Import aom library

This is the reference implementation for the Alliance for Open Media's av1 video code.

The commit used was 4d668d7feb1f8abd809d1bca0418570a7f142a36.

1 files changed, 1164 insertions, 0 deletions

diff --git a/third_party/aom/av1/common/mvref_common.c b/third_party/aom/av1/common/mvref_common.c
new file mode 100644
index 000000000..5222948c8
--- /dev/null
+++ b/third_party/aom/av1/common/mvref_common.c
@@ -0,0 +1,1164 @@
+/*
+ * Copyright (c) 2016, Alliance for Open Media. All rights reserved
+ *
+ * This source code is subject to the terms of the BSD 2 Clause License and
+ * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
+ * was not distributed with this source code in the LICENSE file, you can
+ * obtain it at www.aomedia.org/license/software. If the Alliance for Open
+ * Media Patent License 1.0 was not distributed with this source code in the
+ * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
+ */
+
+#include "av1/common/mvref_common.h"
+#if CONFIG_WARPED_MOTION
+#include "av1/common/warped_motion.h"
+#endif  // CONFIG_WARPED_MOTION
+
+#if CONFIG_REF_MV
+
+static uint8_t add_ref_mv_candidate(
+    const MODE_INFO *const candidate_mi, const MB_MODE_INFO *const candidate,
+    const MV_REFERENCE_FRAME rf[2], uint8_t *refmv_count,
+    CANDIDATE_MV *ref_mv_stack, const int use_hp, int len, int block, int col) {
+  int index = 0, ref;
+  int newmv_count = 0;
+#if CONFIG_CB4X4
+  const int unify_bsize = 1;
+#else
+  const int unify_bsize = 0;
+#endif
+
+  if (rf[1] == NONE_FRAME) {
+    // single reference frame
+    for (ref = 0; ref < 2; ++ref) {
+      if (candidate->ref_frame[ref] == rf[0]) {
+        int_mv this_refmv = get_sub_block_mv(candidate_mi, ref, col, block);
+        lower_mv_precision(&this_refmv.as_mv, use_hp);
+
+        for (index = 0; index < *refmv_count; ++index)
+          if (ref_mv_stack[index].this_mv.as_int == this_refmv.as_int) break;
+
+        if (index < *refmv_count) ref_mv_stack[index].weight += 2 * len;
+
+        // Add a new item to the list.
+        if (index == *refmv_count) {
+          ref_mv_stack[index].this_mv = this_refmv;
+          ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
+              get_sub_block_pred_mv(candidate_mi, ref, col, block), this_refmv);
+          ref_mv_stack[index].weight = 2 * len;
+          ++(*refmv_count);
+
+          if (candidate->mode == NEWMV) ++newmv_count;
+        }
+
+        if (candidate_mi->mbmi.sb_type < BLOCK_8X8 && block >= 0 &&
+            !unify_bsize) {
+          int alt_block = 3 - block;
+          this_refmv = get_sub_block_mv(candidate_mi, ref, col, alt_block);
+          lower_mv_precision(&this_refmv.as_mv, use_hp);
+
+          for (index = 0; index < *refmv_count; ++index)
+            if (ref_mv_stack[index].this_mv.as_int == this_refmv.as_int) break;
+
+          if (index < *refmv_count) ref_mv_stack[index].weight += len;
+
+          // Add a new item to the list.
+          if (index == *refmv_count) {
+            ref_mv_stack[index].this_mv = this_refmv;
+            ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
+                get_sub_block_pred_mv(candidate_mi, ref, col, alt_block),
+                this_refmv);
+            ref_mv_stack[index].weight = len;
+            ++(*refmv_count);
+
+            if (candidate->mode == NEWMV) ++newmv_count;
+          }
+        }
+      }
+    }
+  } else {
+    // compound reference frame
+    if (candidate->ref_frame[0] == rf[0] && candidate->ref_frame[1] == rf[1]) {
+      int_mv this_refmv[2];
+
+      for (ref = 0; ref < 2; ++ref) {
+        this_refmv[ref] = get_sub_block_mv(candidate_mi, ref, col, block);
+        lower_mv_precision(&this_refmv[ref].as_mv, use_hp);
+      }
+
+      for (index = 0; index < *refmv_count; ++index)
+        if ((ref_mv_stack[index].this_mv.as_int == this_refmv[0].as_int) &&
+            (ref_mv_stack[index].comp_mv.as_int == this_refmv[1].as_int))
+          break;
+
+      if (index < *refmv_count) ref_mv_stack[index].weight += 2 * len;
+
+      // Add a new item to the list.
+      if (index == *refmv_count) {
+        ref_mv_stack[index].this_mv = this_refmv[0];
+        ref_mv_stack[index].comp_mv = this_refmv[1];
+        ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
+            get_sub_block_pred_mv(candidate_mi, 0, col, block), this_refmv[0]);
+        ref_mv_stack[index].pred_diff[1] = av1_get_pred_diff_ctx(
+            get_sub_block_pred_mv(candidate_mi, 1, col, block), this_refmv[1]);
+        ref_mv_stack[index].weight = 2 * len;
+        ++(*refmv_count);
+
+#if CONFIG_EXT_INTER
+        if (candidate->mode == NEW_NEWMV)
+#else
+        if (candidate->mode == NEWMV)
+#endif  // CONFIG_EXT_INTER
+          ++newmv_count;
+      }
+
+      if (candidate_mi->mbmi.sb_type < BLOCK_8X8 && block >= 0 &&
+          !unify_bsize) {
+        int alt_block = 3 - block;
+        this_refmv[0] = get_sub_block_mv(candidate_mi, 0, col, alt_block);
+        this_refmv[1] = get_sub_block_mv(candidate_mi, 1, col, alt_block);
+
+        for (ref = 0; ref < 2; ++ref)
+          lower_mv_precision(&this_refmv[ref].as_mv, use_hp);
+
+        for (index = 0; index < *refmv_count; ++index)
+          if (ref_mv_stack[index].this_mv.as_int == this_refmv[0].as_int &&
+              ref_mv_stack[index].comp_mv.as_int == this_refmv[1].as_int)
+            break;
+
+        if (index < *refmv_count) ref_mv_stack[index].weight += len;
+
+        // Add a new item to the list.
