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, 1408 insertions, 0 deletions

diff --git a/third_party/aom/av1/common/pred_common.c b/third_party/aom/av1/common/pred_common.c
new file mode 100644
index 000000000..905dd3afe
--- /dev/null
+++ b/third_party/aom/av1/common/pred_common.c
@@ -0,0 +1,1408 @@
+/*
+ * 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/common.h"
+#include "av1/common/pred_common.h"
+#include "av1/common/reconinter.h"
+#if CONFIG_EXT_INTRA
+#include "av1/common/reconintra.h"
+#endif  // CONFIG_EXT_INTRA
+#include "av1/common/seg_common.h"
+
+// Returns a context number for the given MB prediction signal
+#if CONFIG_DUAL_FILTER
+static InterpFilter get_ref_filter_type(const MODE_INFO *mi,
+                                        const MACROBLOCKD *xd, int dir,
+                                        MV_REFERENCE_FRAME ref_frame) {
+  InterpFilter ref_type = SWITCHABLE_FILTERS;
+  const MB_MODE_INFO *ref_mbmi = &mi->mbmi;
+  int use_subpel[2] = {
+    has_subpel_mv_component(mi, xd, dir),
+    has_subpel_mv_component(mi, xd, dir + 2),
+  };
+
+  if (ref_mbmi->ref_frame[0] == ref_frame && use_subpel[0])
+    ref_type = ref_mbmi->interp_filter[(dir & 0x01)];
+  else if (ref_mbmi->ref_frame[1] == ref_frame && use_subpel[1])
+    ref_type = ref_mbmi->interp_filter[(dir & 0x01) + 2];
+
+  return ref_type;
+}
+
+int av1_get_pred_context_switchable_interp(const MACROBLOCKD *xd, int dir) {
+  const MB_MODE_INFO *const mbmi = &xd->mi[0]->mbmi;
+  const int ctx_offset =
+      (mbmi->ref_frame[1] > INTRA_FRAME) * INTER_FILTER_COMP_OFFSET;
+  MV_REFERENCE_FRAME ref_frame =
+      (dir < 2) ? mbmi->ref_frame[0] : mbmi->ref_frame[1];
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries corresponding to real macroblocks.
+  // The prediction flags in these dummy entries are initialized to 0.
+  int filter_type_ctx = ctx_offset + (dir & 0x01) * INTER_FILTER_DIR_OFFSET;
+  int left_type = SWITCHABLE_FILTERS;
+  int above_type = SWITCHABLE_FILTERS;
+
+  if (xd->left_available)
+    left_type = get_ref_filter_type(xd->mi[-1], xd, dir, ref_frame);
+
+  if (xd->up_available)
+    above_type =
+        get_ref_filter_type(xd->mi[-xd->mi_stride], xd, dir, ref_frame);
+
+  if (left_type == above_type) {
+    filter_type_ctx += left_type;
+  } else if (left_type == SWITCHABLE_FILTERS) {
+    assert(above_type != SWITCHABLE_FILTERS);
+    filter_type_ctx += above_type;
+  } else if (above_type == SWITCHABLE_FILTERS) {
+    assert(left_type != SWITCHABLE_FILTERS);
+    filter_type_ctx += left_type;
+  } else {
+    filter_type_ctx += SWITCHABLE_FILTERS;
+  }
+
+  return filter_type_ctx;
+}
+#else
+int av1_get_pred_context_switchable_interp(const MACROBLOCKD *xd) {
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries corresponding to real macroblocks.
+  // The prediction flags in these dummy entries are initialized to 0.
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int left_type = xd->left_available && is_inter_block(left_mbmi)
+                            ? left_mbmi->interp_filter
+                            : SWITCHABLE_FILTERS;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const int above_type = xd->up_available && is_inter_block(above_mbmi)
+                             ? above_mbmi->interp_filter
+                             : SWITCHABLE_FILTERS;
+
+  if (left_type == above_type) {
+    return left_type;
+  } else if (left_type == SWITCHABLE_FILTERS) {
+    assert(above_type != SWITCHABLE_FILTERS);
+    return above_type;
+  } else if (above_type == SWITCHABLE_FILTERS) {
+    assert(left_type != SWITCHABLE_FILTERS);
+    return left_type;
+  } else {
+    return SWITCHABLE_FILTERS;
+  }
+}
+#endif
+
+#if CONFIG_EXT_INTRA
+#if CONFIG_INTRA_INTERP
+// Obtain the reference filter type from the above/left neighbor blocks.
+static INTRA_FILTER get_ref_intra_filter(const MB_MODE_INFO *ref_mbmi) {
+  INTRA_FILTER ref_type = INTRA_FILTERS;
+
+  if (ref_mbmi->sb_type >= BLOCK_8X8) {
+    const PREDICTION_MODE mode = ref_mbmi->mode;
+    if (is_inter_block(ref_mbmi)) {
+#if CONFIG_DUAL_FILTER
+      switch (ref_mbmi->interp_filter[0]) {
+#else
+      switch (ref_mbmi->interp_filter) {
+#endif
+        case EIGHTTAP_REGULAR: ref_type = INTRA_FILTER_8TAP; break;
+        case EIGHTTAP_SMOOTH: ref_type = INTRA_FILTER_8TAP_SMOOTH; break;
+        case MULTITAP_SHARP: ref_type = INTRA_FILTER_8TAP_SHARP; break;
+        case BILINEAR: ref_type = INTRA_FILTERS; break;
+        default: break;
+      }
+    } else {
+      if (av1_is_directional_mode(mode, ref_mbmi->sb_type)) {
+        const int p_angle =
+            mode_to_angle_map[mode] + ref_mbmi->angle_delta[0] * ANGLE_STEP;
+        if (av1_is_intra_filter_switchable(p_angle)) {
+          ref_type = ref_mbmi->intra_filter;
+        }
+      }
+    }
+  }
+  return ref_type;
+}
+
+int av1_get_pred_context_intra_interp(const MACROBLOCKD *xd) {
+  int left_type = INTRA_FILTERS, above_type = INTRA_FILTERS;
+
+  if (xd->left_available) left_type = get_ref_intra_filter(xd->left_mbmi);
+
+  if (xd->up_available) above_type = get_ref_intra_filter(xd->above_mbmi);
+
+  if (left_type == above_type)
+    return left_type;
+  else if (left_type == INTRA_FILTERS && above_type != INTRA_FILTERS)
+    return above_type;
+  else if (left_type != INTRA_FILTERS && above_type == INTRA_FILTERS)
+    return left_type;
+  else
+    return INTRA_FILTERS;
+}
+#endif  // CONFIG_INTRA_INTERP
+#endif  // CONFIG_EXT_INTRA
+
+// The mode info data structure has a one element border above and to the
+// left of the entries corresponding to real macroblocks.
