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aomedia / aom / 6f5569f30cf3353da7bbba255af0d07f8a9fa062 / . / av1 / encoder / bgsprite.c
blob: e66736e462e91b2c4b4870d87016c5eca56b412f [file] [log] [blame]
/*
* Copyright (c) 2017, 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.
*/
#define _POSIX_C_SOURCE 200112L // rand_r()
#include <assert.h>
#include <float.h>
#include <limits.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>
#include "av1/encoder/bgsprite.h"
#include "aom_mem/aom_mem.h"
#include "./aom_scale_rtcd.h"
#include "av1/common/mv.h"
#include "av1/common/warped_motion.h"
#include "av1/encoder/encoder.h"
#include "av1/encoder/global_motion.h"
#include "av1/encoder/mathutils.h"
#include "av1/encoder/temporal_filter.h"
/* Blending Modes:
* 0 = Median
* 1 = Mean
*/
#define BGSPRITE_BLENDING_MODE 1
// Enable removal of outliers from mean blending mode.
#if BGSPRITE_BLENDING_MODE == 1
#define BGSPRITE_MEAN_REMOVE_OUTLIERS 0
#endif // BGSPRITE_BLENDING_MODE == 1
/* Interpolation for panorama alignment sampling:
* 0 = Nearest neighbor
* 1 = Bilinear
*/
#define BGSPRITE_INTERPOLATION 0
// Enable turning off bgsprite from firstpass metrics in define_gf_group.
#define BGSPRITE_ENABLE_METRICS 1
// Enable foreground/backgrond segmentation and combine with temporal filter.
#define BGSPRITE_ENABLE_SEGMENTATION 1
// Enable alignment using global motion.
#define BGSPRITE_ENABLE_GME 0
// Block size for foreground mask.
#define BGSPRITE_MASK_BLOCK_SIZE 4
typedef struct {
#if CONFIG_HIGHBITDEPTH
uint16_t y;
uint16_t u;
uint16_t v;
#else
uint8_t y;
uint8_t u;
uint8_t v;
#endif // CONFIG_HIGHBITDEPTH
uint8_t exists;
} YuvPixel;
typedef struct {
int curr_model;
double mean[2];
double var[2];
int age[2];
double u_mean[2];
double v_mean[2];
#if CONFIG_HIGHBITDEPTH
uint16_t y;
uint16_t u;
uint16_t v;
#else
uint8_t y;
uint8_t u;
uint8_t v;
#endif // CONFIG_HIGHBITDEPTH
double final_var;
} YuvPixelGaussian;
// Maps to convert from matrix form to param vector form.
static const int params_to_matrix_map[] = { 2, 3, 0, 4, 5, 1, 6, 7 };
static const int matrix_to_params_map[] = { 2, 5, 0, 1, 3, 4, 6, 7 };
// Convert the parameter array to a 3x3 matrix form.
static void params_to_matrix(const double *const params, double *target) {
for (int i = 0; i < MAX_PARAMDIM - 1; i++) {
assert(params_to_matrix_map[i] < MAX_PARAMDIM - 1);
target[i] = params[params_to_matrix_map[i]];
}
target[8] = 1;
}
// Convert a 3x3 matrix to a parameter array form.
static void matrix_to_params(const double *const matrix, double *target) {
for (int i = 0; i < MAX_PARAMDIM - 1; i++) {
assert(matrix_to_params_map[i] < MAX_PARAMDIM - 1);
target[i] = matrix[matrix_to_params_map[i]];
}
}
#define TRANSFORM_MAT_DIM 3
// Do matrix multiplication on params.
static void multiply_params(double *const m1, double *const m2,
double *target) {
double m1_matrix[MAX_PARAMDIM];
double m2_matrix[MAX_PARAMDIM];
double result[MAX_PARAMDIM];
params_to_matrix(m1, m1_matrix);
params_to_matrix(m2, m2_matrix);
multiply_mat(m2_matrix, m1_matrix, result, TRANSFORM_MAT_DIM,
TRANSFORM_MAT_DIM, TRANSFORM_MAT_DIM);
matrix_to_params(result, target);
}
// Finds x and y limits of a single transformed image.
// Width and height are the size of the input video.
static void find_frame_limit(int width, int height,
const double *const transform, int *x_min,
int *x_max, int *y_min, int *y_max) {
double transform_matrix[MAX_PARAMDIM];
double xy_matrix[3] = { 0, 0, 1 };
double uv_matrix[3] = { 0 };
// Macro used to update frame limits based on transformed coordinates.
#define UPDATELIMITS(u, v, x_min, x_max, y_min, y_max) \
{ \
if ((int)ceil(u) > *x_max) { \
*x_max = (int)ceil(u); \
} \
if ((int)floor(u) < *x_min) { \
*x_min = (int)floor(u); \
} \
if ((int)ceil(v) > *y_max) { \
*y_max = (int)ceil(v); \
} \
if ((int)floor(v) < *y_min) { \
*y_min = (int)floor(v); \
} \
}
params_to_matrix(transform, transform_matrix);
xy_matrix[0] = 0;
xy_matrix[1] = 0;
multiply_mat(transform_matrix, xy_matrix, uv_matrix, TRANSFORM_MAT_DIM,
TRANSFORM_MAT_DIM, 1);
*x_max = (int)ceil(uv_matrix[0]);
*x_min = (int)floor(uv_matrix[0]);
*y_max = (int)ceil(uv_matrix[1]);
*y_min = (int)floor(uv_matrix[1]);
xy_matrix[0] = width - 1;
xy_matrix[1] = 0;
multiply_mat(transform_matrix, xy_matrix, uv_matrix, TRANSFORM_MAT_DIM,
TRANSFORM_MAT_DIM, 1);
UPDATELIMITS(uv_matrix[0], uv_matrix[1], x_min, x_max, y_min, y_max);
xy_matrix[0] = width - 1;
xy_matrix[1] = height - 1;
multiply_mat(transform_matrix, xy_matrix, uv_matrix, TRANSFORM_MAT_DIM,
TRANSFORM_MAT_DIM, 1);
UPDATELIMITS(uv_matrix[0], uv_matrix[1], x_min, x_max, y_min, y_max);
xy_matrix[0] = 0;
xy_matrix[1] = height - 1;
multiply_mat(transform_matrix, xy_matrix, uv_matrix, TRANSFORM_MAT_DIM,
TRANSFORM_MAT_DIM, 1);
UPDATELIMITS(uv_matrix[0], uv_matrix[1], x_min, x_max, y_min, y_max);
#undef UPDATELIMITS
}
// Finds x and y limits for arrays. Also finds the overall max and minimums
static void find_limits(int width, int height, const double **const params,
int num_frames, int *x_min, int *x_max, int *y_min,
int *y_max, int *pano_x_min, int *pano_x_max,
int *pano_y_min, int *pano_y_max) {
*pano_x_max = INT_MIN;
*pano_x_min = INT_MAX;
*pano_y_max = INT_MIN;
*pano_y_min = INT_MAX;
for (int i = 0; i < num_frames; ++i) {
find_frame_limit(width, height, (const double *const)params[i], &x_min[i],
&x_max[i], &y_min[i], &y_max[i]);
if (x_max[i] > *pano_x_max) {
*pano_x_max = x_max[i];
}
if (x_min[i] < *pano_x_min) {
*pano_x_min = x_min[i];
}
if (y_max[i] > *pano_y_max) {
*pano_y_max = y_max[i];
}
if (y_min[i] < *pano_y_min) {
*pano_y_min = y_min[i];
}
}
}
// Inverts a 3x3 matrix that is in the parameter form.