+        if (index == *refmv_count) {
+          ref_mv_stack[index].this_mv = this_refmv[0];
+          ref_mv_stack[index].comp_mv = this_refmv[1];
+          ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
+              get_sub_block_pred_mv(candidate_mi, 0, col, block),
+              this_refmv[0]);
+          ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
+              get_sub_block_pred_mv(candidate_mi, 1, col, block),
+              this_refmv[1]);
+          ref_mv_stack[index].weight = len;
+          ++(*refmv_count);
+
+#if CONFIG_EXT_INTER
+          if (candidate->mode == NEW_NEWMV)
+#else
+          if (candidate->mode == NEWMV)
+#endif  // CONFIG_EXT_INTER
+            ++newmv_count;
+        }
+      }
+    }
+  }
+  return newmv_count;
+}
+
+static uint8_t scan_row_mbmi(const AV1_COMMON *cm, const MACROBLOCKD *xd,
+                             const int mi_row, const int mi_col, int block,
+                             const MV_REFERENCE_FRAME rf[2], int row_offset,
+                             CANDIDATE_MV *ref_mv_stack, uint8_t *refmv_count) {
+  const TileInfo *const tile = &xd->tile;
+  int i;
+  uint8_t newmv_count = 0;
+#if CONFIG_CB4X4
+  const int bsize = xd->mi[0]->mbmi.sb_type;
+  const int mi_offset =
+      bsize < BLOCK_8X8 ? mi_size_wide[BLOCK_4X4] : mi_size_wide[BLOCK_8X8];
+  // TODO(jingning): Revisit this part after cb4x4 is stable.
+  if (bsize >= BLOCK_8X8) row_offset *= 2;
+#else
+  const int mi_offset = mi_size_wide[BLOCK_8X8];
+#endif
+
+  for (i = 0; i < xd->n8_w && *refmv_count < MAX_REF_MV_STACK_SIZE;) {
+    POSITION mi_pos;
+#if CONFIG_CB4X4
+    const int use_step_16 = (xd->n8_w >= 16);
+#else
+    const int use_step_16 = (xd->n8_w >= 8);
+#endif
+
+    mi_pos.row = row_offset;
+    mi_pos.col = i;
+    if (is_inside(tile, mi_col, mi_row, cm->mi_rows, cm, &mi_pos)) {
+      const MODE_INFO *const candidate_mi =
+          xd->mi[mi_pos.row * xd->mi_stride + mi_pos.col];
+      const MB_MODE_INFO *const candidate = &candidate_mi->mbmi;
+      int len = AOMMIN(xd->n8_w, mi_size_wide[candidate->sb_type]);
+      if (use_step_16) len = AOMMAX(mi_size_wide[BLOCK_16X16], len);
+      newmv_count += add_ref_mv_candidate(
+          candidate_mi, candidate, rf, refmv_count, ref_mv_stack,
+          cm->allow_high_precision_mv, len, block, mi_pos.col);
+      i += len;
+    } else {
+      if (use_step_16)
+        i += (mi_offset << 1);
+      else
+        i += mi_offset;
+    }
+  }
+
+  return newmv_count;
+}
+
+static uint8_t scan_col_mbmi(const AV1_COMMON *cm, const MACROBLOCKD *xd,
+                             const int mi_row, const int mi_col, int block,
+                             const MV_REFERENCE_FRAME rf[2], int col_offset,
+                             CANDIDATE_MV *ref_mv_stack, uint8_t *refmv_count) {
+  const TileInfo *const tile = &xd->tile;
+  int i;
+  uint8_t newmv_count = 0;
+#if CONFIG_CB4X4
+  const BLOCK_SIZE bsize = xd->mi[0]->mbmi.sb_type;
+  const int mi_offset =
+      (bsize < BLOCK_8X8) ? mi_size_high[BLOCK_4X4] : mi_size_high[BLOCK_8X8];
+  if (bsize >= BLOCK_8X8) col_offset *= 2;
+#else
+  const int mi_offset = mi_size_wide[BLOCK_8X8];
+#endif
+
+  for (i = 0; i < xd->n8_h && *refmv_count < MAX_REF_MV_STACK_SIZE;) {
+    POSITION mi_pos;
+#if CONFIG_CB4X4
+    const int use_step_16 = (xd->n8_h >= 16);
+#else
+    const int use_step_16 = (xd->n8_h >= 8);
+#endif
+
+    mi_pos.row = i;
+    mi_pos.col = col_offset;
+    if (is_inside(tile, mi_col, mi_row, cm->mi_rows, cm, &mi_pos)) {
+      const MODE_INFO *const candidate_mi =
+          xd->mi[mi_pos.row * xd->mi_stride + mi_pos.col];
+      const MB_MODE_INFO *const candidate = &candidate_mi->mbmi;
+      int len = AOMMIN(xd->n8_h, mi_size_high[candidate->sb_type]);
+      if (use_step_16) len = AOMMAX(mi_size_high[BLOCK_16X16], len);
+      newmv_count += add_ref_mv_candidate(
+          candidate_mi, candidate, rf, refmv_count, ref_mv_stack,
+          cm->allow_high_precision_mv, len, block, mi_pos.col);
+      i += len;
+    } else {
+      if (use_step_16)
+        i += (mi_offset << 1);
+      else
+        i += mi_offset;
+    }
+  }
+
+  return newmv_count;
+}
+
+static uint8_t scan_blk_mbmi(const AV1_COMMON *cm, const MACROBLOCKD *xd,
+                             const int mi_row, const int mi_col, int block,
+                             const MV_REFERENCE_FRAME rf[2], int row_offset,
+                             int col_offset, CANDIDATE_MV *ref_mv_stack,
+                             uint8_t *refmv_count) {
+  const TileInfo *const tile = &xd->tile;
+  POSITION mi_pos;
+  uint8_t newmv_count = 0;
+
+  mi_pos.row = row_offset;
+  mi_pos.col = col_offset;
+
+  if (is_inside(tile, mi_col, mi_row, cm->mi_rows, cm, &mi_pos) &&
+      *refmv_count < MAX_REF_MV_STACK_SIZE) {
+    const MODE_INFO *const candidate_mi =
+        xd->mi[mi_pos.row * xd->mi_stride + mi_pos.col];
+    const MB_MODE_INFO *const candidate = &candidate_mi->mbmi;
+    const int len = mi_size_wide[BLOCK_8X8];
+
+    newmv_count += add_ref_mv_candidate(
+        candidate_mi, candidate, rf, refmv_count, ref_mv_stack,
+        cm->allow_high_precision_mv, len, block, mi_pos.col);
+  }  // Analyze a single 8x8 block motion information.