+// The prediction flags in these dummy entries are initialized to 0.
+// 0 - inter/inter, inter/--, --/inter, --/--
+// 1 - intra/inter, inter/intra
+// 2 - intra/--, --/intra
+// 3 - intra/intra
+int av1_get_intra_inter_context(const MACROBLOCKD *xd) {
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int has_above = xd->up_available;
+  const int has_left = xd->left_available;
+
+  if (has_above && has_left) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+    return left_intra && above_intra ? 3 : left_intra || above_intra;
+  } else if (has_above || has_left) {  // one edge available
+    return 2 * !is_inter_block(has_above ? above_mbmi : left_mbmi);
+  } else {
+    return 0;
+  }
+}
+
+#if CONFIG_EXT_INTER && CONFIG_COMPOUND_SINGLEREF
+// The compound/single mode info data structure has one element border above and
+// to the left of the entries corresponding to real macroblocks.
+// The prediction flags in these dummy entries are initialized to 0.
+// 0 - single/single
+// 1 - single/--, --/single, --/--
+// 2 - single/comp, comp/single
+// 3 - comp/comp, comp/--, --/comp
+int av1_get_inter_mode_context(const MACROBLOCKD *xd) {
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int has_above = xd->up_available;
+  const int has_left = xd->left_available;
+
+  if (has_above && has_left) {  // both edges available (0/2/3)
+    const int above_inter_comp_mode = is_inter_compound_mode(above_mbmi->mode);
+    const int left_inter_comp_mode = is_inter_compound_mode(left_mbmi->mode);
+    return (above_inter_comp_mode && left_inter_comp_mode)
+               ? 3
+               : (above_inter_comp_mode || left_inter_comp_mode) * 2;
+  } else if (has_above || has_left) {  // one edge available (1/3)
+    const MB_MODE_INFO *const edge_mbmi = has_above ? above_mbmi : left_mbmi;
+    return is_inter_compound_mode(edge_mbmi->mode) ? 3 : 1;
+  } else {  // no edge available (1)
+    return 1;
+  }
+}
+#endif  // CONFIG_EXT_INTER && CONFIG_COMPOUND_SINGLEREF
+
+#if CONFIG_EXT_REFS
+#define CHECK_BACKWARD_REFS(ref_frame) \
+  (((ref_frame) >= BWDREF_FRAME) && ((ref_frame) <= ALTREF_FRAME))
+#define IS_BACKWARD_REF_FRAME(ref_frame) CHECK_BACKWARD_REFS(ref_frame)
+#else
+#define IS_BACKWARD_REF_FRAME(ref_frame) ((ref_frame) == cm->comp_fixed_ref)
+#endif  // CONFIG_EXT_REFS
+
+int av1_get_reference_mode_context(const AV1_COMMON *cm,
+                                   const MACROBLOCKD *xd) {
+  int ctx;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int has_above = xd->up_available;
+  const int has_left = xd->left_available;
+
+#if CONFIG_EXT_REFS
+  (void)cm;
+#endif  // CONFIG_EXT_REFS
+
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries corresponding to real macroblocks.
+  // The prediction flags in these dummy entries are initialized to 0.
+  if (has_above && has_left) {  // both edges available
+    if (!has_second_ref(above_mbmi) && !has_second_ref(left_mbmi))
+      // neither edge uses comp pred (0/1)
+      ctx = IS_BACKWARD_REF_FRAME(above_mbmi->ref_frame[0]) ^
+            IS_BACKWARD_REF_FRAME(left_mbmi->ref_frame[0]);
+    else if (!has_second_ref(above_mbmi))
+      // one of two edges uses comp pred (2/3)
+      ctx = 2 + (IS_BACKWARD_REF_FRAME(above_mbmi->ref_frame[0]) ||
+                 !is_inter_block(above_mbmi));
+    else if (!has_second_ref(left_mbmi))
+      // one of two edges uses comp pred (2/3)
+      ctx = 2 + (IS_BACKWARD_REF_FRAME(left_mbmi->ref_frame[0]) ||
+                 !is_inter_block(left_mbmi));
+    else  // both edges use comp pred (4)
+      ctx = 4;
+  } else if (has_above || has_left) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;
+
+    if (!has_second_ref(edge_mbmi))
+      // edge does not use comp pred (0/1)
+      ctx = IS_BACKWARD_REF_FRAME(edge_mbmi->ref_frame[0]);
+    else
+      // edge uses comp pred (3)
+      ctx = 3;
+  } else {  // no edges available (1)
+    ctx = 1;
+  }
+  assert(ctx >= 0 && ctx < COMP_INTER_CONTEXTS);
+  return ctx;
+}
+
+#if CONFIG_EXT_REFS
+
+// TODO(zoeliu): Future work will be conducted to optimize the context design
+//               for the coding of the reference frames.
+
+#define CHECK_LAST_OR_LAST2(ref_frame) \
+  ((ref_frame == LAST_FRAME) || (ref_frame == LAST2_FRAME))
+
+#define CHECK_GOLDEN_OR_LAST3(ref_frame) \
+  ((ref_frame == GOLDEN_FRAME) || (ref_frame == LAST3_FRAME))
+
+// Returns a context number for the given MB prediction signal
+// Signal the first reference frame for a compound mode be either
+// GOLDEN/LAST3, or LAST/LAST2.
