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/*
* 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 <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include "aom_dsp/flow_estimation/disflow.h"
#include "aom_dsp/flow_estimation/flow_estimation.h"
#include "aom_dsp/flow_estimation/ransac.h"
#include "aom_scale/yv12config.h"
#include "av1/common/resize.h"
// Number of pyramid levels in disflow computation
#define N_LEVELS 2
// Size of square patches in the disflow dense grid
#define PATCH_SIZE 8
// Center point of square patch
#define PATCH_CENTER ((PATCH_SIZE + 1) >> 1)
// Step size between patches, lower value means greater patch overlap
#define PATCH_STEP 1
// Minimum size of border padding for disflow
#define MIN_PAD 7
// Warp error convergence threshold for disflow
#define DISFLOW_ERROR_TR 0.01
// Max number of iterations if warp convergence is not found
#define DISFLOW_MAX_ITR 10
// Struct for an image pyramid
typedef struct {
int n_levels;
int pad_size;
int has_gradient;
int widths[N_LEVELS];
int heights[N_LEVELS];
int strides[N_LEVELS];
int level_loc[N_LEVELS];
unsigned char *level_buffer;
double *level_dx_buffer;
double *level_dy_buffer;
} ImagePyramid;
// Don't use points around the frame border since they are less reliable
static INLINE int valid_point(int x, int y, int width, int height) {
return (x > (PATCH_SIZE + PATCH_CENTER)) &&
(x < (width - PATCH_SIZE - PATCH_CENTER)) &&
(y > (PATCH_SIZE + PATCH_CENTER)) &&
(y < (height - PATCH_SIZE - PATCH_CENTER));
}
static int determine_disflow_correspondence(int *frm_corners,
int num_frm_corners, double *flow_u,
double *flow_v, int width,
int height, int stride,
double *correspondences) {
int num_correspondences = 0;
int x, y;
for (int i = 0; i < num_frm_corners; ++i) {
x = frm_corners[2 * i];
y = frm_corners[2 * i + 1];
if (valid_point(x, y, width, height)) {
correspondences[4 * num_correspondences] = x;
correspondences[4 * num_correspondences + 1] = y;
correspondences[4 * num_correspondences + 2] = x + flow_u[y * stride + x];
correspondences[4 * num_correspondences + 3] = y + flow_v[y * stride + x];
num_correspondences++;
}
}
return num_correspondences;
}
static double getCubicValue(double p[4], double x) {
return p[1] + 0.5 * x *
(p[2] - p[0] +
x * (2.0 * p[0] - 5.0 * p[1] + 4.0 * p[2] - p[3] +
x * (3.0 * (p[1] - p[2]) + p[3] - p[0])));
}
static void get_subcolumn(unsigned char *ref, double col[4], int stride, int x,
int y_start) {
int i;
for (i = 0; i < 4; ++i) {
col[i] = ref[(i + y_start) * stride + x];
}
}
static double bicubic(unsigned char *ref, double x, double y, int stride) {
double arr[4];
int k;
int i = (int)x;
int j = (int)y;
for (k = 0; k < 4; ++k) {
double arr_temp[4];
get_subcolumn(ref, arr_temp, stride, i + k - 1, j - 1);
arr[k] = getCubicValue(arr_temp, y - j);
}
return getCubicValue(arr, x - i);
}
// Interpolate a warped block using bicubic interpolation when possible
static unsigned char interpolate(unsigned char *ref, double x, double y,
int width, int height, int stride) {