+
+  return newmv_count;
+}
+
+static int has_top_right(const MACROBLOCKD *xd, int mi_row, int mi_col,
+                         int bs) {
+  const int mask_row = mi_row & MAX_MIB_MASK;
+  const int mask_col = mi_col & MAX_MIB_MASK;
+
+  // In a split partition all apart from the bottom right has a top right
+  int has_tr = !((mask_row & bs) && (mask_col & bs));
+
+  // bs > 0 and bs is a power of 2
+  assert(bs > 0 && !(bs & (bs - 1)));
+
+  // For each 4x4 group of blocks, when the bottom right is decoded the blocks
+  // to the right have not been decoded therefore the bottom right does
+  // not have a top right
+  while (bs < MAX_MIB_SIZE) {
+    if (mask_col & bs) {
+      if ((mask_col & (2 * bs)) && (mask_row & (2 * bs))) {
+        has_tr = 0;
+        break;
+      }
+    } else {
+      break;
+    }
+    bs <<= 1;
+  }
+
+  // The left hand of two vertical rectangles always has a top right (as the
+  // block above will have been decoded)
+  if (xd->n8_w < xd->n8_h)
+    if (!xd->is_sec_rect) has_tr = 1;
+
+  // The bottom of two horizontal rectangles never has a top right (as the block
+  // to the right won't have been decoded)
+  if (xd->n8_w > xd->n8_h)
+    if (xd->is_sec_rect) has_tr = 0;
+
+#if CONFIG_EXT_PARTITION_TYPES
+  // The bottom left square of a Vertical A does not have a top right as it is
+  // decoded before the right hand rectangle of the partition
+  if (xd->mi[0]->mbmi.partition == PARTITION_VERT_A)
+    if ((mask_row & bs) && !(mask_col & bs)) has_tr = 0;
+#endif  // CONFIG_EXT_PARTITION_TYPES
+
+  return has_tr;
+}
+
+static int add_col_ref_mv(const AV1_COMMON *cm,
+                          const MV_REF *prev_frame_mvs_base,
+                          const MACROBLOCKD *xd, int mi_row, int mi_col,
+                          MV_REFERENCE_FRAME ref_frame, int blk_row,
+                          int blk_col, uint8_t *refmv_count,
+                          CANDIDATE_MV *ref_mv_stack, int16_t *mode_context) {
+  const MV_REF *prev_frame_mvs =
+      prev_frame_mvs_base + blk_row * cm->mi_cols + blk_col;
+  POSITION mi_pos;
+  int ref, idx;
+  int coll_blk_count = 0;
+  const int weight_unit = mi_size_wide[BLOCK_8X8];
+
+#if CONFIG_MV_COMPRESS
+  mi_pos.row = (mi_row & 0x01) ? blk_row : blk_row + 1;
+  mi_pos.col = (mi_col & 0x01) ? blk_col : blk_col + 1;
+#else
+  mi_pos.row = blk_row;
+  mi_pos.col = blk_col;
+#endif
+
+  if (!is_inside(&xd->tile, mi_col, mi_row, cm->mi_rows, cm, &mi_pos))
+    return coll_blk_count;
+  for (ref = 0; ref < 2; ++ref) {
+    if (prev_frame_mvs->ref_frame[ref] == ref_frame) {
+      int_mv this_refmv = prev_frame_mvs->mv[ref];
+      lower_mv_precision(&this_refmv.as_mv, cm->allow_high_precision_mv);
+
+      if (abs(this_refmv.as_mv.row) >= 16 || abs(this_refmv.as_mv.col) >= 16)
+        mode_context[ref_frame] |= (1 << ZEROMV_OFFSET);
+
+      for (idx = 0; idx < *refmv_count; ++idx)
+        if (this_refmv.as_int == ref_mv_stack[idx].this_mv.as_int) break;
+
+      if (idx < *refmv_count) ref_mv_stack[idx].weight += 2 * weight_unit;
+
+      if (idx == *refmv_count && *refmv_count < MAX_REF_MV_STACK_SIZE) {
+        ref_mv_stack[idx].this_mv.as_int = this_refmv.as_int;
+        ref_mv_stack[idx].pred_diff[0] =
+            av1_get_pred_diff_ctx(prev_frame_mvs->pred_mv[ref], this_refmv);
+        ref_mv_stack[idx].weight = 2 * weight_unit;
+        ++(*refmv_count);
+      }
+
+      ++coll_blk_count;
+    }
+  }
+
+  return coll_blk_count;
+}
+
+static void setup_ref_mv_list(const AV1_COMMON *cm, const MACROBLOCKD *xd,
+                              MV_REFERENCE_FRAME ref_frame,
+                              uint8_t *refmv_count, CANDIDATE_MV *ref_mv_stack,
+                              int_mv *mv_ref_list, int block, int mi_row,
+                              int mi_col, int16_t *mode_context) {
+  int idx, nearest_refmv_count = 0;
+  uint8_t newmv_count = 0;
+  CANDIDATE_MV tmp_mv;
+  int len, nr_len;
+
+#if CONFIG_MV_COMPRESS
+  const MV_REF *const prev_frame_mvs_base =
+      cm->use_prev_frame_mvs
+          ? cm->prev_frame->mvs + (((mi_row >> 1) << 1) + 1) * cm->mi_cols +
+                ((mi_col >> 1) << 1) + 1
+          : NULL;
+#else
+  const MV_REF *const prev_frame_mvs_base =
+      cm->use_prev_frame_mvs
+          ? cm->prev_frame->mvs + mi_row * cm->mi_cols + mi_col
+          : NULL;
+#endif
+
+  const int bs = AOMMAX(xd->n8_w, xd->n8_h);
+  const int has_tr = has_top_right(xd, mi_row, mi_col, bs);
+  MV_REFERENCE_FRAME rf[2];
+
+  av1_set_ref_frame(rf, ref_frame);
+  mode_context[ref_frame] = 0;
+  *refmv_count = 0;
+
+  // Scan the first above row mode info.
+  newmv_count += scan_row_mbmi(cm, xd, mi_row, mi_col, block, rf, -1,
+                               ref_mv_stack, refmv_count);
+  // Scan the first left column mode info.
+  newmv_count += scan_col_mbmi(cm, xd, mi_row, mi_col, block, rf, -1,
+                               ref_mv_stack, refmv_count);
+
+  // Check top-right boundary
+  if (has_tr)
+    newmv_count += scan_blk_mbmi(cm, xd, mi_row, mi_col, block, rf, -1,
+                                 xd->n8_w, ref_mv_stack, refmv_count);
+
+  nearest_refmv_count = *refmv_count;
+
+  for (idx = 0; idx < nearest_refmv_count; ++idx)
+    ref_mv_stack[idx].weight += REF_CAT_LEVEL;
+#if CONFIG_TEMPMV_SIGNALING
+  if (cm->use_prev_frame_mvs && rf[1] == NONE_FRAME) {
+#else
+  if (prev_frame_mvs_base && cm->show_frame && cm->last_show_frame &&
+      rf[1] == NONE_FRAME) {
+#endif
+    int blk_row, blk_col;
+    int coll_blk_count = 0;
+#if CONFIG_CB4X4
+    const int mi_step = (xd->n8_w == 1 || xd->n8_h == 1)
+                            ? mi_size_wide[BLOCK_8X8]
+                            : mi_size_wide[BLOCK_16X16];
+#else
+    const int mi_step = mi_size_wide[BLOCK_16X16];
+#endif
+
+#if CONFIG_TPL_MV
+    int tpl_sample_pos[5][2] = { { -1, xd->n8_w },
+                                 { 0, xd->n8_w },
+                                 { xd->n8_h, xd->n8_w },
+                                 { xd->n8_h, 0 },
+                                 { xd->n8_h, -1 } };
+    int i;
+#endif
+
+    for (blk_row = 0; blk_row < xd->n8_h; blk_row += mi_step) {
+      for (blk_col = 0; blk_col < xd->n8_w; blk_col += mi_step) {
+        coll_blk_count += add_col_ref_mv(
+            cm, prev_frame_mvs_base, xd, mi_row, mi_col, ref_frame, blk_row,
+            blk_col, refmv_count, ref_mv_stack, mode_context);
+      }
+    }
+
+#if CONFIG_TPL_MV
+    for (i = 0; i < 5; ++i) {
+      blk_row = tpl_sample_pos[i][0];
+      blk_col = tpl_sample_pos[i][1];
+      coll_blk_count += add_col_ref_mv(cm, prev_frame_mvs_base, xd, mi_row,
+                                       mi_col, ref_frame, blk_row, blk_col,
+                                       refmv_count, ref_mv_stack, mode_context);
+    }
+#endif
+
+    if (coll_blk_count == 0) mode_context[ref_frame] |= (1 << ZEROMV_OFFSET);
+  } else {
+    mode_context[ref_frame] |= (1 << ZEROMV_OFFSET);
+  }
+
+  // Scan the second outer area.