+//
+// NOTE(zoeliu): The probability of ref_frame[0] is either
+//               GOLDEN_FRAME or LAST3_FRAME.
+#if CONFIG_LOWDELAY_COMPOUND
+int av1_get_pred_context_comp_ref_p(UNUSED const AV1_COMMON *cm,
+                                    const MACROBLOCKD *xd) {
+#else
+int av1_get_pred_context_comp_ref_p(const AV1_COMMON *cm,
+                                    const MACROBLOCKD *xd) {
+#endif
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int above_in_image = xd->up_available;
+  const int left_in_image = xd->left_available;
+
+// Note:
+// The mode info data structure has a one element border above and to the
+// left of the entries correpsonding to real macroblocks.
+// The prediction flags in these dummy entries are initialised to 0.
+#if CONFIG_LOWDELAY_COMPOUND  // No change to bitstream
+  // Code seems to assume that signbias of cm->comp_bwd_ref[0] is always 1
+  const int bwd_ref_sign_idx = 1;
+#else
+  const int bwd_ref_sign_idx = cm->ref_frame_sign_bias[cm->comp_bwd_ref[0]];
+#endif
+  const int fwd_ref_sign_idx = !bwd_ref_sign_idx;
+
+  if (above_in_image && left_in_image) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra (2)
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+
+      if (!has_second_ref(edge_mbmi))  // single pred (1/3)
+        pred_context =
+            1 + 2 * (!CHECK_GOLDEN_OR_LAST3(edge_mbmi->ref_frame[0]));
+      else  // comp pred (1/3)
+        pred_context = 1 +
+                       2 * (!CHECK_GOLDEN_OR_LAST3(
+                               edge_mbmi->ref_frame[fwd_ref_sign_idx]));
+    } else {  // inter/inter
+      const int l_sg = !has_second_ref(left_mbmi);
+      const int a_sg = !has_second_ref(above_mbmi);
+      const MV_REFERENCE_FRAME frfa =
+          a_sg ? above_mbmi->ref_frame[0]
+               : above_mbmi->ref_frame[fwd_ref_sign_idx];
+      const MV_REFERENCE_FRAME frfl =
+          l_sg ? left_mbmi->ref_frame[0]
+               : left_mbmi->ref_frame[fwd_ref_sign_idx];
+
+      if (frfa == frfl && CHECK_GOLDEN_OR_LAST3(frfa)) {
+        pred_context = 0;
+      } else if (l_sg && a_sg) {  // single/single
+        if ((CHECK_BACKWARD_REFS(frfa) && CHECK_LAST_OR_LAST2(frfl)) ||
+            (CHECK_BACKWARD_REFS(frfl) && CHECK_LAST_OR_LAST2(frfa))) {
+          pred_context = 4;
+        } else if (CHECK_GOLDEN_OR_LAST3(frfa) || CHECK_GOLDEN_OR_LAST3(frfl)) {
+          pred_context = 1;
+        } else {
+          pred_context = 3;
+        }
+      } else if (l_sg || a_sg) {  // single/comp
+        const MV_REFERENCE_FRAME frfc = l_sg ? frfa : frfl;
+        const MV_REFERENCE_FRAME rfs = a_sg ? frfa : frfl;
+
+        if (CHECK_GOLDEN_OR_LAST3(frfc) && !CHECK_GOLDEN_OR_LAST3(rfs))
+          pred_context = 1;
+        else if (CHECK_GOLDEN_OR_LAST3(rfs) && !CHECK_GOLDEN_OR_LAST3(frfc))
+          pred_context = 2;
+        else
+          pred_context = 4;
+      } else {  // comp/comp
+        if ((CHECK_LAST_OR_LAST2(frfa) && CHECK_LAST_OR_LAST2(frfl))) {
+          pred_context = 4;
+        } else {
+          // NOTE(zoeliu): Following assert may be removed once confirmed.
+          assert(CHECK_GOLDEN_OR_LAST3(frfa) || CHECK_GOLDEN_OR_LAST3(frfl));
+          pred_context = 2;
+        }
+      }
+    }
+  } else if (above_in_image || left_in_image) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;
+
+    if (!is_inter_block(edge_mbmi)) {
+      pred_context = 2;
+    } else {
+      if (has_second_ref(edge_mbmi))
+        pred_context =
+            4 *
+            (!CHECK_GOLDEN_OR_LAST3(edge_mbmi->ref_frame[fwd_ref_sign_idx]));
+      else
+        pred_context = 3 * (!CHECK_GOLDEN_OR_LAST3(edge_mbmi->ref_frame[0]));
+    }
+  } else {  // no edges available (2)
+    pred_context = 2;
+  }
+
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+
+  return pred_context;
+}
+
+// Returns a context number for the given MB prediction signal
+// Signal the first reference frame for a compound mode be LAST,
+// conditioning on that it is known either LAST/LAST2.
+//
+// NOTE(zoeliu): The probability of ref_frame[0] is LAST_FRAME,
+// conditioning on it is either LAST_FRAME or LAST2_FRAME.
+#if CONFIG_LOWDELAY_COMPOUND
+int av1_get_pred_context_comp_ref_p1(UNUSED const AV1_COMMON *cm,
+                                     const MACROBLOCKD *xd) {
+#else
+int av1_get_pred_context_comp_ref_p1(const AV1_COMMON *cm,
+                                     const MACROBLOCKD *xd) {
+#endif
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int above_in_image = xd->up_available;
+  const int left_in_image = xd->left_available;
+
+// Note:
+// The mode info data structure has a one element border above and to the
+// left of the entries correpsonding to real macroblocks.
+// The prediction flags in these dummy entries are initialised to 0.