if (x < 0 && y < 0)
return ref[0];
else if (x < 0 && y > height - 1)
return ref[(height - 1) * stride];
else if (x > width - 1 && y < 0)
return ref[width - 1];
else if (x > width - 1 && y > height - 1)
return ref[(height - 1) * stride + (width - 1)];
else if (x < 0) {
int v;
int i = (int)y;
double a = y - i;
if (y > 1 && y < height - 2) {
double arr[4];
get_subcolumn(ref, arr, stride, 0, i - 1);
return clamp((int)(getCubicValue(arr, a) + 0.5), 0, 255);
}
v = (int)(ref[i * stride] * (1 - a) + ref[(i + 1) * stride] * a + 0.5);
return clamp(v, 0, 255);
} else if (y < 0) {
int v;
int j = (int)x;
double b = x - j;
if (x > 1 && x < width - 2) {
double arr[4] = { ref[j - 1], ref[j], ref[j + 1], ref[j + 2] };
return clamp((int)(getCubicValue(arr, b) + 0.5), 0, 255);
}
v = (int)(ref[j] * (1 - b) + ref[j + 1] * b + 0.5);
return clamp(v, 0, 255);
} else if (x > width - 1) {
int v;
int i = (int)y;
double a = y - i;
if (y > 1 && y < height - 2) {
double arr[4];
get_subcolumn(ref, arr, stride, width - 1, i - 1);
return clamp((int)(getCubicValue(arr, a) + 0.5), 0, 255);
}
v = (int)(ref[i * stride + width - 1] * (1 - a) +
ref[(i + 1) * stride + width - 1] * a + 0.5);
return clamp(v, 0, 255);
} else if (y > height - 1) {
int v;
int j = (int)x;
double b = x - j;
if (x > 1 && x < width - 2) {
int row = (height - 1) * stride;
double arr[4] = { ref[row + j - 1], ref[row + j], ref[row + j + 1],
ref[row + j + 2] };
return clamp((int)(getCubicValue(arr, b) + 0.5), 0, 255);
}
v = (int)(ref[(height - 1) * stride + j] * (1 - b) +
ref[(height - 1) * stride + j + 1] * b + 0.5);
return clamp(v, 0, 255);
} else if (x > 1 && y > 1 && x < width - 2 && y < height - 2) {
return clamp((int)(bicubic(ref, x, y, stride) + 0.5), 0, 255);
} else {
int i = (int)y;
int j = (int)x;
double a = y - i;
double b = x - j;
int v = (int)(ref[i * stride + j] * (1 - a) * (1 - b) +
ref[i * stride + j + 1] * (1 - a) * b +
ref[(i + 1) * stride + j] * a * (1 - b) +
ref[(i + 1) * stride + j + 1] * a * b);
return clamp(v, 0, 255);
}
}
// Warps a block using flow vector [u, v] and computes the mse
static double compute_warp_and_error(unsigned char *ref, unsigned char *frm,
int width, int height, int stride, int x,
int y, double u, double v, int16_t *dt) {
int i, j;
unsigned char warped;
double x_w, y_w;
double mse = 0;
int16_t err = 0;
for (i = y; i < y + PATCH_SIZE; ++i)
for (j = x; j < x + PATCH_SIZE; ++j) {
x_w = (double)j + u;
y_w = (double)i + v;
warped = interpolate(ref, x_w, y_w, width, height, stride);
err = warped - frm[j + i * stride];
mse += err * err;
dt[(i - y) * PATCH_SIZE + (j - x)] = err;
}
mse /= (PATCH_SIZE * PATCH_SIZE);
return mse;
}
// Computes the components of the system of equations used to solve for
// a flow vector. This includes:
// 1.) The hessian matrix for optical flow. This matrix is in the
// form of:
//
// M = |sum(dx * dx) sum(dx * dy)|
// |sum(dx * dy) sum(dy * dy)|
//
// 2.) b = |sum(dx * dt)|
// |sum(dy * dt)|
// Where the sums are computed over a square window of PATCH_SIZE.