+  scan_blk_mbmi(cm, xd, mi_row, mi_col, block, rf, -1, -1, ref_mv_stack,
+                refmv_count);
+  for (idx = 2; idx <= 3; ++idx) {
+    scan_row_mbmi(cm, xd, mi_row, mi_col, block, rf, -idx, ref_mv_stack,
+                  refmv_count);
+    scan_col_mbmi(cm, xd, mi_row, mi_col, block, rf, -idx, ref_mv_stack,
+                  refmv_count);
+  }
+  scan_col_mbmi(cm, xd, mi_row, mi_col, block, rf, -4, ref_mv_stack,
+                refmv_count);
+
+  switch (nearest_refmv_count) {
+    case 0:
+      mode_context[ref_frame] |= 0;
+      if (*refmv_count >= 1) mode_context[ref_frame] |= 1;
+
+      if (*refmv_count == 1)
+        mode_context[ref_frame] |= (1 << REFMV_OFFSET);
+      else if (*refmv_count >= 2)
+        mode_context[ref_frame] |= (2 << REFMV_OFFSET);
+      break;
+    case 1:
+      mode_context[ref_frame] |= (newmv_count > 0) ? 2 : 3;
+
+      if (*refmv_count == 1)
+        mode_context[ref_frame] |= (3 << REFMV_OFFSET);
+      else if (*refmv_count >= 2)
+        mode_context[ref_frame] |= (4 << REFMV_OFFSET);
+      break;
+
+    case 2:
+    default:
+      if (newmv_count >= 2)
+        mode_context[ref_frame] |= 4;
+      else if (newmv_count == 1)
+        mode_context[ref_frame] |= 5;
+      else
+        mode_context[ref_frame] |= 6;
+
+      mode_context[ref_frame] |= (5 << REFMV_OFFSET);
+      break;
+  }
+
+  // Rank the likelihood and assign nearest and near mvs.
+  len = nearest_refmv_count;
+  while (len > 0) {
+    nr_len = 0;
+    for (idx = 1; idx < len; ++idx) {
+      if (ref_mv_stack[idx - 1].weight < ref_mv_stack[idx].weight) {
+        tmp_mv = ref_mv_stack[idx - 1];
+        ref_mv_stack[idx - 1] = ref_mv_stack[idx];
+        ref_mv_stack[idx] = tmp_mv;
+        nr_len = idx;
+      }
+    }
+    len = nr_len;
+  }
+
+  len = *refmv_count;
+  while (len > nearest_refmv_count) {
+    nr_len = nearest_refmv_count;
+    for (idx = nearest_refmv_count + 1; idx < len; ++idx) {
+      if (ref_mv_stack[idx - 1].weight < ref_mv_stack[idx].weight) {
+        tmp_mv = ref_mv_stack[idx - 1];
+        ref_mv_stack[idx - 1] = ref_mv_stack[idx];
+        ref_mv_stack[idx] = tmp_mv;
+        nr_len = idx;
+      }
+    }
+    len = nr_len;
+  }
+
+  if (rf[1] > NONE_FRAME) {
+    for (idx = 0; idx < *refmv_count; ++idx) {
+      clamp_mv_ref(&ref_mv_stack[idx].this_mv.as_mv, xd->n8_w << MI_SIZE_LOG2,
+                   xd->n8_h << MI_SIZE_LOG2, xd);
+      clamp_mv_ref(&ref_mv_stack[idx].comp_mv.as_mv, xd->n8_w << MI_SIZE_LOG2,
+                   xd->n8_h << MI_SIZE_LOG2, xd);
+    }
+  } else {
+    for (idx = 0; idx < AOMMIN(MAX_MV_REF_CANDIDATES, *refmv_count); ++idx) {
+      mv_ref_list[idx].as_int = ref_mv_stack[idx].this_mv.as_int;
+      clamp_mv_ref(&mv_ref_list[idx].as_mv, xd->n8_w << MI_SIZE_LOG2,
+                   xd->n8_h << MI_SIZE_LOG2, xd);
+    }
+  }
+}
+#endif
+
+// This function searches the neighbourhood of a given MB/SB
+// to try and find candidate reference vectors.