static void invert_params(const double *const params, double *target) {
double temp[MAX_PARAMDIM] = { 0 };
params_to_matrix(params, temp);
// Find determinant of matrix (expansion by minors).
const double det = temp[0] * ((temp[4] * temp[8]) - (temp[5] * temp[7])) -
temp[1] * ((temp[3] * temp[8]) - (temp[5] * temp[6])) +
temp[2] * ((temp[3] * temp[7]) - (temp[4] * temp[6]));
assert(det != 0);
// inverse is transpose of cofactor * 1/det.
double inverse[MAX_PARAMDIM] = { 0 };
inverse[0] = (temp[4] * temp[8] - temp[7] * temp[5]) / det;
inverse[1] = (temp[2] * temp[7] - temp[1] * temp[8]) / det;
inverse[2] = (temp[1] * temp[5] - temp[2] * temp[4]) / det;
inverse[3] = (temp[5] * temp[6] - temp[3] * temp[8]) / det;
inverse[4] = (temp[0] * temp[8] - temp[2] * temp[6]) / det;
inverse[5] = (temp[3] * temp[2] - temp[0] * temp[5]) / det;
inverse[6] = (temp[3] * temp[7] - temp[6] * temp[4]) / det;
inverse[7] = (temp[6] * temp[1] - temp[0] * temp[7]) / det;
inverse[8] = (temp[0] * temp[4] - temp[3] * temp[1]) / det;
matrix_to_params(inverse, target);
}
static void build_image_stack(YV12_BUFFER_CONFIG **const frames,
const int num_frames, const double **const params,
const int *const x_min, const int *const x_max,
const int *const y_min, const int *const y_max,
int pano_x_min, int pano_y_min,
YuvPixel ***img_stack) {
// Re-sample images onto panorama (pre-filtering).
const int x_offset = -pano_x_min;
const int y_offset = -pano_y_min;
const int frame_width = frames[0]->y_width;
const int frame_height = frames[0]->y_height;
for (int i = 0; i < num_frames; ++i) {
// Find transforms from panorama coordinate system back to single image
// coordinate system for sampling.
int transformed_width = x_max[i] - x_min[i] + 1;
int transformed_height = y_max[i] - y_min[i] + 1;
double transform_matrix[MAX_PARAMDIM];
double transform_params[MAX_PARAMDIM - 1];
invert_params(params[i], transform_params);
params_to_matrix(transform_params, transform_matrix);
#if CONFIG_HIGHBITDEPTH
const uint16_t *y_buffer16 = CONVERT_TO_SHORTPTR(frames[i]->y_buffer);
const uint16_t *u_buffer16 = CONVERT_TO_SHORTPTR(frames[i]->u_buffer);
const uint16_t *v_buffer16 = CONVERT_TO_SHORTPTR(frames[i]->v_buffer);
#endif // CONFIG_HIGHBITDEPTH
for (int y = 0; y < transformed_height; ++y) {
for (int x = 0; x < transformed_width; ++x) {
// Do transform.
double xy_matrix[3] = { x + x_min[i], y + y_min[i], 1 };
double uv_matrix[3] = { 0 };
multiply_mat(transform_matrix, xy_matrix, uv_matrix, TRANSFORM_MAT_DIM,
TRANSFORM_MAT_DIM, 1);
// Coordinates used for nearest neighbor interpolation.
int image_x = (int)round(uv_matrix[0]);
int image_y = (int)round(uv_matrix[1]);
// Temporary values for bilinear interpolation
double interpolated_yvalue = 0.0;
double interpolated_uvalue = 0.0;
double interpolated_vvalue = 0.0;
double interpolated_fraction = 0.0;
int interpolation_count = 0;
#if BGSPRITE_INTERPOLATION == 1
// Coordintes used for bilinear interpolation.