static INLINE void compute_flow_system(const double *dx, int dx_stride,
const double *dy, int dy_stride,
const int16_t *dt, int dt_stride,
double *M, double *b) {
for (int i = 0; i < PATCH_SIZE; i++) {
for (int j = 0; j < PATCH_SIZE; j++) {
M[0] += dx[i * dx_stride + j] * dx[i * dx_stride + j];
M[1] += dx[i * dx_stride + j] * dy[i * dy_stride + j];
M[3] += dy[i * dy_stride + j] * dy[i * dy_stride + j];
b[0] += dx[i * dx_stride + j] * dt[i * dt_stride + j];
b[1] += dy[i * dy_stride + j] * dt[i * dt_stride + j];
}
}
M[2] = M[1];
}
// Solves a general Mx = b where M is a 2x2 matrix and b is a 2x1 matrix
static INLINE void solve_2x2_system(const double *M, const double *b,
double *output_vec) {
double M_0 = M[0];
double M_3 = M[3];
double det = (M_0 * M_3) - (M[1] * M[2]);
if (det < 1e-5) {
// Handle singular matrix
// TODO(sarahparker) compare results using pseudo inverse instead
M_0 += 1e-10;
M_3 += 1e-10;
det = (M_0 * M_3) - (M[1] * M[2]);
}
const double det_inv = 1 / det;
const double mult_b0 = det_inv * b[0];
const double mult_b1 = det_inv * b[1];
output_vec[0] = M_3 * mult_b0 - M[1] * mult_b1;
output_vec[1] = -M[2] * mult_b0 + M_0 * mult_b1;
}
/*
static INLINE void image_difference(const uint8_t *src, int src_stride,
const uint8_t *ref, int ref_stride,
int16_t *dst, int dst_stride, int height,
int width) {
const int block_unit = 8;
// Take difference in 8x8 blocks to make use of optimized diff function
for (int i = 0; i < height; i += block_unit) {
for (int j = 0; j < width; j += block_unit) {
aom_subtract_block(block_unit, block_unit, dst + i * dst_stride + j,
dst_stride, src + i * src_stride + j, src_stride,
ref + i * ref_stride + j, ref_stride);
}
}
}
*/
static INLINE void convolve_2d_sobel_y(const uint8_t *src, int src_stride,
double *dst, int dst_stride, int w,
int h, int dir, double norm) {
int16_t im_block[(MAX_SB_SIZE + MAX_FILTER_TAP - 1) * MAX_SB_SIZE];
DECLARE_ALIGNED(256, static const int16_t, sobel_a[3]) = { 1, 0, -1 };
DECLARE_ALIGNED(256, static const int16_t, sobel_b[3]) = { 1, 2, 1 };
const int taps = 3;
int im_h = h + taps - 1;
int im_stride = w;
const int fo_vert = 1;
const int fo_horiz = 1;
// horizontal filter
const uint8_t *src_horiz = src - fo_vert * src_stride;
const int16_t *x_filter = dir ? sobel_a : sobel_b;
for (int y = 0; y < im_h; ++y) {
for (int x = 0; x < w; ++x) {
int16_t sum = 0;
for (int k = 0; k < taps; ++k) {
sum += x_filter[k] * src_horiz[y * src_stride + x - fo_horiz + k];
}
im_block[y * im_stride + x] = sum;
}
}
// vertical filter
int16_t *src_vert = im_block + fo_vert * im_stride;
const int16_t *y_filter = dir ? sobel_b : sobel_a;
for (int y = 0; y < h; ++y) {
for (int x = 0; x < w; ++x) {
int16_t sum = 0;
for (int k = 0; k < taps; ++k) {
sum += y_filter[k] * src_vert[(y - fo_vert + k) * im_stride + x];
}
dst[y * dst_stride + x] = sum * norm;
}
}
}
// Compute an image gradient using a sobel filter.
// If dir == 1, compute the x gradient. If dir == 0, compute y. This function
// assumes the images have been padded so that they can be processed in units
// of 8.
static INLINE void sobel_xy_image_gradient(const uint8_t *src, int src_stride,
double *dst, int dst_stride,
int height, int width, int dir) {
double norm = 1.0;
// TODO(sarahparker) experiment with doing this over larger block sizes
const int block_unit = 8;
// Filter in 8x8 blocks to eventually make use of optimized convolve function
for (int i = 0; i < height; i += block_unit) {
for (int j = 0; j < width; j += block_unit) {
