * PATENTS file, you can obtain it at www.aomedia.org/license/patent. |
| */ |
| |
| #include <assert.h> |
| |
| #include "aom/aom_integer.h" |
| |
| #include "aom_ports/mem.h" |
| |
| #include "aom_dsp/aom_dsp_common.h" |
| |
| #include "av1/common/reconinter.h" |
| |
| #define MAX_MASK_VALUE (1 << WEDGE_WEIGHT_BITS) |
| |
| /** |
| * Computes SSE of a compound predictor constructed from 2 fundamental |
| * predictors p0 and p1 using blending with mask. |
| * |
| * r1: Residuals of p1. |
| * (source - p1) |
| * d: Difference of p1 and p0. |
| * (p1 - p0) |
| * m: The blending mask |
| * N: Number of pixels |
| * |
| * 'r1', 'd', and 'm' are contiguous. |
| * |
| * Computes: |
| * Sum((MAX_MASK_VALUE*r1 + mask*d)**2), which is equivalent to: |
| * Sum((mask*r0 + (MAX_MASK_VALUE-mask)*r1)**2), |
| * where r0 is (source - p0), and r1 is (source - p1), which is in turn |
| * is equivalent to: |
| * Sum((source*MAX_MASK_VALUE - (mask*p0 + (MAX_MASK_VALUE-mask)*p1))**2), |
| * which is the SSE of the residuals of the compound predictor scaled up by |
| * MAX_MASK_VALUE**2. |
| * |
| * Note that we clamp the partial term in the loop to 16 bits signed. This is |
| * to facilitate equivalent SIMD implementation. It should have no effect if |
| * residuals are within 16 - WEDGE_WEIGHT_BITS (=10) signed, which always |
| * holds for 8 bit input, and on real input, it should hold practically always, |
| * as residuals are expected to be small. |
| */ |
| uint64_t av1_wedge_sse_from_residuals_c(const int16_t *r1, const int16_t *d, |
| const uint8_t *m, int N) { |
| uint64_t csse = 0; |
| int i; |
| |
| for (i = 0; i < N; i++) { |
| int32_t t = MAX_MASK_VALUE * r1[i] + m[i] * d[i]; |
| t = clamp(t, INT16_MIN, INT16_MAX); |
| csse += t * t; |
| } |
| return ROUND_POWER_OF_TWO(csse, 2 * WEDGE_WEIGHT_BITS); |
| } |
| |
| /** |
| * Choose the mask sign for a compound predictor. |
| * |
| * ds: Difference of the squares of the residuals. |
| * r0**2 - r1**2 |
| * m: The blending mask |
| * N: Number of pixels |
| * limit: Pre-computed threshold value. |
| * MAX_MASK_VALUE/2 * (sum(r0**2) - sum(r1**2)) |
| * |
| * 'ds' and 'm' are contiguous. |
| * |
| * Returns true if the negated mask has lower SSE compared to the positive |
| * mask. Computation is based on: |
| * Sum((mask*r0 + (MAX_MASK_VALUE-mask)*r1)**2) |
| * > |
| * Sum(((MAX_MASK_VALUE-mask)*r0 + mask*r1)**2) |
| * |
| * which can be simplified to: |
| * |
| * Sum(mask*(r0**2 - r1**2)) > MAX_MASK_VALUE/2 * (sum(r0**2) - sum(r1**2)) |
| * |
| * The right hand side does not depend on the mask, and needs to be passed as |
| * the 'limit' parameter. |
| * |
| * After pre-computing (r0**2 - r1**2), which is passed in as 'ds', the left |
| * hand side is simply a scalar product between an int16_t and uint8_t vector. |
| * |
| * Note that for efficiency, ds is stored on 16 bits. Real input residuals |
| * being small, this should not cause a noticeable issue. |
| */ |
| int8_t av1_wedge_sign_from_residuals_c(const int16_t *ds, const uint8_t *m, |
| int N, int64_t limit) { |
| int64_t acc = 0; |
| |
| do { |
| acc += *ds++ * *m++; |
| } while (--N); |
| |
| return acc > limit; |
| } |
| |
| /** |
| * Compute the element-wise difference of the squares of 2 arrays. |
| * |
| * d: Difference of the squares of the inputs: a**2 - b**2 |
| * a: First input array |
| * b: Second input array |
| * N: Number of elements |
| * |
| * 'd', 'a', and 'b' are contiguous. |
| * |
| * The result is saturated to signed 16 bits. |
| */ |
| void av1_wedge_compute_delta_squares_c(int16_t *d, const int16_t *a, |
| const int16_t *b, int N) { |
| int i; |
| |
| for (i = 0; i < N; i++) |
| d[i] = clamp(a[i] * a[i] - b[i] * b[i], INT16_MIN, INT16_MAX); |
| } |