+static void find_mv_refs_idx(const AV1_COMMON *cm, const MACROBLOCKD *xd,
+                             MODE_INFO *mi, MV_REFERENCE_FRAME ref_frame,
+                             int_mv *mv_ref_list, int block, int mi_row,
+                             int mi_col, find_mv_refs_sync sync,
+                             void *const data, int16_t *mode_context,
+                             int_mv zeromv) {
+  const int *ref_sign_bias = cm->ref_frame_sign_bias;
+  int i, refmv_count = 0;
+#if !CONFIG_REF_MV
+  const POSITION *const mv_ref_search = mv_ref_blocks[mi->mbmi.sb_type];
+#endif
+  int different_ref_found = 0;
+  int context_counter = 0;
+#if CONFIG_MV_COMPRESS
+  const TileInfo *const tile_ = &xd->tile;
+  int mi_row_end = tile_->mi_row_end;
+  int mi_col_end = tile_->mi_col_end;
+  const MV_REF *const prev_frame_mvs =
+      cm->use_prev_frame_mvs
+          ? cm->prev_frame->mvs +
+                AOMMIN(((mi_row >> 1) << 1) + 1 + (((xd->n8_h - 1) >> 1) << 1),
+                       mi_row_end - 1) *
+                    cm->mi_cols +
+                AOMMIN(((mi_col >> 1) << 1) + 1 + (((xd->n8_w - 1) >> 1) << 1),
+                       mi_col_end - 1)
+          : NULL;
+#else
+  const MV_REF *const prev_frame_mvs =
+      cm->use_prev_frame_mvs
+          ? cm->prev_frame->mvs + mi_row * cm->mi_cols + mi_col
+          : NULL;
+#endif
+  const TileInfo *const tile = &xd->tile;
+  const BLOCK_SIZE bsize = mi->mbmi.sb_type;
+  const int bw = block_size_wide[AOMMAX(bsize, BLOCK_8X8)];
+  const int bh = block_size_high[AOMMAX(bsize, BLOCK_8X8)];
+#if CONFIG_REF_MV
+  POSITION mv_ref_search[MVREF_NEIGHBOURS];
+  const int num_8x8_blocks_wide = num_8x8_blocks_wide_lookup[bsize];
+  const int num_8x8_blocks_high = num_8x8_blocks_high_lookup[bsize];
+  mv_ref_search[0].row = num_8x8_blocks_high - 1;
+  mv_ref_search[0].col = -1;
+  mv_ref_search[1].row = -1;
+  mv_ref_search[1].col = num_8x8_blocks_wide - 1;
+  mv_ref_search[2].row = -1;
+  mv_ref_search[2].col = (num_8x8_blocks_wide - 1) >> 1;
+  mv_ref_search[3].row = (num_8x8_blocks_high - 1) >> 1;
+  mv_ref_search[3].col = -1;
+  mv_ref_search[4].row = -1;
+  mv_ref_search[4].col = -1;
+#if CONFIG_EXT_PARTITION_TYPES
+  if (num_8x8_blocks_wide == num_8x8_blocks_high) {
+    mv_ref_search[5].row = -1;
+    mv_ref_search[5].col = 0;
+    mv_ref_search[6].row = 0;
+    mv_ref_search[6].col = -1;
+  } else {
+    mv_ref_search[5].row = -1;
+    mv_ref_search[5].col = num_8x8_blocks_wide;
+    mv_ref_search[6].row = num_8x8_blocks_high;
+    mv_ref_search[6].col = -1;
+  }
+#else
+  mv_ref_search[5].row = -1;
+  mv_ref_search[5].col = num_8x8_blocks_wide;
+  mv_ref_search[6].row = num_8x8_blocks_high;
+  mv_ref_search[6].col = -1;
+#endif  // CONFIG_EXT_PARTITION_TYPES
+  mv_ref_search[7].row = -1;
+  mv_ref_search[7].col = -3;
+  mv_ref_search[8].row = num_8x8_blocks_high - 1;
+  mv_ref_search[8].col = -3;
+
+#if CONFIG_CB4X4
+  for (i = 0; i < MVREF_NEIGHBOURS; ++i) {
+    mv_ref_search[i].row *= 2;
+    mv_ref_search[i].col *= 2;
+  }
+#endif  // CONFIG_CB4X4
+#endif  // CONFIG_REF_MV
+
+  // The nearest 2 blocks are treated differently
+  // if the size < 8x8 we get the mv from the bmi substructure,
+  // and we also need to keep a mode count.
+  for (i = 0; i < 2; ++i) {
+    const POSITION *const mv_ref = &mv_ref_search[i];
+    if (is_inside(tile, mi_col, mi_row, cm->mi_rows, cm, mv_ref)) {
+      const MODE_INFO *const candidate_mi =
+          xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride];
+      const MB_MODE_INFO *const candidate = &candidate_mi->mbmi;
+      // Keep counts for entropy encoding.
+      context_counter += mode_2_counter[candidate->mode];
+      different_ref_found = 1;
+
+      if (candidate->ref_frame[0] == ref_frame)
+        ADD_MV_REF_LIST(get_sub_block_mv(candidate_mi, 0, mv_ref->col, block),
+                        refmv_count, mv_ref_list, bw, bh, xd, Done);
+      else if (candidate->ref_frame[1] == ref_frame)
+        ADD_MV_REF_LIST(get_sub_block_mv(candidate_mi, 1, mv_ref->col, block),
+                        refmv_count, mv_ref_list, bw, bh, xd, Done);
+    }
+  }
+
+  // Check the rest of the neighbors in much the same way
+  // as before except we don't need to keep track of sub blocks or
+  // mode counts.
+  for (; i < MVREF_NEIGHBOURS; ++i) {
+    const POSITION *const mv_ref = &mv_ref_search[i];
+    if (is_inside(tile, mi_col, mi_row, cm->mi_rows, cm, mv_ref)) {
+      const MB_MODE_INFO *const candidate =
+          !xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride]
+              ? NULL
+              : &xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride]->mbmi;
+#if CONFIG_REF_MV
+      if (candidate == NULL) continue;
+      if ((mi_row % MAX_MIB_SIZE) + mv_ref->row >= MAX_MIB_SIZE ||
+          (mi_col % MAX_MIB_SIZE) + mv_ref->col >= MAX_MIB_SIZE)
+        continue;
+#endif
+      different_ref_found = 1;
+
+      if (candidate->ref_frame[0] == ref_frame)
+        ADD_MV_REF_LIST(candidate->mv[0], refmv_count, mv_ref_list, bw, bh, xd,
+                        Done);
+      else if (candidate->ref_frame[1] == ref_frame)
+        ADD_MV_REF_LIST(candidate->mv[1], refmv_count, mv_ref_list, bw, bh, xd,
+                        Done);
+    }
+  }
+
+// TODO(hkuang): Remove this sync after fixing pthread_cond_broadcast
+// on windows platform. The sync here is unncessary if use_perv_frame_mvs
+// is 0. But after removing it, there will be hang in the unit test on windows
+// due to several threads waiting for a thread's signal.
+#if defined(_WIN32) && !HAVE_PTHREAD_H
+  if (cm->frame_parallel_decode && sync != NULL) {
+    sync(data, mi_row);
+  }
+#endif
+
+  // Check the last frame's mode and mv info.
+  if (cm->use_prev_frame_mvs) {
+    // Synchronize here for frame parallel decode if sync function is provided.
+    if (cm->frame_parallel_decode && sync != NULL) {
+      sync(data, mi_row);
+    }
+
+    if (prev_frame_mvs->ref_frame[0] == ref_frame) {
+      ADD_MV_REF_LIST(prev_frame_mvs->mv[0], refmv_count, mv_ref_list, bw, bh,
+                      xd, Done);
+    } else if (prev_frame_mvs->ref_frame[1] == ref_frame) {
+      ADD_MV_REF_LIST(prev_frame_mvs->mv[1], refmv_count, mv_ref_list, bw, bh,
+                      xd, Done);
+    }
+  }
+
+  // Since we couldn't find 2 mvs from the same reference frame
+  // go back through the neighbors and find motion vectors from
+  // different reference frames.
+  if (different_ref_found) {
+    for (i = 0; i < MVREF_NEIGHBOURS; ++i) {
+      const POSITION *mv_ref = &mv_ref_search[i];
+      if (is_inside(tile, mi_col, mi_row, cm->mi_rows, cm, mv_ref)) {
+        const MB_MODE_INFO *const candidate =
+            !xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride]
+                ? NULL
+                : &xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride]->mbmi;
+#if CONFIG_REF_MV
+        if (candidate == NULL) continue;
+        if ((mi_row % MAX_MIB_SIZE) + mv_ref->row >= MAX_MIB_SIZE ||
+            (mi_col % MAX_MIB_SIZE) + mv_ref->col >= MAX_MIB_SIZE)
+          continue;
+#endif
+
+        // If the candidate is INTRA we don't want to consider its mv.