double x_base;
double y_base;
double x_decimal = modf(uv_matrix[0], &x_base);
double y_decimal = modf(uv_matrix[1], &y_base);
if ((x_decimal > 0.2 && x_decimal < 0.8) ||
(y_decimal > 0.2 && y_decimal < 0.8)) {
for (int u = 0; u < 2; ++u) {
for (int v = 0; v < 2; ++v) {
int interp_x = (int)x_base + u;
int interp_y = (int)y_base + v;
if (interp_x >= 0 && interp_x < frame_width && interp_y >= 0 &&
interp_y < frame_height) {
interpolation_count++;
interpolated_fraction +=
fabs(u - x_decimal) * fabs(v - y_decimal);
int ychannel_idx = interp_y * frames[i]->y_stride + interp_x;
int uvchannel_idx = (interp_y >> frames[i]->subsampling_y) *
frames[i]->uv_stride +
(interp_x >> frames[i]->subsampling_x);
#if CONFIG_HIGHBITDEPTH
if (frames[i]->flags & YV12_FLAG_HIGHBITDEPTH) {
interpolated_yvalue += (1 - fabs(u - x_decimal)) *
(1 - fabs(v - y_decimal)) *
y_buffer16[ychannel_idx];
interpolated_uvalue += (1 - fabs(u - x_decimal)) *
(1 - fabs(v - y_decimal)) *
u_buffer16[uvchannel_idx];
interpolated_vvalue += (1 - fabs(u - x_decimal)) *
(1 - fabs(v - y_decimal)) *
v_buffer16[uvchannel_idx];
} else {
#endif // CONFIG_HIGHBITDEPTH
interpolated_yvalue += (1 - fabs(u - x_decimal)) *
(1 - fabs(v - y_decimal)) *
frames[i]->y_buffer[ychannel_idx];
interpolated_uvalue += (1 - fabs(u - x_decimal)) *
(1 - fabs(v - y_decimal)) *
frames[i]->u_buffer[uvchannel_idx];
interpolated_vvalue += (1 - fabs(u - x_decimal)) *
(1 - fabs(v - y_decimal)) *
frames[i]->v_buffer[uvchannel_idx];
#if CONFIG_HIGHBITDEPTH
}
#endif // CONFIG_HIGHBITDEPTH
}
}
}
}
#endif // BGSPRITE_INTERPOLATION == 1
if (BGSPRITE_INTERPOLATION && interpolation_count > 2) {
if (interpolation_count != 4) {
interpolated_yvalue /= interpolated_fraction;
interpolated_uvalue /= interpolated_fraction;
interpolated_vvalue /= interpolated_fraction;
}
int pano_x = x + x_min[i] + x_offset;
int pano_y = y + y_min[i] + y_offset;
#if CONFIG_HIGHBITDEPTH
if (frames[i]->flags & YV12_FLAG_HIGHBITDEPTH) {
img_stack[pano_y][pano_x][i].y = (uint16_t)interpolated_yvalue;
img_stack[pano_y][pano_x][i].u = (uint16_t)interpolated_uvalue;
img_stack[pano_y][pano_x][i].v = (uint16_t)interpolated_vvalue;
img_stack[pano_y][pano_x][i].exists = 1;
} else {
#endif // CONFIG_HIGHBITDEPTH
img_stack[pano_y][pano_x][i].y = (uint8_t)interpolated_yvalue;
img_stack[pano_y][pano_x][i].u = (uint8_t)interpolated_uvalue;
img_stack[pano_y][pano_x][i].v = (uint8_t)interpolated_vvalue;
img_stack[pano_y][pano_x][i].exists = 1;
#if CONFIG_HIGHBITDEPTH
}
#endif // CONFIG_HIGHBITDEPTH
} else if (image_x >= 0 && image_x < frame_width && image_y >= 0 &&
image_y < frame_height) {
// Place in panorama stack.
int pano_x = x + x_min[i] + x_offset;
int pano_y = y + y_min[i] + y_offset;
int ychannel_idx = image_y * frames[i]->y_stride + image_x;
int uvchannel_idx =
(image_y >> frames[i]->subsampling_y) * frames[i]->uv_stride +
(image_x >> frames[i]->subsampling_x);
#if CONFIG_HIGHBITDEPTH
if (frames[i]->flags & YV12_FLAG_HIGHBITDEPTH) {
img_stack[pano_y][pano_x][i].y = y_buffer16[ychannel_idx];
img_stack[pano_y][pano_x][i].u = u_buffer16[uvchannel_idx];
img_stack[pano_y][pano_x][i].v = v_buffer16[uvchannel_idx];
img_stack[pano_y][pano_x][i].exists = 1;
} else {
#endif // CONFIG_HIGHBITDEPTH
img_stack[pano_y][pano_x][i].y = frames[i]->y_buffer[ychannel_idx];
img_stack[pano_y][pano_x][i].u = frames[i]->u_buffer[uvchannel_idx];
img_stack[pano_y][pano_x][i].v = frames[i]->v_buffer[uvchannel_idx];
img_stack[pano_y][pano_x][i].exists = 1;
#if CONFIG_HIGHBITDEPTH
}
#endif // CONFIG_HIGHBITDEPTH
}
}
}
}
}
#if BGSPRITE_BLENDING_MODE == 0
// swaps two YuvPixels.
static void swap_yuv(YuvPixel *a, YuvPixel *b) {
const YuvPixel temp = *b;
*b = *a;
*a = temp;
}
// Partitions array to find pivot index in qselect.
static int partition(YuvPixel arr[], int left, int right, int pivot_idx) {
YuvPixel pivot = arr[pivot_idx];
// Move pivot to the end.
swap_yuv(&arr[pivot_idx], &arr[right]);
int p_idx = left;
for (int i = left; i < right; ++i) {
if (arr[i].y <= pivot.y) {
swap_yuv(&arr[i], &arr[p_idx]);
p_idx++;
}
}
swap_yuv(&arr[p_idx], &arr[right]);
return p_idx;
}
// Returns the kth element in array, partially sorted in place (quickselect).
static YuvPixel qselect(YuvPixel arr[], int left, int right, int k) {
if (left >= right) {
return arr[left];
}
unsigned int seed = (int)time(NULL);
int pivot_idx = left + rand_r(&seed) % (right - left + 1);
pivot_idx = partition(arr, left, right, pivot_idx);
if (k == pivot_idx) {
return arr[k];
} else if (k < pivot_idx) {
return qselect(arr, left, pivot_idx - 1, k);
} else {
return qselect(arr, pivot_idx + 1, right, k);
}
}
// Blends image stack together using a temporal median.
static void blend_median(const int width, const int height,
const int num_frames, const YuvPixel ***image_stack,
YuvPixel **blended_img) {
// Allocate stack of pixels
YuvPixel *pixel_stack = aom_calloc(num_frames, sizeof(*pixel_stack));
// Apply median filtering using quickselect.
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
int count = 0;
for (int i = 0; i < num_frames; ++i) {
if (image_stack[y][x][i].exists) {
pixel_stack[count] = image_stack[y][x][i];
++count;
}
}
if (count == 0) {
// Just make the pixel black.