convolve_2d_sobel_y(src + i * src_stride + j, src_stride,
dst + i * dst_stride + j, dst_stride, block_unit,
block_unit, dir, norm);
}
}
}
static void free_pyramid(ImagePyramid *pyr) {
aom_free(pyr->level_buffer);
if (pyr->has_gradient) {
aom_free(pyr->level_dx_buffer);
aom_free(pyr->level_dy_buffer);
}
aom_free(pyr);
}
static ImagePyramid *alloc_pyramid(int width, int height, int pad_size,
int compute_gradient) {
ImagePyramid *pyr = aom_calloc(1, sizeof(*pyr));
if (!pyr) return NULL;
pyr->has_gradient = compute_gradient;
// 2 * width * height is the upper bound for a buffer that fits
// all pyramid levels + padding for each level
const int buffer_size = sizeof(*pyr->level_buffer) * 2 * width * height +
(width + 2 * pad_size) * 2 * pad_size * N_LEVELS;
pyr->level_buffer = aom_malloc(buffer_size);
if (!pyr->level_buffer) {
free_pyramid(pyr);
return NULL;
}
memset(pyr->level_buffer, 0, buffer_size);
if (compute_gradient) {
const int gradient_size =
sizeof(*pyr->level_dx_buffer) * 2 * width * height +
(width + 2 * pad_size) * 2 * pad_size * N_LEVELS;
pyr->level_dx_buffer = aom_calloc(1, gradient_size);
pyr->level_dy_buffer = aom_calloc(1, gradient_size);
if (!(pyr->level_dx_buffer && pyr->level_dy_buffer)) {
free_pyramid(pyr);
return NULL;
}
}
return pyr;
}
static INLINE void update_level_dims(ImagePyramid *frm_pyr, int level) {
frm_pyr->widths[level] = frm_pyr->widths[level - 1] >> 1;
frm_pyr->heights[level] = frm_pyr->heights[level - 1] >> 1;
frm_pyr->strides[level] = frm_pyr->widths[level] + 2 * frm_pyr->pad_size;
// Point the beginning of the next level buffer to the correct location inside
// the padded border
frm_pyr->level_loc[level] =
frm_pyr->level_loc[level - 1] +
frm_pyr->strides[level - 1] *
(2 * frm_pyr->pad_size + frm_pyr->heights[level - 1]);
}
// Compute coarse to fine pyramids for a frame
static void compute_flow_pyramids(unsigned char *frm, const int frm_width,
const int frm_height, const int frm_stride,
int n_levels, int pad_size, int compute_grad,
ImagePyramid *frm_pyr) {
int cur_width, cur_height, cur_stride, cur_loc;
assert((frm_width >> n_levels) > 0);
assert((frm_height >> n_levels) > 0);
// Initialize first level
frm_pyr->n_levels = n_levels;
frm_pyr->pad_size = pad_size;
frm_pyr->widths[0] = frm_width;
frm_pyr->heights[0] = frm_height;
frm_pyr->strides[0] = frm_width + 2 * frm_pyr->pad_size;
// Point the beginning of the level buffer to the location inside
// the padded border
frm_pyr->level_loc[0] =
frm_pyr->strides[0] * frm_pyr->pad_size + frm_pyr->pad_size;
// This essentially copies the original buffer into the pyramid buffer
// without the original padding
av1_resize_plane(frm, frm_height, frm_width, frm_stride,
frm_pyr->level_buffer + frm_pyr->level_loc[0],
frm_pyr->heights[0], frm_pyr->widths[0],
frm_pyr->strides[0]);
if (compute_grad) {
cur_width = frm_pyr->widths[0];
cur_height = frm_pyr->heights[0];
cur_stride = frm_pyr->strides[0];
cur_loc = frm_pyr->level_loc[0];
assert(frm_pyr->has_gradient && frm_pyr->level_dx_buffer != NULL &&
frm_pyr->level_dy_buffer != NULL);
// Computation x gradient
sobel_xy_image_gradient(frm_pyr->level_buffer + cur_loc, cur_stride,
frm_pyr->level_dx_buffer + cur_loc, cur_stride,
cur_height, cur_width, 1);
// Computation y gradient
sobel_xy_image_gradient(frm_pyr->level_buffer + cur_loc, cur_stride,
frm_pyr->level_dy_buffer + cur_loc, cur_stride,
cur_height, cur_width, 0);
}
// Start at the finest level and resize down to the coarsest level
for (int level = 1; level < n_levels; ++level) {
update_level_dims(frm_pyr, level);