+        IF_DIFF_REF_FRAME_ADD_MV(candidate, ref_frame, ref_sign_bias,
+                                 refmv_count, mv_ref_list, bw, bh, xd, Done);
+      }
+    }
+  }
+
+  // Since we still don't have a candidate we'll try the last frame.
+  if (cm->use_prev_frame_mvs) {
+    if (prev_frame_mvs->ref_frame[0] != ref_frame &&
+        prev_frame_mvs->ref_frame[0] > INTRA_FRAME) {
+      int_mv mv = prev_frame_mvs->mv[0];
+      if (ref_sign_bias[prev_frame_mvs->ref_frame[0]] !=
+          ref_sign_bias[ref_frame]) {
+        mv.as_mv.row *= -1;
+        mv.as_mv.col *= -1;
+      }
+      ADD_MV_REF_LIST(mv, refmv_count, mv_ref_list, bw, bh, xd, Done);
+    }
+
+    if (prev_frame_mvs->ref_frame[1] > INTRA_FRAME &&
+        prev_frame_mvs->ref_frame[1] != ref_frame) {
+      int_mv mv = prev_frame_mvs->mv[1];
+      if (ref_sign_bias[prev_frame_mvs->ref_frame[1]] !=
+          ref_sign_bias[ref_frame]) {
+        mv.as_mv.row *= -1;
+        mv.as_mv.col *= -1;
+      }
+      ADD_MV_REF_LIST(mv, refmv_count, mv_ref_list, bw, bh, xd, Done);
+    }
+  }
+
+Done:
+  if (mode_context)
+    mode_context[ref_frame] = counter_to_context[context_counter];
+  for (i = refmv_count; i < MAX_MV_REF_CANDIDATES; ++i)
+    mv_ref_list[i].as_int = zeromv.as_int;
+}
+
+#if CONFIG_EXT_INTER
+// This function keeps a mode count for a given MB/SB
+void av1_update_mv_context(const AV1_COMMON *cm, const MACROBLOCKD *xd,
+                           MODE_INFO *mi, MV_REFERENCE_FRAME ref_frame,
+                           int_mv *mv_ref_list, int block, int mi_row,
+                           int mi_col, int16_t *mode_context) {
+  int i, refmv_count = 0;
+#if !CONFIG_REF_MV
+  const POSITION *const mv_ref_search = mv_ref_blocks[mi->mbmi.sb_type];
+#endif
+  int context_counter = 0;
+  const int bw = block_size_wide[mi->mbmi.sb_type];
+  const int bh = block_size_high[mi->mbmi.sb_type];
+  const TileInfo *const tile = &xd->tile;
+#if CONFIG_REF_MV
+  POSITION mv_ref_search[MVREF_NEIGHBOURS];
+  const int num_8x8_blocks_wide = mi_size_wide[mi->mbmi.sb_type];
+  const int num_8x8_blocks_high = mi_size_high[mi->mbmi.sb_type];
+  mv_ref_search[0].row = num_8x8_blocks_high - 1;
+  mv_ref_search[0].col = -1;
+  mv_ref_search[1].row = -1;
+  mv_ref_search[1].col = num_8x8_blocks_wide - 1;
+  mv_ref_search[2].row = -1;
+  mv_ref_search[2].col = (num_8x8_blocks_wide - 1) >> 1;
+  mv_ref_search[3].row = (num_8x8_blocks_high - 1) >> 1;
+  mv_ref_search[3].col = -1;
+  mv_ref_search[4].row = -1;
+  mv_ref_search[4].col = -1;
+#if CONFIG_EXT_PARTITION_TYPES
+  if (num_8x8_blocks_wide == num_8x8_blocks_high) {
+    mv_ref_search[5].row = -1;
+    mv_ref_search[5].col = 0;
+    mv_ref_search[6].row = 0;
+    mv_ref_search[6].col = -1;
+  } else {
+    mv_ref_search[5].row = -1;
+    mv_ref_search[5].col = num_8x8_blocks_wide;
+    mv_ref_search[6].row = num_8x8_blocks_high;
+    mv_ref_search[6].col = -1;
+  }
+#else
+  mv_ref_search[5].row = -1;
+  mv_ref_search[5].col = num_8x8_blocks_wide;
+  mv_ref_search[6].row = num_8x8_blocks_high;
+  mv_ref_search[6].col = -1;
+#endif  // CONFIG_EXT_PARTITION_TYPES
+  mv_ref_search[7].row = -1;
+  mv_ref_search[7].col = -3;
+  mv_ref_search[8].row = num_8x8_blocks_high - 1;
+  mv_ref_search[8].col = -3;
+#endif
+
+  // Blank the reference vector list
+  memset(mv_ref_list, 0, sizeof(*mv_ref_list) * MAX_MV_REF_CANDIDATES);
+
+  // The nearest 2 blocks are examined only.
+  // If the size < 8x8, we get the mv from the bmi substructure;
+  for (i = 0; i < 2; ++i) {
+    const POSITION *const mv_ref = &mv_ref_search[i];
+    if (is_inside(tile, mi_col, mi_row, cm->mi_rows, cm, mv_ref)) {
+      const MODE_INFO *const candidate_mi =
+          xd->mi[mv_ref->col + mv_ref->row * xd->mi_stride];
+      const MB_MODE_INFO *const candidate = &candidate_mi->mbmi;
+
+      // Keep counts for entropy encoding.