// TODO(toddnguyen): Color the pixel with nearest neighbor
blended_img[y][x].exists = 0;
} else {
const int median_idx = (int)floor(count / 2);
YuvPixel median = qselect(pixel_stack, 0, count - 1, median_idx);
// Make the median value the 0th index for UV subsampling later
blended_img[y][x] = median;
blended_img[y][x].exists = 1;
}
}
}
aom_free(pixel_stack);
}
#endif // BGSPRITE_BLENDING_MODE == 0
#if BGSPRITE_BLENDING_MODE == 1
// Blends image stack together using a temporal mean.
static void blend_mean(const int width, const int height, const int num_frames,
const YuvPixel ***image_stack, YuvPixel **blended_img,
int highbitdepth) {
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
// Find
uint32_t y_sum = 0;
uint32_t u_sum = 0;
uint32_t v_sum = 0;
uint32_t count = 0;
for (int i = 0; i < num_frames; ++i) {
if (image_stack[y][x][i].exists) {
y_sum += image_stack[y][x][i].y;
u_sum += image_stack[y][x][i].u;
v_sum += image_stack[y][x][i].v;
++count;
}
}
#if BGSPRITE_MEAN_REMOVE_OUTLIERS
if (count > 1) {
double stdev = 0;
double y_mean = (double)y_sum / count;
for (int i = 0; i < num_frames; ++i) {
if (image_stack[y][x][i].exists) {
stdev += pow(y_mean - image_stack[y][x][i].y, 2);
}
}
stdev = sqrt(stdev / count);
uint32_t inlier_y_sum = 0;
uint32_t inlier_u_sum = 0;
uint32_t inlier_v_sum = 0;
uint32_t inlier_count = 0;
for (int i = 0; i < num_frames; ++i) {
if (image_stack[y][x][i].exists &&
fabs(image_stack[y][x][i].y - y_mean) <= 1.5 * stdev) {
inlier_y_sum += image_stack[y][x][i].y;
inlier_u_sum += image_stack[y][x][i].u;
inlier_v_sum += image_stack[y][x][i].v;
++inlier_count;
}
}
count = inlier_count;
y_sum = inlier_y_sum;
u_sum = inlier_u_sum;
v_sum = inlier_v_sum;
}
#endif // BGSPRITE_MEAN_REMOVE_OUTLIERS
if (count != 0) {
blended_img[y][x].exists = 1;
#if CONFIG_HIGHBITDEPTH
if (highbitdepth) {
blended_img[y][x].y = (uint16_t)OD_DIVU(y_sum, count);
blended_img[y][x].u = (uint16_t)OD_DIVU(u_sum, count);
blended_img[y][x].v = (uint16_t)OD_DIVU(v_sum, count);
} else {
#endif // CONFIG_HIGHBITDEPTH
(void)highbitdepth;
blended_img[y][x].y = (uint8_t)OD_DIVU(y_sum, count);
blended_img[y][x].u = (uint8_t)OD_DIVU(u_sum, count);
blended_img[y][x].v = (uint8_t)OD_DIVU(v_sum, count);
#if CONFIG_HIGHBITDEPTH
}
#endif // CONFIG_HIGHBITDEPTH
} else {
blended_img[y][x].exists = 0;
}
}
}
}
#endif // BGSPRITE_BLENDING_MODE == 1
#if BGSPRITE_ENABLE_SEGMENTATION
// Builds dual-mode single gaussian model from image stack.
static void build_gaussian(const YuvPixel ***image_stack, const int num_frames,
const int width, const int height,
const int x_block_width, const int y_block_height,
const int block_size, YuvPixelGaussian **gauss) {
const double initial_variance = 10.0;
const double s_theta = 2.0;
// Add images to dual-mode single gaussian model
for (int y_block = 0; y_block < y_block_height; ++y_block) {
for (int x_block = 0; x_block < x_block_width; ++x_block) {
// Process all blocks.
YuvPixelGaussian *model = &gauss[y_block][x_block];
// Process all frames.
for (int i = 0; i < num_frames; ++i) {
// Add block to the Gaussian model.
double max_variance[2] = { 0.0, 0.0 };
double temp_y_mean = 0.0;
double temp_u_mean = 0.0;
double temp_v_mean = 0.0;
// Find mean/variance of a block of pixels.
int temp_count = 0;
for (int sub_y = 0; sub_y < block_size; ++sub_y) {
for (int sub_x = 0; sub_x < block_size; ++sub_x) {
const int y = y_block * block_size + sub_y;
const int x = x_block * block_size + sub_x;
if (y < height && x < width && image_stack[y][x][i].exists) {
++temp_count;
temp_y_mean += (double)image_stack[y][x][i].y;
temp_u_mean += (double)image_stack[y][x][i].u;
temp_v_mean += (double)image_stack[y][x][i].v;
const double variance_0 =
pow((double)image_stack[y][x][i].y - model->mean[0], 2);
const double variance_1 =
pow((double)image_stack[y][x][i].y - model->mean[1], 2);
if (variance_0 > max_variance[0]) {
max_variance[0] = variance_0;
}
if (variance_1 > max_variance[1]) {
max_variance[1] = variance_1;
}
}
}
}
// If pixels exist in the block, add to the model.
if (temp_count > 0) {
assert(temp_count <= block_size * block_size);
temp_y_mean /= temp_count;
temp_u_mean /= temp_count;
temp_v_mean /= temp_count;
// Switch the background model to the oldest model.
if (model->age[0] > model->age[1]) {
model->curr_model = 0;
} else if (model->age[1] > model->age[0]) {
model->curr_model = 1;
}
// If model is empty, initialize model.
if (model->age[model->curr_model] == 0) {
model->mean[model->curr_model] = temp_y_mean;
model->u_mean[model->curr_model] = temp_u_mean;
model->v_mean[model->curr_model] = temp_v_mean;
model->var[model->curr_model] = initial_variance;
model->age[model->curr_model] = 1;
} else {
// Constants for current model and foreground model (0 or 1).
const int opposite = 1 - model->curr_model;
const int current = model->curr_model;
const double j = i;
// Put block into the appropriate model.
if (pow(temp_y_mean - model->mean[current], 2) <
s_theta * model->var[current]) {
// Add block to the current background model
model->age[current] += 1;
const double prev_weight = 1 / j;
const double curr_weight = (j - 1) / j;
model->mean[current] = prev_weight * model->mean[current] +
curr_weight * temp_y_mean;
model->u_mean[current] = prev_weight * model->u_mean[current] +
curr_weight * temp_u_mean;
model->v_mean[current] = prev_weight * model->v_mean[current] +
curr_weight * temp_v_mean;
model->var[current] = prev_weight * model->var[current] +
curr_weight * max_variance[current];
} else {
// Block does not fit into current background candidate. Add to
// foreground candidate and reinitialize if necessary.
const double var_fg = pow(temp_y_mean - model->mean[opposite], 2);
if (var_fg <= s_theta * model->var[opposite]) {
model->age[opposite] += 1;
const double prev_weight = 1 / j;
const double curr_weight = (j - 1) / j;
model->mean[opposite] = prev_weight * model->mean[opposite] +
curr_weight * temp_y_mean;
model->u_mean[opposite] =
prev_weight * model->u_mean[opposite] +
curr_weight * temp_u_mean;
model->v_mean[opposite] =
prev_weight * model->v_mean[opposite] +
curr_weight * temp_v_mean;
model->var[opposite] = prev_weight * model->var[opposite] +
curr_weight * max_variance[opposite];
} else if (model->age[opposite] == 0 ||
var_fg > s_theta * model->var[opposite]) {
model->mean[opposite] = temp_y_mean;
model->u_mean[opposite] = temp_u_mean;
model->v_mean[opposite] = temp_v_mean;
model->var[opposite] = initial_variance;
model->age[opposite] = 1;
} else {
// This case should never happen.
