Update aom to v1.0.0

Update aom to commit id d14c5bb4f336ef1842046089849dee4a301fbbf0.

1 files changed, 0 insertions, 1257 deletions

diff --git a/third_party/aom/av1/encoder/bgsprite.c b/third_party/aom/av1/encoder/bgsprite.c
deleted file mode 100644
index ae2cb1d40..000000000
--- a/third_party/aom/av1/encoder/bgsprite.c
+++ /dev/null
@@ -1,1257 +0,0 @@
-/*
- * 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