+#if CONFIG_LOWDELAY_COMPOUND  // No change to bitstream
+  // Code seems to assume that signbias of cm->comp_bwd_ref[0] is always 1
+  const int bwd_ref_sign_idx = 1;
+#else
+  const int bwd_ref_sign_idx = cm->ref_frame_sign_bias[cm->comp_bwd_ref[0]];
+#endif
+  const int fwd_ref_sign_idx = !bwd_ref_sign_idx;
+
+  if (above_in_image && left_in_image) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra (2)
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+
+      if (!has_second_ref(edge_mbmi))  // single pred (1/3)
+        pred_context = 1 + 2 * (edge_mbmi->ref_frame[0] != LAST_FRAME);
+      else  // comp pred (1/3)
+        pred_context =
+            1 + 2 * (edge_mbmi->ref_frame[fwd_ref_sign_idx] != LAST_FRAME);
+    } else {  // inter/inter
+      const int l_sg = !has_second_ref(left_mbmi);
+      const int a_sg = !has_second_ref(above_mbmi);
+      const MV_REFERENCE_FRAME frfa =
+          a_sg ? above_mbmi->ref_frame[0]
+               : above_mbmi->ref_frame[fwd_ref_sign_idx];
+      const MV_REFERENCE_FRAME frfl =
+          l_sg ? left_mbmi->ref_frame[0]
+               : left_mbmi->ref_frame[fwd_ref_sign_idx];
+
+      if (frfa == frfl && frfa == LAST_FRAME)
+        pred_context = 0;
+      else if (l_sg && a_sg) {  // single/single
+        if (frfa == LAST_FRAME || frfl == LAST_FRAME)
+          pred_context = 1;
+        else if (CHECK_GOLDEN_OR_LAST3(frfa) || CHECK_GOLDEN_OR_LAST3(frfl))
+          pred_context = 2 + (frfa != frfl);
+        else if (frfa == frfl ||
+                 (CHECK_BACKWARD_REFS(frfa) && CHECK_BACKWARD_REFS(frfl)))
+          pred_context = 3;
+        else
+          pred_context = 4;
+      } else if (l_sg || a_sg) {  // single/comp
+        const MV_REFERENCE_FRAME frfc = l_sg ? frfa : frfl;
+        const MV_REFERENCE_FRAME rfs = a_sg ? frfa : frfl;
+
+        if (frfc == LAST_FRAME && rfs != LAST_FRAME)
+          pred_context = 1;
+        else if (rfs == LAST_FRAME && frfc != LAST_FRAME)
+          pred_context = 2;
+        else
+          pred_context =
+              3 + (frfc == LAST2_FRAME || CHECK_GOLDEN_OR_LAST3(rfs));
+      } else {  // comp/comp
+        if (frfa == LAST_FRAME || frfl == LAST_FRAME)
+          pred_context = 2;
+        else
+          pred_context =
+              3 + (CHECK_GOLDEN_OR_LAST3(frfa) || CHECK_GOLDEN_OR_LAST3(frfl));
+      }
+    }
+  } else if (above_in_image || left_in_image) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;
+
+    if (!is_inter_block(edge_mbmi)) {
+      pred_context = 2;
+    } else {
+      if (has_second_ref(edge_mbmi)) {
+        pred_context =
+            4 * (edge_mbmi->ref_frame[fwd_ref_sign_idx] != LAST_FRAME);
+      } else {
+        if (edge_mbmi->ref_frame[0] == LAST_FRAME)
+          pred_context = 0;
+        else
+          pred_context = 2 + CHECK_GOLDEN_OR_LAST3(edge_mbmi->ref_frame[0]);
+      }
+    }
+  } else {  // no edges available (2)
+    pred_context = 2;
+  }
+
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+
+  return pred_context;
+}
+
+// Returns a context number for the given MB prediction signal
+// Signal the first reference frame for a compound mode be GOLDEN,
+// conditioning on that it is known either GOLDEN or LAST3.
+//
+// NOTE(zoeliu): The probability of ref_frame[0] is GOLDEN_FRAME,
+// conditioning on it is either GOLDEN or LAST3.
+#if CONFIG_LOWDELAY_COMPOUND
+int av1_get_pred_context_comp_ref_p2(UNUSED const AV1_COMMON *cm,
+                                     const MACROBLOCKD *xd) {
+#else
+int av1_get_pred_context_comp_ref_p2(const AV1_COMMON *cm,
+                                     const MACROBLOCKD *xd) {
+#endif
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int above_in_image = xd->up_available;
+  const int left_in_image = xd->left_available;
+
+// Note:
+// The mode info data structure has a one element border above and to the
+// left of the entries correpsonding to real macroblocks.
+// The prediction flags in these dummy entries are initialised to 0.