assert(0);
}
}
}
}
}
// Select the oldest candidate as the background model.
if (model->age[0] == 0 && model->age[1] == 0) {
model->y = 0;
model->u = 0;
model->v = 0;
model->final_var = 0;
} else if (model->age[0] > model->age[1]) {
model->y = (uint8_t)model->mean[0];
model->u = (uint8_t)model->u_mean[0];
model->v = (uint8_t)model->v_mean[0];
model->final_var = model->var[0];
} else {
model->y = (uint8_t)model->mean[1];
model->u = (uint8_t)model->u_mean[1];
model->v = (uint8_t)model->v_mean[1];
model->final_var = model->var[1];
}
}
}
}
// Builds foreground mask based on reference image and gaussian model.
// In mask[][], 1 is foreground and 0 is background.
static void build_mask(const int x_min, const int y_min, const int x_offset,
const int y_offset, const int x_block_width,
const int y_block_height, const int block_size,
const YuvPixelGaussian **gauss,
YV12_BUFFER_CONFIG *const reference,
YV12_BUFFER_CONFIG *const panorama, uint8_t **mask) {
const int crop_x_offset = x_min + x_offset;
const int crop_y_offset = y_min + y_offset;
const double d_theta = 4.0;
for (int y_block = 0; y_block < y_block_height; ++y_block) {
for (int x_block = 0; x_block < x_block_width; ++x_block) {
// Create mask to determine if ARF is background for foreground.
const YuvPixelGaussian *model = &gauss[y_block][x_block];
double temp_y_mean = 0.0;
int temp_count = 0;
for (int sub_y = 0; sub_y < block_size; ++sub_y) {
for (int sub_x = 0; sub_x < block_size; ++sub_x) {
// x and y are panorama coordinates.
const int y = y_block * block_size + sub_y;
const int x = x_block * block_size + sub_x;
const int arf_y = y - crop_y_offset;
const int arf_x = x - crop_x_offset;
if (arf_y >= 0 && arf_y < panorama->y_height && arf_x >= 0 &&
arf_x < panorama->y_width) {
++temp_count;
const int ychannel_idx = arf_y * panorama->y_stride + arf_x;
temp_y_mean += (double)reference->y_buffer[ychannel_idx];
}
}
}
if (temp_count > 0) {
assert(temp_count <= block_size * block_size);
temp_y_mean /= temp_count;
if (pow(temp_y_mean - model->y, 2) > model->final_var * d_theta) {
// Mark block as foreground.
mask[y_block][x_block] = 1;
}
}
}
}
}
#endif // BGSPRITE_ENABLE_SEGMENTATION
// Resamples blended_img into panorama, including UV subsampling.
static void resample_panorama(YuvPixel **blended_img, const int center_idx,
const int *const x_min, const int *const y_min,
int pano_x_min, int pano_x_max, int pano_y_min,
int pano_y_max, YV12_BUFFER_CONFIG *panorama) {
const int width = pano_x_max - pano_x_min + 1;
const int height = pano_y_max - pano_y_min + 1;
const int x_offset = -pano_x_min;
const int y_offset = -pano_y_min;
const int crop_x_offset = x_min[center_idx] + x_offset;
const int crop_y_offset = y_min[center_idx] + y_offset;
#if CONFIG_HIGHBITDEPTH
if (panorama->flags & YV12_FLAG_HIGHBITDEPTH) {
// Use median Y value.
uint16_t *pano_y_buffer16 = CONVERT_TO_SHORTPTR(panorama->y_buffer);
uint16_t *pano_u_buffer16 = CONVERT_TO_SHORTPTR(panorama->u_buffer);
uint16_t *pano_v_buffer16 = CONVERT_TO_SHORTPTR(panorama->v_buffer);
for (int y = 0; y < panorama->y_height; ++y) {
for (int x = 0; x < panorama->y_width; ++x) {
const int ychannel_idx = y * panorama->y_stride + x;
if (blended_img[y + crop_y_offset][x + crop_x_offset].exists) {
pano_y_buffer16[ychannel_idx] =
blended_img[y + crop_y_offset][x + crop_x_offset].y;
} else {
pano_y_buffer16[ychannel_idx] = 0;
}
}
}
// UV subsampling with median UV values
for (int y = 0; y < panorama->uv_height; ++y) {
for (int x = 0; x < panorama->uv_width; ++x) {
uint32_t avg_count = 0;
uint32_t u_sum = 0;
uint32_t v_sum = 0;
// Look at surrounding pixels for subsampling
for (int s_x = 0; s_x < panorama->subsampling_x + 1; ++s_x) {
for (int s_y = 0; s_y < panorama->subsampling_y + 1; ++s_y) {
int y_sample = crop_y_offset + (y << panorama->subsampling_y) + s_y;
int x_sample = crop_x_offset + (x << panorama->subsampling_x) + s_x;
if (y_sample > 0 && y_sample < height && x_sample > 0 &&
x_sample < width && blended_img[y_sample][x_sample].exists) {
u_sum += blended_img[y_sample][x_sample].u;
v_sum += blended_img[y_sample][x_sample].v;
avg_count++;
}
}
}
const int uvchannel_idx = y * panorama->uv_stride + x;
if (avg_count != 0) {
pano_u_buffer16[uvchannel_idx] = (uint16_t)OD_DIVU(u_sum, avg_count);
pano_v_buffer16[uvchannel_idx] = (uint16_t)OD_DIVU(v_sum, avg_count);
} else {
pano_u_buffer16[uvchannel_idx] = 0;
pano_v_buffer16[uvchannel_idx] = 0;
}
}
}
} else {
#endif // CONFIG_HIGHBITDEPTH
// Use blended Y value.
for (int y = 0; y < panorama->y_height; ++y) {
for (int x = 0; x < panorama->y_width; ++x) {
const int ychannel_idx = y * panorama->y_stride + x;
// Use filtered background.
if (blended_img[y + crop_y_offset][x + crop_x_offset].exists) {
panorama->y_buffer[ychannel_idx] =
blended_img[y + crop_y_offset][x + crop_x_offset].y;
} else {
panorama->y_buffer[ychannel_idx] = 0;
}
}
}
// UV subsampling with blended UV values.