cur_width = frm_pyr->widths[level];
cur_height = frm_pyr->heights[level];
cur_stride = frm_pyr->strides[level];
cur_loc = frm_pyr->level_loc[level];
av1_resize_plane(frm_pyr->level_buffer + frm_pyr->level_loc[level - 1],
frm_pyr->heights[level - 1], frm_pyr->widths[level - 1],
frm_pyr->strides[level - 1],
frm_pyr->level_buffer + cur_loc, cur_height, cur_width,
cur_stride);
if (compute_grad) {
assert(frm_pyr->has_gradient && frm_pyr->level_dx_buffer != NULL &&
frm_pyr->level_dy_buffer != NULL);
// Computation x gradient
sobel_xy_image_gradient(frm_pyr->level_buffer + cur_loc, cur_stride,
frm_pyr->level_dx_buffer + cur_loc, cur_stride,
cur_height, cur_width, 1);
// Computation y gradient
sobel_xy_image_gradient(frm_pyr->level_buffer + cur_loc, cur_stride,
frm_pyr->level_dy_buffer + cur_loc, cur_stride,
cur_height, cur_width, 0);
}
}
}
static INLINE void compute_flow_at_point(unsigned char *frm, unsigned char *ref,
double *dx, double *dy, int x, int y,
int width, int height, int stride,
double *u, double *v) {
double M[4] = { 0 };
double b[2] = { 0 };
double tmp_output_vec[2] = { 0 };
double error = 0;
int16_t dt[PATCH_SIZE * PATCH_SIZE];
double o_u = *u;
double o_v = *v;
for (int itr = 0; itr < DISFLOW_MAX_ITR; itr++) {
error = compute_warp_and_error(ref, frm, width, height, stride, x, y, *u,
*v, dt);
if (error <= DISFLOW_ERROR_TR) break;
compute_flow_system(dx, stride, dy, stride, dt, PATCH_SIZE, M, b);
solve_2x2_system(M, b, tmp_output_vec);
*u += tmp_output_vec[0];
*v += tmp_output_vec[1];
}
if (fabs(*u - o_u) > PATCH_SIZE || fabs(*v - o_u) > PATCH_SIZE) {
*u = o_u;
*v = o_v;
}
}
// make sure flow_u and flow_v start at 0
static bool compute_flow_field(ImagePyramid *frm_pyr, ImagePyramid *ref_pyr,
double *flow_u, double *flow_v) {
int cur_width, cur_height, cur_stride, cur_loc, patch_loc, patch_center;
double *u_upscale =
aom_malloc(frm_pyr->strides[0] * frm_pyr->heights[0] * sizeof(*flow_u));
double *v_upscale =
aom_malloc(frm_pyr->strides[0] * frm_pyr->heights[0] * sizeof(*flow_v));
if (!(u_upscale && v_upscale)) {
aom_free(u_upscale);
aom_free(v_upscale);
return false;
}
assert(frm_pyr->n_levels == ref_pyr->n_levels);
// Compute flow field from coarsest to finest level of the pyramid
for (int level = frm_pyr->n_levels - 1; level >= 0; --level) {
cur_width = frm_pyr->widths[level];
cur_height = frm_pyr->heights[level];
cur_stride = frm_pyr->strides[level];
cur_loc = frm_pyr->level_loc[level];
for (int i = PATCH_SIZE; i < cur_height - PATCH_SIZE; i += PATCH_STEP) {
for (int j = PATCH_SIZE; j < cur_width - PATCH_SIZE; j += PATCH_STEP) {
patch_loc = i * cur_stride + j;
patch_center = patch_loc + PATCH_CENTER * cur_stride + PATCH_CENTER;
compute_flow_at_point(frm_pyr->level_buffer + cur_loc,
ref_pyr->level_buffer + cur_loc,
frm_pyr->level_dx_buffer + cur_loc + patch_loc,
frm_pyr->level_dy_buffer + cur_loc + patch_loc, j,
i, cur_width, cur_height, cur_stride,
flow_u + patch_center, flow_v + patch_center);
}
}
// TODO(sarahparker) Replace this with upscale function in resize.c
if (level > 0) {
int h_upscale = frm_pyr->heights[level - 1];
int w_upscale = frm_pyr->widths[level - 1];
int s_upscale = frm_pyr->strides[level - 1];
for (int i = 0; i < h_upscale; ++i) {
for (int j = 0; j < w_upscale; ++j) {
u_upscale[j + i * s_upscale] =
flow_u[(int)(j >> 1) + (int)(i >> 1) * cur_stride];
v_upscale[j + i * s_upscale] =
flow_v[(int)(j >> 1) + (int)(i >> 1) * cur_stride];
}
}
memcpy(flow_u, u_upscale,
frm_pyr->strides[0] * frm_pyr->heights[0] * sizeof(*flow_u));