+#if CONFIG_LOWDELAY_COMPOUND  // No change to bitstream
+  // Code seems to assume that signbias of cm->comp_bwd_ref[0] is always 1
+  const int bwd_ref_sign_idx = 1;
+#else
+  const int bwd_ref_sign_idx = cm->ref_frame_sign_bias[cm->comp_bwd_ref[0]];
+#endif
+  const int fwd_ref_sign_idx = !bwd_ref_sign_idx;
+
+  if (above_in_image && left_in_image) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra (2)
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+
+      if (!has_second_ref(edge_mbmi))  // single pred (1/3)
+        pred_context = 1 + 2 * (edge_mbmi->ref_frame[0] != GOLDEN_FRAME);
+      else  // comp pred (1/3)
+        pred_context =
+            1 + 2 * (edge_mbmi->ref_frame[fwd_ref_sign_idx] != GOLDEN_FRAME);
+    } else {  // inter/inter
+      const int l_sg = !has_second_ref(left_mbmi);
+      const int a_sg = !has_second_ref(above_mbmi);
+      const MV_REFERENCE_FRAME frfa =
+          a_sg ? above_mbmi->ref_frame[0]
+               : above_mbmi->ref_frame[fwd_ref_sign_idx];
+      const MV_REFERENCE_FRAME frfl =
+          l_sg ? left_mbmi->ref_frame[0]
+               : left_mbmi->ref_frame[fwd_ref_sign_idx];
+
+      if (frfa == frfl && frfa == GOLDEN_FRAME)
+        pred_context = 0;
+      else if (l_sg && a_sg) {  // single/single
+        if (frfa == GOLDEN_FRAME || frfl == GOLDEN_FRAME)
+          pred_context = 1;
+        else if (CHECK_LAST_OR_LAST2(frfa) || CHECK_LAST_OR_LAST2(frfl))
+          pred_context = 2 + (frfa != frfl);
+        else if (frfa == frfl ||
+                 (CHECK_BACKWARD_REFS(frfa) && CHECK_BACKWARD_REFS(frfl)))
+          pred_context = 3;
+        else
+          pred_context = 4;
+      } else if (l_sg || a_sg) {  // single/comp
+        const MV_REFERENCE_FRAME frfc = l_sg ? frfa : frfl;
+        const MV_REFERENCE_FRAME rfs = a_sg ? frfa : frfl;
+
+        if (frfc == GOLDEN_FRAME && rfs != GOLDEN_FRAME)
+          pred_context = 1;
+        else if (rfs == GOLDEN_FRAME && frfc != GOLDEN_FRAME)
+          pred_context = 2;
+        else
+          pred_context = 3 + (frfc == LAST3_FRAME || CHECK_LAST_OR_LAST2(rfs));
+      } else {  // comp/comp
+        if (frfa == GOLDEN_FRAME || frfl == GOLDEN_FRAME)
+          pred_context = 2;
+        else
+          pred_context =
+              3 + (CHECK_LAST_OR_LAST2(frfa) || CHECK_LAST_OR_LAST2(frfl));
+      }
+    }
+  } else if (above_in_image || left_in_image) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;
+
+    if (!is_inter_block(edge_mbmi)) {
+      pred_context = 2;
+    } else {
+      if (has_second_ref(edge_mbmi)) {
+        pred_context =
+            4 * (edge_mbmi->ref_frame[fwd_ref_sign_idx] != GOLDEN_FRAME);
+      } else {
+        if (edge_mbmi->ref_frame[0] == GOLDEN_FRAME)
+          pred_context = 0;
+        else
+          pred_context = 2 + CHECK_LAST_OR_LAST2(edge_mbmi->ref_frame[0]);
+      }
+    }
+  } else {  // no edges available (2)
+    pred_context = 2;
+  }
+
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+
+  return pred_context;
+}
+
+// Returns a context number for the given MB prediction signal
+#if CONFIG_LOWDELAY_COMPOUND
+int av1_get_pred_context_comp_bwdref_p(UNUSED const AV1_COMMON *cm,
+                                       const MACROBLOCKD *xd) {
+#else
+int av1_get_pred_context_comp_bwdref_p(const AV1_COMMON *cm,
+                                       const MACROBLOCKD *xd) {
+#endif
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int above_in_image = xd->up_available;
+  const int left_in_image = xd->left_available;
+
+// Note:
+// The mode info data structure has a one element border above and to the
+// left of the entries corresponding to real macroblocks.
+// The prediction flags in these dummy entries are initialized to 0.
+#if CONFIG_LOWDELAY_COMPOUND  // No change to bitstream
+  // Code seems to assume that signbias of cm->comp_bwd_ref[0] is always 1
+  const int bwd_ref_sign_idx = 1;
+#else
+  const int bwd_ref_sign_idx = cm->ref_frame_sign_bias[cm->comp_bwd_ref[0]];
+#endif
+  const int fwd_ref_sign_idx = !bwd_ref_sign_idx;
+
+  if (above_in_image && left_in_image) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra (2)
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+
+      if (!has_second_ref(edge_mbmi))  // single pred (1/3)
+        pred_context = 1 + 2 * (edge_mbmi->ref_frame[0] != cm->comp_bwd_ref[1]);
+      else  // comp pred (1/3)
+        pred_context =
+            1 +
+            2 * (edge_mbmi->ref_frame[bwd_ref_sign_idx] != cm->comp_bwd_ref[1]);
+    } else {  // inter/inter
+      const int l_comp = has_second_ref(left_mbmi);
+      const int a_comp = has_second_ref(above_mbmi);
+
+      const MV_REFERENCE_FRAME l_brf =
+          l_comp ? left_mbmi->ref_frame[bwd_ref_sign_idx] : NONE_FRAME;
+      const MV_REFERENCE_FRAME a_brf =
+          a_comp ? above_mbmi->ref_frame[bwd_ref_sign_idx] : NONE_FRAME;
+
+      const MV_REFERENCE_FRAME l_frf =
+          !l_comp ? left_mbmi->ref_frame[0]
+                  : left_mbmi->ref_frame[fwd_ref_sign_idx];
+      const MV_REFERENCE_FRAME a_frf =
+          !a_comp ? above_mbmi->ref_frame[0]
+                  : above_mbmi->ref_frame[fwd_ref_sign_idx];
+
+      if (l_comp && a_comp) {  // comp/comp
+        if (l_brf == a_brf && l_brf == cm->comp_bwd_ref[1]) {
+          pred_context = 0;
+        } else if (l_brf == cm->comp_bwd_ref[1] ||
+                   a_brf == cm->comp_bwd_ref[1]) {
+          pred_context = 1;
+        } else {
+          // NOTE: Backward ref should be either BWDREF or ALTREF.
