1 files changed, 39 insertions, 17 deletions

diff --git a/third_party/aom/av1/common/scale.c b/third_party/aom/av1/common/scale.c
index 76beaa2bd..d5ccdfec0 100644
--- a/third_party/aom/av1/common/scale.c
+++ b/third_party/aom/av1/common/scale.c
@@ -14,17 +14,28 @@
 #include "av1/common/scale.h"
 #include "aom_dsp/aom_filter.h"
 
+// Note: Expect val to be in q4 precision
 static INLINE int scaled_x(int val, const struct scale_factors *sf) {
-  return (int)((int64_t)val * sf->x_scale_fp >> REF_SCALE_SHIFT);
+  const int off =
+      (sf->x_scale_fp - (1 << REF_SCALE_SHIFT)) * (1 << (SUBPEL_BITS - 1));
+  const int64_t tval = (int64_t)val * sf->x_scale_fp + off;
+  return (int)ROUND_POWER_OF_TWO_SIGNED_64(tval,
+                                           REF_SCALE_SHIFT - SCALE_EXTRA_BITS);
 }
 
+// Note: Expect val to be in q4 precision
 static INLINE int scaled_y(int val, const struct scale_factors *sf) {
-  return (int)((int64_t)val * sf->y_scale_fp >> REF_SCALE_SHIFT);
+  const int off =
+      (sf->y_scale_fp - (1 << REF_SCALE_SHIFT)) * (1 << (SUBPEL_BITS - 1));
+  const int64_t tval = (int64_t)val * sf->y_scale_fp + off;
+  return (int)ROUND_POWER_OF_TWO_SIGNED_64(tval,
+                                           REF_SCALE_SHIFT - SCALE_EXTRA_BITS);
 }
 
+// Note: Expect val to be in q4 precision
 static int unscaled_value(int val, const struct scale_factors *sf) {
   (void)sf;
-  return val;
+  return val << SCALE_EXTRA_BITS;
 }
 
 static int get_fixed_point_scale_factor(int other_size, int this_size) {
@@ -32,14 +43,24 @@ static int get_fixed_point_scale_factor(int other_size, int this_size) {
   // and use fixed point scaling factors in decoding and encoding routines.
   // Hardware implementations can calculate scale factor in device driver
   // and use multiplication and shifting on hardware instead of division.
-  return (other_size << REF_SCALE_SHIFT) / this_size;
+  return ((other_size << REF_SCALE_SHIFT) + this_size / 2) / this_size;
 }
 
-MV32 av1_scale_mv(const MV *mv, int x, int y, const struct scale_factors *sf) {
-  const int x_off_q4 = scaled_x(x << SUBPEL_BITS, sf) & SUBPEL_MASK;
-  const int y_off_q4 = scaled_y(y << SUBPEL_BITS, sf) & SUBPEL_MASK;
-  const MV32 res = { scaled_y(mv->row, sf) + y_off_q4,
-                     scaled_x(mv->col, sf) + x_off_q4 };
+static int get_coarse_point_scale_factor(int other_size, int this_size) {
+  // Calculate scaling factor once for each reference frame
+  // and use fixed point scaling factors in decoding and encoding routines.
+  // Hardware implementations can calculate scale factor in device driver
+  // and use multiplication and shifting on hardware instead of division.
+  return ((other_size << SCALE_SUBPEL_BITS) + this_size / 2) / this_size;
+}
+
+// Note: x and y are integer precision, mvq4 is q4 precision.
+MV32 av1_scale_mv(const MV *mvq4, int x, int y,
+                  const struct scale_factors *sf) {
+  const int x_off_q4 = scaled_x(x << SUBPEL_BITS, sf);
+  const int y_off_q4 = scaled_y(y << SUBPEL_BITS, sf);
+  const MV32 res = { scaled_y((y << SUBPEL_BITS) + mvq4->row, sf) - y_off_q4,
+                     scaled_x((x << SUBPEL_BITS) + mvq4->col, sf) - x_off_q4 };
   return res;
 }
 
@@ -59,8 +80,9 @@ void av1_setup_scale_factors_for_frame(struct scale_factors *sf, int other_w,
 
   sf->x_scale_fp = get_fixed_point_scale_factor(other_w, this_w);
   sf->y_scale_fp = get_fixed_point_scale_factor(other_h, this_h);
-  sf->x_step_q4 = scaled_x(16, sf);
-  sf->y_step_q4 = scaled_y(16, sf);
+
+  sf->x_step_q4 = get_coarse_point_scale_factor(other_w, this_w);
+  sf->y_step_q4 = get_coarse_point_scale_factor(other_h, this_h);
 
   if (av1_is_scaled(sf)) {
     sf->scale_value_x = scaled_x;
@@ -76,8 +98,8 @@ void av1_setup_scale_factors_for_frame(struct scale_factors *sf, int other_w,
   // applied in one direction only, and not at all for 0,0, seems to give the
   // best quality, but it may be worth trying an additional mode that does
   // do the filtering on full-pel.
-  if (sf->x_step_q4 == 16) {
-    if (sf->y_step_q4 == 16) {
+  if (sf->x_step_q4 == SCALE_SUBPEL_SHIFTS) {
+    if (sf->y_step_q4 == SCALE_SUBPEL_SHIFTS) {
       // No scaling in either direction.
       sf->predict[0][0][0] = aom_convolve_copy;
       sf->predict[0][0][1] = aom_convolve_avg;
@@ -95,7 +117,7 @@ void av1_setup_scale_factors_for_frame(struct scale_factors *sf, int other_w,
       sf->predict[1][0][1] = aom_convolve8_avg;
     }
   } else {
-    if (sf->y_step_q4 == 16) {
+    if (sf->y_step_q4 == SCALE_SUBPEL_SHIFTS) {
       // No scaling in the y direction. Must always scale in the x direction.
       sf->predict[0][0][0] = aom_convolve8_horiz;
       sf->predict[0][0][1] = aom_convolve8_avg_horiz;
@@ -119,8 +141,8 @@ void av1_setup_scale_factors_for_frame(struct scale_factors *sf, int other_w,
 
 #if CONFIG_HIGHBITDEPTH
   if (use_highbd) {
-    if (sf->x_step_q4 == 16) {
-      if (sf->y_step_q4 == 16) {
+    if (sf->x_step_q4 == SCALE_SUBPEL_SHIFTS) {
+      if (sf->y_step_q4 == SCALE_SUBPEL_SHIFTS) {
         // No scaling in either direction.
         sf->highbd_predict[0][0][0] = aom_highbd_convolve_copy;
         sf->highbd_predict[0][0][1] = aom_highbd_convolve_avg;
@@ -138,7 +160,7 @@ void av1_setup_scale_factors_for_frame(struct scale_factors *sf, int other_w,
         sf->highbd_predict[1][0][1] = aom_highbd_convolve8_avg;
       }
     } else {
-      if (sf->y_step_q4 == 16) {
+      if (sf->y_step_q4 == SCALE_SUBPEL_SHIFTS) {
         // No scaling in the y direction. Must always scale in the x direction.
         sf->highbd_predict[0][0][0] = aom_highbd_convolve8_horiz;
         sf->highbd_predict[0][0][1] = aom_highbd_convolve8_avg_horiz;