for (int y = 0; y < panorama->uv_height; ++y) {
for (int x = 0; x < panorama->uv_width; ++x) {
uint16_t avg_count = 0;
uint16_t u_sum = 0;
uint16_t v_sum = 0;
// Look at surrounding pixels for subsampling.
for (int s_x = 0; s_x < panorama->subsampling_x + 1; ++s_x) {
for (int s_y = 0; s_y < panorama->subsampling_y + 1; ++s_y) {
int y_sample = crop_y_offset + (y << panorama->subsampling_y) + s_y;
int x_sample = crop_x_offset + (x << panorama->subsampling_x) + s_x;
if (y_sample > 0 && y_sample < height && x_sample > 0 &&
x_sample < width && blended_img[y_sample][x_sample].exists) {
u_sum += blended_img[y_sample][x_sample].u;
v_sum += blended_img[y_sample][x_sample].v;
avg_count++;
}
}
}
const int uvchannel_idx = y * panorama->uv_stride + x;
if (avg_count != 0) {
panorama->u_buffer[uvchannel_idx] =
(uint8_t)OD_DIVU(u_sum, avg_count);
panorama->v_buffer[uvchannel_idx] =
(uint8_t)OD_DIVU(v_sum, avg_count);
} else {
panorama->u_buffer[uvchannel_idx] = 0;
panorama->v_buffer[uvchannel_idx] = 0;
}
}
}
#if CONFIG_HIGHBITDEPTH
}
#endif // CONFIG_HIGHBITDEPTH
}
#if BGSPRITE_ENABLE_SEGMENTATION
// Combines temporal filter output and bgsprite output to make final ARF output
static void combine_arf(YV12_BUFFER_CONFIG *const temporal_arf,
YV12_BUFFER_CONFIG *const bgsprite,
uint8_t **const mask, const int block_size,
const int x_offset, const int y_offset,
YV12_BUFFER_CONFIG *target) {
const int height = temporal_arf->y_height;
const int width = temporal_arf->y_width;
YuvPixel **blended_img = aom_malloc(height * sizeof(*blended_img));
for (int i = 0; i < height; ++i) {
blended_img[i] = aom_malloc(width * sizeof(**blended_img));
}
const int block_2_height = (height / BGSPRITE_MASK_BLOCK_SIZE) +
(height % BGSPRITE_MASK_BLOCK_SIZE != 0 ? 1 : 0);
const int block_2_width = (width / BGSPRITE_MASK_BLOCK_SIZE) +
(width % BGSPRITE_MASK_BLOCK_SIZE != 0 ? 1 : 0);
for (int block_y = 0; block_y < block_2_height; ++block_y) {
for (int block_x = 0; block_x < block_2_width; ++block_x) {
int count = 0;
int total = 0;
for (int sub_y = 0; sub_y < BGSPRITE_MASK_BLOCK_SIZE; ++sub_y) {
for (int sub_x = 0; sub_x < BGSPRITE_MASK_BLOCK_SIZE; ++sub_x) {
const int img_y = block_y * BGSPRITE_MASK_BLOCK_SIZE + sub_y;
const int img_x = block_x * BGSPRITE_MASK_BLOCK_SIZE + sub_x;
const int mask_y = (y_offset + img_y) / block_size;
const int mask_x = (x_offset + img_x) / block_size;
if (img_y < height && img_x < width) {
if (mask[mask_y][mask_x]) {
++count;
}
++total;
}
}
}
const double threshold = 0.30;
const int amount = (int)(threshold * total);
for (int sub_y = 0; sub_y < BGSPRITE_MASK_BLOCK_SIZE; ++sub_y) {
for (int sub_x = 0; sub_x < BGSPRITE_MASK_BLOCK_SIZE; ++sub_x) {
const int y = block_y * BGSPRITE_MASK_BLOCK_SIZE + sub_y;
const int x = block_x * BGSPRITE_MASK_BLOCK_SIZE + sub_x;
if (y < height && x < width) {
blended_img[y][x].exists = 1;
const int ychannel_idx = y * temporal_arf->y_stride + x;
const int uvchannel_idx =
(y >> temporal_arf->subsampling_y) * temporal_arf->uv_stride +
(x >> temporal_arf->subsampling_x);
if (count > amount) {
// Foreground; use temporal arf.
#if CONFIG_HIGHBITDEPTH
if (temporal_arf->flags & YV12_FLAG_HIGHBITDEPTH) {
uint16_t *pano_y_buffer16 =
CONVERT_TO_SHORTPTR(temporal_arf->y_buffer);
uint16_t *pano_u_buffer16 =
CONVERT_TO_SHORTPTR(temporal_arf->u_buffer);
uint16_t *pano_v_buffer16 =
CONVERT_TO_SHORTPTR(temporal_arf->v_buffer);
blended_img[y][x].y = pano_y_buffer16[ychannel_idx];
blended_img[y][x].u = pano_u_buffer16[uvchannel_idx];
blended_img[y][x].v = pano_v_buffer16[uvchannel_idx];
} else {
#endif // CONFIG_HIGHBITDEPTH
blended_img[y][x].y = temporal_arf->y_buffer[ychannel_idx];
blended_img[y][x].u = temporal_arf->u_buffer[uvchannel_idx];
blended_img[y][x].v = temporal_arf->v_buffer[uvchannel_idx];
#if CONFIG_HIGHBITDEPTH
}
#endif // CONFIG_HIGHBITDEPTH
} else {
// Background; use bgsprite arf.