+          assert(l_brf == a_brf && l_brf != cm->comp_bwd_ref[1]);
+          pred_context = 3;
+        }
+      } else if (!l_comp && !a_comp) {  // single/single
+        if (l_frf == a_frf && l_frf == cm->comp_bwd_ref[1]) {
+          pred_context = 0;
+        } else if (l_frf == cm->comp_bwd_ref[1] ||
+                   a_frf == cm->comp_bwd_ref[1]) {
+          pred_context = 1;
+        } else if (l_frf == a_frf) {
+          pred_context = 3;
+        } else {
+          assert(l_frf != a_frf && l_frf != cm->comp_bwd_ref[1] &&
+                 a_frf != cm->comp_bwd_ref[1]);
+          pred_context = 4;
+        }
+      } else {  // comp/single
+        assert((l_comp && !a_comp) || (!l_comp && a_comp));
+
+        if ((l_comp && l_brf == cm->comp_bwd_ref[1] &&
+             a_frf == cm->comp_bwd_ref[1]) ||
+            (a_comp && a_brf == cm->comp_bwd_ref[1] &&
+             l_frf == cm->comp_bwd_ref[1])) {
+          pred_context = 1;
+        } else if ((l_comp && l_brf == cm->comp_bwd_ref[1]) ||
+                   (a_comp && a_brf == cm->comp_bwd_ref[1]) ||
+                   (!l_comp && l_frf == cm->comp_bwd_ref[1]) ||
+                   (!a_comp && a_frf == cm->comp_bwd_ref[1])) {
+          pred_context = 2;
+        } else {
+          pred_context = 4;
+        }
+      }
+    }
+  } else if (above_in_image || left_in_image) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;
+
+    if (!is_inter_block(edge_mbmi)) {
+      pred_context = 2;
+    } else {
+      if (has_second_ref(edge_mbmi)) {
+        pred_context =
+            4 * (edge_mbmi->ref_frame[bwd_ref_sign_idx] != cm->comp_bwd_ref[1]);
+      } else {
+        pred_context = 3 * (edge_mbmi->ref_frame[0] != cm->comp_bwd_ref[1]);
+      }
+    }
+  } else {  // no edges available (2)
+    pred_context = 2;
+  }
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+
+  return pred_context;
+}
+
+#else  // CONFIG_EXT_REFS
+
+// Returns a context number for the given MB prediction signal
+int av1_get_pred_context_comp_ref_p(const AV1_COMMON *cm,
+                                    const MACROBLOCKD *xd) {
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int above_in_image = xd->up_available;
+  const int left_in_image = xd->left_available;
+
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries corresponding to real macroblocks.
+  // The prediction flags in these dummy entries are initialized to 0.
+  const int fix_ref_idx = cm->ref_frame_sign_bias[cm->comp_fixed_ref];
+  const int var_ref_idx = !fix_ref_idx;
+
+  if (above_in_image && left_in_image) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra (2)
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+
+      if (!has_second_ref(edge_mbmi))  // single pred (1/3)
+        pred_context = 1 + 2 * (edge_mbmi->ref_frame[0] != cm->comp_var_ref[1]);
+      else  // comp pred (1/3)
+        pred_context =
+            1 + 2 * (edge_mbmi->ref_frame[var_ref_idx] != cm->comp_var_ref[1]);
+    } else {  // inter/inter
+      const int l_sg = !has_second_ref(left_mbmi);
+      const int a_sg = !has_second_ref(above_mbmi);
+      const MV_REFERENCE_FRAME vrfa =
+          a_sg ? above_mbmi->ref_frame[0] : above_mbmi->ref_frame[var_ref_idx];
+      const MV_REFERENCE_FRAME vrfl =
+          l_sg ? left_mbmi->ref_frame[0] : left_mbmi->ref_frame[var_ref_idx];
+
+      if (vrfa == vrfl && cm->comp_var_ref[1] == vrfa) {
+        pred_context = 0;
+      } else if (l_sg && a_sg) {  // single/single
+        if ((vrfa == cm->comp_fixed_ref && vrfl == cm->comp_var_ref[0]) ||
+            (vrfl == cm->comp_fixed_ref && vrfa == cm->comp_var_ref[0]))
+          pred_context = 4;
+        else if (vrfa == vrfl)
+          pred_context = 3;
+        else
+          pred_context = 1;
+      } else if (l_sg || a_sg) {  // single/comp
+        const MV_REFERENCE_FRAME vrfc = l_sg ? vrfa : vrfl;
+        const MV_REFERENCE_FRAME rfs = a_sg ? vrfa : vrfl;
+        if (vrfc == cm->comp_var_ref[1] && rfs != cm->comp_var_ref[1])
+          pred_context = 1;
+        else if (rfs == cm->comp_var_ref[1] && vrfc != cm->comp_var_ref[1])
+          pred_context = 2;
+        else
+          pred_context = 4;
+      } else if (vrfa == vrfl) {  // comp/comp
+        pred_context = 4;
+      } else {
+        pred_context = 2;
+      }
+    }
+  } else if (above_in_image || left_in_image) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = above_in_image ? above_mbmi : left_mbmi;
+
+    if (!is_inter_block(edge_mbmi)) {
+      pred_context = 2;
+    } else {
+      if (has_second_ref(edge_mbmi))
+        pred_context =
+            4 * (edge_mbmi->ref_frame[var_ref_idx] != cm->comp_var_ref[1]);
+      else
+        pred_context = 3 * (edge_mbmi->ref_frame[0] != cm->comp_var_ref[1]);
+    }
+  } else {  // no edges available (2)
+    pred_context = 2;
+  }
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+
+  return pred_context;
+}
+
+#endif  // CONFIG_EXT_REFS
+
+#if CONFIG_EXT_REFS
+
+// For the bit to signal whether the single reference is a ALTREF_FRAME
+// or a BWDREF_FRAME.
+//
+// NOTE(zoeliu): The probability of ref_frame[0] is ALTREF/BWDREF.
+int av1_get_pred_context_single_ref_p1(const MACROBLOCKD *xd) {
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int has_above = xd->up_available;
+  const int has_left = xd->left_available;
+
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries correpsonding to real macroblocks.
+  // The prediction flags in these dummy entries are initialised to 0.