memcpy(flow_v, v_upscale,
frm_pyr->strides[0] * frm_pyr->heights[0] * sizeof(*flow_v));
}
}
aom_free(u_upscale);
aom_free(v_upscale);
return true;
}
int av1_compute_global_motion_disflow_based(
TransformationType type, unsigned char *frm_buffer, int frm_width,
int frm_height, int frm_stride, int *frm_corners, int num_frm_corners,
YV12_BUFFER_CONFIG *ref, int bit_depth, int *num_inliers_by_motion,
MotionModel *params_by_motion, int num_motions) {
unsigned char *ref_buffer = ref->y_buffer;
const int ref_width = ref->y_width;
const int ref_height = ref->y_height;
const int pad_size = AOMMAX(PATCH_SIZE, MIN_PAD);
int num_correspondences;
double *correspondences;
RansacFuncDouble ransac = av1_get_ransac_double_prec_type(type);
assert(frm_width == ref_width);
assert(frm_height == ref_height);
// Ensure the number of pyramid levels will work with the frame resolution
const int msb =
frm_width < frm_height ? get_msb(frm_width) : get_msb(frm_height);
const int n_levels = AOMMIN(msb, N_LEVELS);
if (ref->flags & YV12_FLAG_HIGHBITDEPTH) {
ref_buffer = av1_downconvert_frame(ref, bit_depth);
}
// TODO(sarahparker) We will want to do the source pyramid computation
// outside of this function so it doesn't get recomputed for every
// reference. We also don't need to compute every pyramid level for the
// reference in advance, since lower levels can be overwritten once their
// flow field is computed and upscaled. I'll add these optimizations
// once the full implementation is working.
// Allocate frm image pyramids
int compute_gradient = 1;
ImagePyramid *frm_pyr =
alloc_pyramid(frm_width, frm_height, pad_size, compute_gradient);
if (!frm_pyr) return 0;
compute_flow_pyramids(frm_buffer, frm_width, frm_height, frm_stride, n_levels,
pad_size, compute_gradient, frm_pyr);
// Allocate ref image pyramids
compute_gradient = 0;
ImagePyramid *ref_pyr =
alloc_pyramid(ref_width, ref_height, pad_size, compute_gradient);
if (!ref_pyr) {
free_pyramid(frm_pyr);
return 0;
}
compute_flow_pyramids(ref_buffer, ref_width, ref_height, ref->y_stride,
n_levels, pad_size, compute_gradient, ref_pyr);
int ret = 0;
double *flow_u =
aom_malloc(frm_pyr->strides[0] * frm_pyr->heights[0] * sizeof(*flow_u));
double *flow_v =
aom_malloc(frm_pyr->strides[0] * frm_pyr->heights[0] * sizeof(*flow_v));
if (!(flow_u && flow_v)) goto Error;
memset(flow_u, 0,
frm_pyr->strides[0] * frm_pyr->heights[0] * sizeof(*flow_u));
memset(flow_v, 0,
frm_pyr->strides[0] * frm_pyr->heights[0] * sizeof(*flow_v));
if (!compute_flow_field(frm_pyr, ref_pyr, flow_u, flow_v)) goto Error;
// find correspondences between the two images using the flow field
correspondences = aom_malloc(num_frm_corners * 4 * sizeof(*correspondences));
if (!correspondences) goto Error;
num_correspondences = determine_disflow_correspondence(
frm_corners, num_frm_corners, flow_u, flow_v, frm_width, frm_height,
frm_pyr->strides[0], correspondences);
ransac(correspondences, num_correspondences, num_inliers_by_motion,
params_by_motion, num_motions);
// Set num_inliers = 0 for motions with too few inliers so they are ignored.
for (int i = 0; i < num_motions; ++i) {
if (num_inliers_by_motion[i] < MIN_INLIER_PROB * num_correspondences) {
num_inliers_by_motion[i] = 0;
}
}
// Return true if any one of the motions has inliers.
for (int i = 0; i < num_motions; ++i) {
if (num_inliers_by_motion[i] > 0) {
ret = 1;
break;
}
}
aom_free(correspondences);
Error:
free_pyramid(frm_pyr);
free_pyramid(ref_pyr);
aom_free(flow_u);
aom_free(flow_v);
return ret;
}