#if CONFIG_HIGHBITDEPTH
if (bgsprite->flags & YV12_FLAG_HIGHBITDEPTH) {
uint16_t *pano_y_buffer16 =
CONVERT_TO_SHORTPTR(bgsprite->y_buffer);
uint16_t *pano_u_buffer16 =
CONVERT_TO_SHORTPTR(bgsprite->u_buffer);
uint16_t *pano_v_buffer16 =
CONVERT_TO_SHORTPTR(bgsprite->v_buffer);
blended_img[y][x].y = pano_y_buffer16[ychannel_idx];
blended_img[y][x].u = pano_u_buffer16[uvchannel_idx];
blended_img[y][x].v = pano_v_buffer16[uvchannel_idx];
} else {
#endif // CONFIG_HIGHBITDEPTH
blended_img[y][x].y = bgsprite->y_buffer[ychannel_idx];
blended_img[y][x].u = bgsprite->u_buffer[uvchannel_idx];
blended_img[y][x].v = bgsprite->v_buffer[uvchannel_idx];
#if CONFIG_HIGHBITDEPTH
}
#endif // CONFIG_HIGHBITDEPTH
}
}
}
}
}
}
const int x_min = 0;
const int y_min = 0;
resample_panorama(blended_img, 0, &x_min, &y_min, 0, width - 1, 0, height - 1,
target);
for (int i = 0; i < height; ++i) {
aom_free(blended_img[i]);
}
aom_free(blended_img);
}
#endif // BGSPRITE_ENABLE_SEGMENTATION
// Stitches images together to create ARF and stores it in 'panorama'.
static void stitch_images(AV1_COMP *cpi, YV12_BUFFER_CONFIG **const frames,
const int num_frames, const int distance,
const int center_idx, const double **const params,
const int *const x_min, const int *const x_max,
const int *const y_min, const int *const y_max,
int pano_x_min, int pano_x_max, int pano_y_min,
int pano_y_max, YV12_BUFFER_CONFIG *panorama) {
const int width = pano_x_max - pano_x_min + 1;
const int height = pano_y_max - pano_y_min + 1;
// Create pano_stack[y][x][num_frames] stack of pixel values
YuvPixel ***pano_stack = aom_malloc(height * sizeof(*pano_stack));
for (int i = 0; i < height; ++i) {
pano_stack[i] = aom_malloc(width * sizeof(**pano_stack));
for (int j = 0; j < width; ++j) {
pano_stack[i][j] = aom_calloc(num_frames, sizeof(***pano_stack));
}
}
build_image_stack(frames, num_frames, params, x_min, x_max, y_min, y_max,
pano_x_min, pano_y_min, pano_stack);
// Create blended_img[y][x] of combined panorama pixel values.
YuvPixel **blended_img = aom_malloc(height * sizeof(*blended_img));
for (int i = 0; i < height; ++i) {
blended_img[i] = aom_malloc(width * sizeof(**blended_img));
}
// Blending and saving result in blended_img.
#if BGSPRITE_BLENDING_MODE == 1
blend_mean(width, height, num_frames, (const YuvPixel ***)pano_stack,
blended_img, panorama->flags & YV12_FLAG_HIGHBITDEPTH);
#else // BGSPRITE_BLENDING_MODE != 1
blend_median(width, height, num_frames, (const YuvPixel ***)pano_stack,
blended_img);
#endif // BGSPRITE_BLENDING_MODE == 1
// NOTE(toddnguyen): Right now the ARF in the cpi struct is fixed size at
// the same size as the frames. For now, we crop the generated panorama.
assert(panorama->y_width <= width && panorama->y_height <= height);
// Resamples the blended_img into the panorama buffer.
YV12_BUFFER_CONFIG bgsprite;
memset(&bgsprite, 0, sizeof(bgsprite));
aom_alloc_frame_buffer(&bgsprite, frames[0]->y_width, frames[0]->y_height,
frames[0]->subsampling_x, frames[0]->subsampling_y,
#if CONFIG_HIGHBITDEPTH
frames[0]->flags & YV12_FLAG_HIGHBITDEPTH,
#endif
frames[0]->border, 0);
aom_yv12_copy_frame(frames[0], &bgsprite);
bgsprite.bit_depth = frames[0]->bit_depth;
resample_panorama(blended_img, center_idx, x_min, y_min, pano_x_min,
pano_x_max, pano_y_min, pano_y_max, &bgsprite);
#if BGSPRITE_ENABLE_SEGMENTATION
YV12_BUFFER_CONFIG temporal_bgsprite;
memset(&temporal_bgsprite, 0, sizeof(temporal_bgsprite));
aom_alloc_frame_buffer(&temporal_bgsprite, frames[0]->y_width,
frames[0]->y_height, frames[0]->subsampling_x,
frames[0]->subsampling_y,
#if CONFIG_HIGHBITDEPTH
frames[0]->flags & YV12_FLAG_HIGHBITDEPTH,
#endif
frames[0]->border, 0);
aom_yv12_copy_frame(frames[0], &temporal_bgsprite);
temporal_bgsprite.bit_depth = frames[0]->bit_depth;
av1_temporal_filter(cpi, &bgsprite, &temporal_bgsprite, distance);
// Block size constants for gaussian model.
const int N_1 = 2;
const int y_block_height = (height / N_1) + (height % N_1 != 0 ? 1 : 0);
const int x_block_width = (width / N_1) + (height % N_1 != 0 ? 1 : 0);
YuvPixelGaussian **gauss = aom_malloc(y_block_height * sizeof(*gauss));
for (int i = 0; i < y_block_height; ++i) {
gauss[i] = aom_calloc(x_block_width, sizeof(**gauss));
}
// Build Gaussian model.
build_gaussian((const YuvPixel ***)pano_stack, num_frames, width, height,
x_block_width, y_block_height, N_1, gauss);
// Select background model and build foreground mask.
uint8_t **mask = aom_malloc(y_block_height * sizeof(*mask));
for (int i = 0; i < y_block_height; ++i) {
mask[i] = aom_calloc(x_block_width, sizeof(**mask));
}
const int x_offset = -pano_x_min;
const int y_offset = -pano_y_min;
build_mask(x_min[center_idx], y_min[center_idx], x_offset, y_offset,
x_block_width, y_block_height, N_1,
(const YuvPixelGaussian **)gauss,
(YV12_BUFFER_CONFIG * const)frames[center_idx], panorama, mask);
YV12_BUFFER_CONFIG temporal_arf;
memset(&temporal_arf, 0, sizeof(temporal_arf));
aom_alloc_frame_buffer(&temporal_arf, frames[0]->y_width, frames[0]->y_height,
frames[0]->subsampling_x, frames[0]->subsampling_y,
#if CONFIG_HIGHBITDEPTH
frames[0]->flags & YV12_FLAG_HIGHBITDEPTH,
#endif
frames[0]->border, 0);
aom_yv12_copy_frame(frames[0], &temporal_arf);
temporal_arf.bit_depth = frames[0]->bit_depth;
av1_temporal_filter(cpi, NULL, &temporal_arf, distance);
combine_arf(&temporal_arf, &temporal_bgsprite, mask, N_1, x_offset, y_offset,
panorama);
aom_free_frame_buffer(&temporal_arf);
aom_free_frame_buffer(&temporal_bgsprite);
for (int i = 0; i < y_block_height; ++i) {
aom_free(gauss[i]);
aom_free(mask[i]);
}
aom_free(gauss);
aom_free(mask);
#else // !BGSPRITE_ENABLE_SEGMENTATION
av1_temporal_filter(cpi, &bgsprite, panorama, distance);
#endif // BGSPRITE_ENABLE_SEGMENTATION
aom_free_frame_buffer(&bgsprite);
for (int i = 0; i < height; ++i) {
for (int j = 0; j < width; ++j) {
aom_free(pano_stack[i][j]);
}
aom_free(pano_stack[i]);
aom_free(blended_img[i]);
}
aom_free(pano_stack);
aom_free(blended_img);
}
int av1_background_sprite(AV1_COMP *cpi, int distance) {
#if BGSPRITE_ENABLE_METRICS
// Do temporal filter if firstpass stats disable bgsprite.