+  if (has_above && has_left) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter or inter/intra
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+
+      if (!has_second_ref(edge_mbmi))  // single
+        pred_context = 4 * (!CHECK_BACKWARD_REFS(edge_mbmi->ref_frame[0]));
+      else  // comp
+        pred_context = 2;
+    } else {  // inter/inter
+      const int above_has_second = has_second_ref(above_mbmi);
+      const int left_has_second = has_second_ref(left_mbmi);
+
+      const MV_REFERENCE_FRAME above0 = above_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME left0 = left_mbmi->ref_frame[0];
+
+      if (above_has_second && left_has_second) {  // comp/comp
+        pred_context = 2;
+      } else if (above_has_second || left_has_second) {  // single/comp
+        const MV_REFERENCE_FRAME rfs = !above_has_second ? above0 : left0;
+
+        pred_context = (!CHECK_BACKWARD_REFS(rfs)) ? 4 : 1;
+      } else {  // single/single
+        pred_context = 2 * (!CHECK_BACKWARD_REFS(above0)) +
+                       2 * (!CHECK_BACKWARD_REFS(left0));
+      }
+    }
+  } else if (has_above || has_left) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;
+    if (!is_inter_block(edge_mbmi)) {  // intra
+      pred_context = 2;
+    } else {                           // inter
+      if (!has_second_ref(edge_mbmi))  // single
+        pred_context = 4 * (!CHECK_BACKWARD_REFS(edge_mbmi->ref_frame[0]));
+      else  // comp
+        pred_context = 2;
+    }
+  } else {  // no edges available
+    pred_context = 2;
+  }
+
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+  return pred_context;
+}
+
+// For the bit to signal whether the single reference is ALTREF_FRAME or
+// BWDREF_FRAME, knowing that it shall be either of these 2 choices.
+//
+// NOTE(zoeliu): The probability of ref_frame[0] is ALTREF_FRAME, conditioning
+// on it is either ALTREF_FRAME/BWDREF_FRAME.
+int av1_get_pred_context_single_ref_p2(const MACROBLOCKD *xd) {
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int has_above = xd->up_available;
+  const int has_left = xd->left_available;
+
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries correpsonding to real macroblocks.
+  // The prediction flags in these dummy entries are initialised to 0.
+  if (has_above && has_left) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter or inter/intra
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+      if (!has_second_ref(edge_mbmi)) {  // single
+        if (!CHECK_BACKWARD_REFS(edge_mbmi->ref_frame[0]))
+          pred_context = 3;
+        else
+          pred_context = 4 * (edge_mbmi->ref_frame[0] == BWDREF_FRAME);
+      } else {  // comp
+        pred_context = 1 +
+                       2 * (edge_mbmi->ref_frame[0] == BWDREF_FRAME ||
+                            edge_mbmi->ref_frame[1] == BWDREF_FRAME);
+      }
+    } else {  // inter/inter
+      const int above_has_second = has_second_ref(above_mbmi);
+      const int left_has_second = has_second_ref(left_mbmi);
+      const MV_REFERENCE_FRAME above0 = above_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME above1 = above_mbmi->ref_frame[1];
+      const MV_REFERENCE_FRAME left0 = left_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME left1 = left_mbmi->ref_frame[1];
+
+      if (above_has_second && left_has_second) {  // comp/comp
+        if (above0 == left0 && above1 == left1)
+          pred_context =
+              3 * (above0 == BWDREF_FRAME || above1 == BWDREF_FRAME ||
+                   left0 == BWDREF_FRAME || left1 == BWDREF_FRAME);
+        else
+          pred_context = 2;
+      } else if (above_has_second || left_has_second) {  // single/comp
+        const MV_REFERENCE_FRAME rfs = !above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf1 = above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf2 = above_has_second ? above1 : left1;
+
+        if (rfs == BWDREF_FRAME)
+          pred_context = 3 + (crf1 == BWDREF_FRAME || crf2 == BWDREF_FRAME);
+        else if (rfs == ALTREF_FRAME)
+          pred_context = (crf1 == BWDREF_FRAME || crf2 == BWDREF_FRAME);
+        else
+          pred_context = 1 + 2 * (crf1 == BWDREF_FRAME || crf2 == BWDREF_FRAME);
+      } else {  // single/single
+        if (!CHECK_BACKWARD_REFS(above0) && !CHECK_BACKWARD_REFS(left0)) {
+          pred_context = 2 + (above0 == left0);
+        } else if (!CHECK_BACKWARD_REFS(above0) ||
+                   !CHECK_BACKWARD_REFS(left0)) {
+          const MV_REFERENCE_FRAME edge0 =
+              !CHECK_BACKWARD_REFS(above0) ? left0 : above0;
+          pred_context = 4 * (edge0 == BWDREF_FRAME);
+        } else {
+          pred_context =
+              2 * (above0 == BWDREF_FRAME) + 2 * (left0 == BWDREF_FRAME);
+        }
+      }
+    }
+  } else if (has_above || has_left) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;
+
+    if (!is_inter_block(edge_mbmi) ||
+        (!CHECK_BACKWARD_REFS(edge_mbmi->ref_frame[0]) &&
+         !has_second_ref(edge_mbmi)))
+      pred_context = 2;
+    else if (!has_second_ref(edge_mbmi))  // single
+      pred_context = 4 * (edge_mbmi->ref_frame[0] == BWDREF_FRAME);
+    else  // comp
+      pred_context = 3 * (edge_mbmi->ref_frame[0] == BWDREF_FRAME ||
+                          edge_mbmi->ref_frame[1] == BWDREF_FRAME);
+  } else {  // no edges available (2)
+    pred_context = 2;
+  }
+
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+  return pred_context;
+}
+
+// For the bit to signal whether the single reference is LAST3/GOLDEN or
+// LAST2/LAST, knowing that it shall be either of these 2 choices.
+//
+// NOTE(zoeliu): The probability of ref_frame[0] is LAST3/GOLDEN, conditioning
+// on it is either LAST3/GOLDEN/LAST2/LAST.
+int av1_get_pred_context_single_ref_p3(const MACROBLOCKD *xd) {
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int has_above = xd->up_available;
+  const int has_left = xd->left_available;
+
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries correpsonding to real macroblocks.
+  // The prediction flags in these dummy entries are initialised to 0.