+      context_counter += mode_2_counter[candidate->mode];
+
+      if (candidate->ref_frame[0] == ref_frame) {
+        ADD_MV_REF_LIST(get_sub_block_mv(candidate_mi, 0, mv_ref->col, block),
+                        refmv_count, mv_ref_list, bw, bh, xd, Done);
+      } else if (candidate->ref_frame[1] == ref_frame) {
+        ADD_MV_REF_LIST(get_sub_block_mv(candidate_mi, 1, mv_ref->col, block),
+                        refmv_count, mv_ref_list, bw, bh, xd, Done);
+      }
+    }
+  }
+
+Done:
+
+  if (mode_context)
+    mode_context[ref_frame] = counter_to_context[context_counter];
+}
+#endif  // CONFIG_EXT_INTER
+
+void av1_find_mv_refs(const AV1_COMMON *cm, const MACROBLOCKD *xd,
+                      MODE_INFO *mi, MV_REFERENCE_FRAME ref_frame,
+#if CONFIG_REF_MV
+                      uint8_t *ref_mv_count, CANDIDATE_MV *ref_mv_stack,
+#if CONFIG_EXT_INTER
+                      int16_t *compound_mode_context,
+#endif  // CONFIG_EXT_INTER
+#endif
+                      int_mv *mv_ref_list, int mi_row, int mi_col,
+                      find_mv_refs_sync sync, void *const data,
+                      int16_t *mode_context) {
+  int_mv zeromv[2];
+#if CONFIG_GLOBAL_MOTION
+  BLOCK_SIZE bsize = mi->mbmi.sb_type;
+#endif  // CONFIG_GLOBAL_MOTION
+#if CONFIG_REF_MV
+  int idx, all_zero = 1;
+#if CONFIG_GLOBAL_MOTION
+  MV_REFERENCE_FRAME rf[2];
+#endif  // CONFIG_GLOBAL_MOTION
+#endif  // CONFIG_REF_MV
+#if CONFIG_EXT_INTER
+  av1_update_mv_context(cm, xd, mi, ref_frame, mv_ref_list, -1, mi_row, mi_col,
+#if CONFIG_REF_MV
+                        compound_mode_context);
+#else
+                        mode_context);
+#endif  // CONFIG_REF_MV
+#endif  // CONFIG_EXT_INTER
+
+#if CONFIG_GLOBAL_MOTION
+#if CONFIG_REF_MV
+  av1_set_ref_frame(rf, ref_frame);
+  zeromv[0].as_int = gm_get_motion_vector(&cm->global_motion[rf[0]],
+                                          cm->allow_high_precision_mv, bsize,
+                                          mi_col, mi_row, 0)
+                         .as_int;
+  zeromv[1].as_int = (rf[1] != NONE_FRAME)
+                         ? gm_get_motion_vector(&cm->global_motion[rf[1]],
+                                                cm->allow_high_precision_mv,
+                                                bsize, mi_col, mi_row, 0)
+                               .as_int
+                         : 0;
+#else
+  zeromv[0].as_int = gm_get_motion_vector(&cm->global_motion[ref_frame],
+                                          cm->allow_high_precision_mv, bsize,
+                                          mi_col, mi_row, 0)
+                         .as_int;
+  zeromv[1].as_int = 0;
+#endif  // CONFIG_REF_MV
+#else
+  zeromv[0].as_int = zeromv[1].as_int = 0;
+#endif  // CONFIG_GLOBAL_MOTION
+
+#if CONFIG_REF_MV
+  if (ref_frame <= ALTREF_FRAME)
+#endif  // CONFIG_REF_MV
+    find_mv_refs_idx(cm, xd, mi, ref_frame, mv_ref_list, -1, mi_row, mi_col,
+                     sync, data, mode_context, zeromv[0]);
+
+#if CONFIG_REF_MV
+  setup_ref_mv_list(cm, xd, ref_frame, ref_mv_count, ref_mv_stack, mv_ref_list,
+                    -1, mi_row, mi_col, mode_context);
+  /* Note: If global motion is enabled, then we want to set the ALL_ZERO flag
+     iff all of the MVs we could generate with NEARMV/NEARESTMV are equivalent
+     to the global motion vector.
+     Note: For the following to work properly, the encoder can't throw away
+     any global motion models after calling this function, even if they are
+     unused. Instead we rely on the recode loop: If any non-IDENTITY model
+     is unused, the whole frame will be re-encoded without it.
+     The problem is that, otherwise, we can end up in the following situation:
+     * Encoder has a global motion model with nonzero translational part,
+       and all candidate MVs are zero. So the ALL_ZERO flag is unset.
+     * Encoder throws away global motion because it is never used.
+     * Decoder sees that there is no global motion and all candidate MVs are
+       zero, so sets the ALL_ZERO flag.
+     * This leads to an encode/decode mismatch.
+  */
+  if (*ref_mv_count >= 2) {
+    for (idx = 0; idx < AOMMIN(3, *ref_mv_count); ++idx) {
+      if (ref_mv_stack[idx].this_mv.as_int != zeromv[0].as_int) all_zero = 0;
+      if (ref_frame > ALTREF_FRAME)
+        if (ref_mv_stack[idx].comp_mv.as_int != zeromv[1].as_int) all_zero = 0;
+    }
+  } else if (ref_frame <= ALTREF_FRAME) {
+    for (idx = 0; idx < MAX_MV_REF_CANDIDATES; ++idx)
+      if (mv_ref_list[idx].as_int != zeromv[0].as_int) all_zero = 0;
+  }
+
+  if (all_zero) mode_context[ref_frame] |= (1 << ALL_ZERO_FLAG_OFFSET);
+#endif
+}
+
+void av1_find_best_ref_mvs(int allow_hp, int_mv *mvlist, int_mv *nearest_mv,
+                           int_mv *near_mv) {
+  int i;
+  // Make sure all the candidates are properly clamped etc
+  for (i = 0; i < MAX_MV_REF_CANDIDATES; ++i) {
+    lower_mv_precision(&mvlist[i].as_mv, allow_hp);
+  }
+  *nearest_mv = mvlist[0];
+  *near_mv = mvlist[1];
+}
+
+void av1_append_sub8x8_mvs_for_idx(const AV1_COMMON *cm, MACROBLOCKD *xd,
+                                   int block, int ref, int mi_row, int mi_col,
+#if CONFIG_REF_MV
+                                   CANDIDATE_MV *ref_mv_stack,
+                                   uint8_t *ref_mv_count,
+#endif
+#if CONFIG_EXT_INTER
+                                   int_mv *mv_list,
+#endif  // CONFIG_EXT_INTER
+                                   int_mv *nearest_mv, int_mv *near_mv) {
+#if !CONFIG_EXT_INTER
+  int_mv mv_list[MAX_MV_REF_CANDIDATES];
+#endif  // !CONFIG_EXT_INTER
+  MODE_INFO *const mi = xd->mi[0];
+  b_mode_info *bmi = mi->bmi;
+  int n;
+  int_mv zeromv;
+#if CONFIG_REF_MV
+  CANDIDATE_MV tmp_mv;
+  uint8_t idx;
+  uint8_t above_count = 0, left_count = 0;
+  MV_REFERENCE_FRAME rf[2] = { mi->mbmi.ref_frame[ref], NONE_FRAME };
+  *ref_mv_count = 0;
+#endif
+
+  assert(MAX_MV_REF_CANDIDATES == 2);