if (!cpi->bgsprite_allowed) {
return 1;
}
#endif // BGSPRITE_ENABLE_METRICS
YV12_BUFFER_CONFIG *frames[MAX_LAG_BUFFERS] = { NULL };
static const double identity_params[MAX_PARAMDIM - 1] = {
0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0
};
const int frames_after_arf =
av1_lookahead_depth(cpi->lookahead) - distance - 1;
int frames_fwd = (cpi->oxcf.arnr_max_frames - 1) >> 1;
int frames_bwd;
// Define the forward and backwards filter limits for this arnr group.
if (frames_fwd > frames_after_arf) frames_fwd = frames_after_arf;
if (frames_fwd > distance) frames_fwd = distance;
frames_bwd = frames_fwd;
#if CONFIG_EXT_REFS
const GF_GROUP *const gf_group = &cpi->twopass.gf_group;
if (gf_group->rf_level[gf_group->index] == GF_ARF_LOW) {
cpi->is_arf_filter_off[gf_group->arf_update_idx[gf_group->index]] = 1;
frames_fwd = 0;
frames_bwd = 0;
} else {
cpi->is_arf_filter_off[gf_group->arf_update_idx[gf_group->index]] = 0;
}
#endif // CONFIG_EXT_REFS
const int start_frame = distance + frames_fwd;
const int frames_to_stitch = frames_bwd + 1 + frames_fwd;
// Get frames to be included in background sprite.
for (int frame = 0; frame < frames_to_stitch; ++frame) {
const int which_buffer = start_frame - frame;
struct lookahead_entry *buf =
av1_lookahead_peek(cpi->lookahead, which_buffer);
frames[frames_to_stitch - 1 - frame] = &buf->img;
}
// Allocate empty arrays for parameters between frames.
double **params = aom_malloc(frames_to_stitch * sizeof(*params));
for (int i = 0; i < frames_to_stitch; ++i) {
params[i] = aom_malloc(sizeof(identity_params));
memcpy(params[i], identity_params, sizeof(identity_params));
}
// Use global motion to find affine transformations between frames.
// params[i] will have the transform from frame[i] to frame[i-1].
// params[0] will have the identity matrix (has no previous frame).
#if BGSPRITE_ENABLE_GME
TransformationType model = AFFINE;
int inliers_by_motion[RANSAC_NUM_MOTIONS];
for (int frame = 0; frame < frames_to_stitch - 1; ++frame) {
const int global_motion_ret = compute_global_motion_feature_based(
model, frames[frame + 1], frames[frame],
#if CONFIG_HIGHBITDEPTH
cpi->common.bit_depth,
#endif // CONFIG_HIGHBITDEPTH
inliers_by_motion, params[frame + 1], RANSAC_NUM_MOTIONS);
// Quit if global motion had an error.
if (global_motion_ret == 0) {
for (int i = 0; i < frames_to_stitch; ++i) {
aom_free(params[i]);
}
aom_free(params);
return 1;
}
}
#endif // BGSPRITE_ENABLE_GME
// Compound the transformation parameters.
for (int i = 1; i < frames_to_stitch; ++i) {
multiply_params(params[i - 1], params[i], params[i]);
}
// Compute frame limits for final stitched images.
int pano_x_max = INT_MIN;
int pano_x_min = INT_MAX;
int pano_y_max = INT_MIN;
int pano_y_min = INT_MAX;
int *x_max = aom_malloc(frames_to_stitch * sizeof(*x_max));
int *x_min = aom_malloc(frames_to_stitch * sizeof(*x_min));
int *y_max = aom_malloc(frames_to_stitch * sizeof(*y_max));
int *y_min = aom_malloc(frames_to_stitch * sizeof(*y_min));
find_limits(frames[0]->y_width, frames[0]->y_height,
(const double **const)params, frames_to_stitch, x_min, x_max,
y_min, y_max, &pano_x_min, &pano_x_max, &pano_y_min, &pano_y_max);
// Center panorama on the ARF.
const int center_idx = frames_bwd;
assert(center_idx >= 0 && center_idx < frames_to_stitch);
// Recompute transformations to adjust to center image.
// Invert center image's transform.
double inverse[MAX_PARAMDIM - 1] = { 0 };
invert_params(params[center_idx], inverse);
// Multiply the inverse to all transformation parameters.
for (int i = 0; i < frames_to_stitch; ++i) {
multiply_params(inverse, params[i], params[i]);
}
// Recompute frame limits for new adjusted center.
find_limits(frames[0]->y_width, frames[0]->y_height,
(const double **const)params, frames_to_stitch, x_min, x_max,
y_min, y_max, &pano_x_min, &pano_x_max, &pano_y_min, &pano_y_max);
// Stitch Images and apply bgsprite filter.
stitch_images(cpi, frames, frames_to_stitch, distance, center_idx,
(const double **const)params, x_min, x_max, y_min, y_max,
pano_x_min, pano_x_max, pano_y_min, pano_y_max,
&cpi->alt_ref_buffer);
// Free memory.
for (int i = 0; i < frames_to_stitch; ++i) {
aom_free(params[i]);
}
aom_free(params);
aom_free(x_max);
aom_free(x_min);
aom_free(y_max);
aom_free(y_min);
return 0;
}
#undef _POSIX_C_SOURCE
#undef BGSPRITE_BLENDING_MODE
#undef BGSPRITE_INTERPOLATION
#undef BGSPRITE_ENABLE_METRICS
#undef BGSPRITE_ENABLE_SEGMENTATION
#undef BGSPRITE_ENABLE_GME
#undef BGSPRITE_MASK_BLOCK_SIZE
#undef TRANSFORM_MAT_DIM