+
+#if CONFIG_GLOBAL_MOTION
+  zeromv.as_int =
+      gm_get_motion_vector(&cm->global_motion[ref], cm->allow_high_precision_mv,
+                           mi->mbmi.sb_type, mi_col, mi_row, block)
+          .as_int;
+#else
+  zeromv.as_int = 0;
+#endif
+  find_mv_refs_idx(cm, xd, mi, mi->mbmi.ref_frame[ref], mv_list, block, mi_row,
+                   mi_col, NULL, NULL, NULL, zeromv);
+
+#if CONFIG_REF_MV
+  scan_blk_mbmi(cm, xd, mi_row, mi_col, block, rf, -1, 0, ref_mv_stack,
+                ref_mv_count);
+  above_count = *ref_mv_count;
+
+  scan_blk_mbmi(cm, xd, mi_row, mi_col, block, rf, 0, -1, ref_mv_stack,
+                ref_mv_count);
+  left_count = *ref_mv_count - above_count;
+
+  if (above_count > 1 && left_count > 0) {
+    tmp_mv = ref_mv_stack[1];
+    ref_mv_stack[1] = ref_mv_stack[above_count];
+    ref_mv_stack[above_count] = tmp_mv;
+  }
+
+  for (idx = 0; idx < *ref_mv_count; ++idx)
+    clamp_mv_ref(&ref_mv_stack[idx].this_mv.as_mv, xd->n8_w << MI_SIZE_LOG2,
+                 xd->n8_h << MI_SIZE_LOG2, xd);
+
+  for (idx = 0; idx < AOMMIN(MAX_MV_REF_CANDIDATES, *ref_mv_count); ++idx)
+    mv_list[idx].as_int = ref_mv_stack[idx].this_mv.as_int;
+#endif
+
+  near_mv->as_int = 0;
+  switch (block) {
+    case 0:
+      nearest_mv->as_int = mv_list[0].as_int;
+      near_mv->as_int = mv_list[1].as_int;
+      break;
+    case 1:
+    case 2:
+      nearest_mv->as_int = bmi[0].as_mv[ref].as_int;
+      for (n = 0; n < MAX_MV_REF_CANDIDATES; ++n)
+        if (nearest_mv->as_int != mv_list[n].as_int) {
+          near_mv->as_int = mv_list[n].as_int;
+          break;
+        }
+      break;
+    case 3: {
+      int_mv candidates[2 + MAX_MV_REF_CANDIDATES];
+      candidates[0] = bmi[1].as_mv[ref];
+      candidates[1] = bmi[0].as_mv[ref];
+      candidates[2] = mv_list[0];
+      candidates[3] = mv_list[1];
+
+      nearest_mv->as_int = bmi[2].as_mv[ref].as_int;
+      for (n = 0; n < 2 + MAX_MV_REF_CANDIDATES; ++n)
+        if (nearest_mv->as_int != candidates[n].as_int) {
+          near_mv->as_int = candidates[n].as_int;
+          break;
+        }
+      break;
+    }
+    default: assert(0 && "Invalid block index.");
+  }
+}
+
+#if CONFIG_WARPED_MOTION
+void calc_projection_samples(MB_MODE_INFO *const mbmi, int x, int y,
+                             int *pts_inref) {
+  pts_inref[0] = (x * 8) + mbmi->mv[0].as_mv.col;
+  pts_inref[1] = (y * 8) + mbmi->mv[0].as_mv.row;
+}
+
+// Note: Samples returned are at 1/8-pel precision
+int findSamples(const AV1_COMMON *cm, MACROBLOCKD *xd, int mi_row, int mi_col,
+                int *pts, int *pts_inref) {
+  MB_MODE_INFO *const mbmi0 = &(xd->mi[0]->mbmi);
+  int ref_frame = mbmi0->ref_frame[0];
+  int up_available = xd->up_available;
+  int left_available = xd->left_available;
+  int i, mi_step, np = 0;
+  int global_offset_c = mi_col * MI_SIZE;
+  int global_offset_r = mi_row * MI_SIZE;
+
+  // scan the above row
+  if (up_available) {
+    for (i = 0; i < AOMMIN(xd->n8_w, cm->mi_cols - mi_col); i += mi_step) {
+      int mi_row_offset = -1;
+      int mi_col_offset = i;
+
+      MODE_INFO *mi = xd->mi[mi_col_offset + mi_row_offset * xd->mi_stride];
+      MB_MODE_INFO *mbmi = &mi->mbmi;
+
+      mi_step = AOMMIN(xd->n8_w, mi_size_wide[mbmi->sb_type]);
+
+      if (mbmi->ref_frame[0] == ref_frame && mbmi->ref_frame[1] == NONE_FRAME) {
+        int bw = block_size_wide[mbmi->sb_type];
+        int bh = block_size_high[mbmi->sb_type];
+        int cr_offset = -AOMMAX(bh, MI_SIZE) / 2 - 1;
+        int cc_offset = i * MI_SIZE + AOMMAX(bw, MI_SIZE) / 2 - 1;
+        int x = cc_offset + global_offset_c;
+        int y = cr_offset + global_offset_r;
+
+        pts[0] = (x * 8);
+        pts[1] = (y * 8);
+        calc_projection_samples(mbmi, x, y, pts_inref);
+        pts += 2;
+        pts_inref += 2;
+        np++;
+        if (np >= LEAST_SQUARES_SAMPLES_MAX) return LEAST_SQUARES_SAMPLES_MAX;
+      }
+    }
+  }
+  assert(2 * np <= SAMPLES_ARRAY_SIZE);
+
+  // scan the left column
+  if (left_available) {
+    for (i = 0; i < AOMMIN(xd->n8_h, cm->mi_rows - mi_row); i += mi_step) {
+      int mi_row_offset = i;
+      int mi_col_offset = -1;
+
+      MODE_INFO *mi = xd->mi[mi_col_offset + mi_row_offset * xd->mi_stride];
+      MB_MODE_INFO *mbmi = &mi->mbmi;
+
+      mi_step = AOMMIN(xd->n8_h, mi_size_high[mbmi->sb_type]);
+
+      if (mbmi->ref_frame[0] == ref_frame && mbmi->ref_frame[1] == NONE_FRAME) {
+        int bw = block_size_wide[mbmi->sb_type];
+        int bh = block_size_high[mbmi->sb_type];
+        int cr_offset = i * MI_SIZE + AOMMAX(bh, MI_SIZE) / 2 - 1;
+        int cc_offset = -AOMMAX(bw, MI_SIZE) / 2 - 1;
+        int x = cc_offset + global_offset_c;
+        int y = cr_offset + global_offset_r;
+
+        pts[0] = (x * 8);
+        pts[1] = (y * 8);
+        calc_projection_samples(mbmi, x, y, pts_inref);
+        pts += 2;
+        pts_inref += 2;
+        np++;
+        if (np >= LEAST_SQUARES_SAMPLES_MAX) return LEAST_SQUARES_SAMPLES_MAX;
+      }
+    }
+  }
+  assert(2 * np <= SAMPLES_ARRAY_SIZE);
+
+  if (left_available && up_available) {
+    int mi_row_offset = -1;
+    int mi_col_offset = -1;
+
+    MODE_INFO *mi = xd->mi[mi_col_offset + mi_row_offset * xd->mi_stride];
+    MB_MODE_INFO *mbmi = &mi->mbmi;
+
+    if (mbmi->ref_frame[0] == ref_frame && mbmi->ref_frame[1] == NONE_FRAME) {
+      int bw = block_size_wide[mbmi->sb_type];
+      int bh = block_size_high[mbmi->sb_type];
+      int cr_offset = -AOMMAX(bh, MI_SIZE) / 2 - 1;
+      int cc_offset = -AOMMAX(bw, MI_SIZE) / 2 - 1;
+      int x = cc_offset + global_offset_c;
+      int y = cr_offset + global_offset_r;
+
+      pts[0] = (x * 8);
+      pts[1] = (y * 8);
+      calc_projection_samples(mbmi, x, y, pts_inref);
+      np++;
+    }
+  }
+  assert(2 * np <= SAMPLES_ARRAY_SIZE);
+
+  return np;
+}
+#endif  // CONFIG_WARPED_MOTION