+  if (has_above && has_left) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter or inter/intra
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+      if (!has_second_ref(edge_mbmi)) {  // single
+        if (CHECK_BACKWARD_REFS(edge_mbmi->ref_frame[0]))
+          pred_context = 3;
+        else
+          pred_context = 4 * CHECK_LAST_OR_LAST2(edge_mbmi->ref_frame[0]);
+      } else {  // comp
+        pred_context = 1 +
+                       2 * (CHECK_LAST_OR_LAST2(edge_mbmi->ref_frame[0]) ||
+                            CHECK_LAST_OR_LAST2(edge_mbmi->ref_frame[1]));
+      }
+    } else {  // inter/inter
+      const int above_has_second = has_second_ref(above_mbmi);
+      const int left_has_second = has_second_ref(left_mbmi);
+      const MV_REFERENCE_FRAME above0 = above_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME above1 = above_mbmi->ref_frame[1];
+      const MV_REFERENCE_FRAME left0 = left_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME left1 = left_mbmi->ref_frame[1];
+
+      if (above_has_second && left_has_second) {  // comp/comp
+        if (above0 == left0 && above1 == left1)
+          pred_context =
+              3 * (CHECK_LAST_OR_LAST2(above0) || CHECK_LAST_OR_LAST2(above1) ||
+                   CHECK_LAST_OR_LAST2(left0) || CHECK_LAST_OR_LAST2(left1));
+        else
+          pred_context = 2;
+      } else if (above_has_second || left_has_second) {  // single/comp
+        const MV_REFERENCE_FRAME rfs = !above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf1 = above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf2 = above_has_second ? above1 : left1;
+
+        if (CHECK_LAST_OR_LAST2(rfs))
+          pred_context =
+              3 + (CHECK_LAST_OR_LAST2(crf1) || CHECK_LAST_OR_LAST2(crf2));
+        else if (CHECK_GOLDEN_OR_LAST3(rfs))
+          pred_context =
+              (CHECK_LAST_OR_LAST2(crf1) || CHECK_LAST_OR_LAST2(crf2));
+        else
+          pred_context =
+              1 + 2 * (CHECK_LAST_OR_LAST2(crf1) || CHECK_LAST_OR_LAST2(crf2));
+      } else {  // single/single
+        if (CHECK_BACKWARD_REFS(above0) && CHECK_BACKWARD_REFS(left0)) {
+          pred_context = 2 + (above0 == left0);
+        } else if (CHECK_BACKWARD_REFS(above0) || CHECK_BACKWARD_REFS(left0)) {
+          const MV_REFERENCE_FRAME edge0 =
+              CHECK_BACKWARD_REFS(above0) ? left0 : above0;
+          pred_context = 4 * CHECK_LAST_OR_LAST2(edge0);
+        } else {
+          pred_context =
+              2 * CHECK_LAST_OR_LAST2(above0) + 2 * CHECK_LAST_OR_LAST2(left0);
+        }
+      }
+    }
+  } else if (has_above || has_left) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;
+
+    if (!is_inter_block(edge_mbmi) ||
+        (CHECK_BACKWARD_REFS(edge_mbmi->ref_frame[0]) &&
+         !has_second_ref(edge_mbmi)))
+      pred_context = 2;
+    else if (!has_second_ref(edge_mbmi))  // single
+      pred_context = 4 * (CHECK_LAST_OR_LAST2(edge_mbmi->ref_frame[0]));
+    else  // comp
+      pred_context = 3 * (CHECK_LAST_OR_LAST2(edge_mbmi->ref_frame[0]) ||
+                          CHECK_LAST_OR_LAST2(edge_mbmi->ref_frame[1]));
+  } else {  // no edges available (2)
+    pred_context = 2;
+  }
+
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+  return pred_context;
+}
+
+// For the bit to signal whether the single reference is LAST2_FRAME or
+// LAST_FRAME, knowing that it shall be either of these 2 choices.
+//
+// NOTE(zoeliu): The probability of ref_frame[0] is LAST2_FRAME, conditioning
+// on it is either LAST2_FRAME/LAST_FRAME.
+int av1_get_pred_context_single_ref_p4(const MACROBLOCKD *xd) {
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int has_above = xd->up_available;
+  const int has_left = xd->left_available;
+
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries correpsonding to real macroblocks.
+  // The prediction flags in these dummy entries are initialised to 0.
+  if (has_above && has_left) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter or inter/intra
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+      if (!has_second_ref(edge_mbmi)) {  // single
+        if (!CHECK_LAST_OR_LAST2(edge_mbmi->ref_frame[0]))
+          pred_context = 3;
+        else
+          pred_context = 4 * (edge_mbmi->ref_frame[0] == LAST_FRAME);
+      } else {  // comp
+        pred_context = 1 +
+                       2 * (edge_mbmi->ref_frame[0] == LAST_FRAME ||
+                            edge_mbmi->ref_frame[1] == LAST_FRAME);
+      }
+    } else {  // inter/inter
+      const int above_has_second = has_second_ref(above_mbmi);
+      const int left_has_second = has_second_ref(left_mbmi);
+      const MV_REFERENCE_FRAME above0 = above_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME above1 = above_mbmi->ref_frame[1];
+      const MV_REFERENCE_FRAME left0 = left_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME left1 = left_mbmi->ref_frame[1];
+
+      if (above_has_second && left_has_second) {  // comp/comp
+        if (above0 == left0 && above1 == left1)
+          pred_context = 3 * (above0 == LAST_FRAME || above1 == LAST_FRAME ||
+                              left0 == LAST_FRAME || left1 == LAST_FRAME);
+        else
+          pred_context = 2;
+      } else if (above_has_second || left_has_second) {  // single/comp
+        const MV_REFERENCE_FRAME rfs = !above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf1 = above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf2 = above_has_second ? above1 : left1;
+
+        if (rfs == LAST_FRAME)
+          pred_context = 3 + (crf1 == LAST_FRAME || crf2 == LAST_FRAME);
+        else if (rfs == LAST2_FRAME)
+          pred_context = (crf1 == LAST_FRAME || crf2 == LAST_FRAME);
+        else
+          pred_context = 1 + 2 * (crf1 == LAST_FRAME || crf2 == LAST_FRAME);
+      } else {  // single/single
+        if (!CHECK_LAST_OR_LAST2(above0) && !CHECK_LAST_OR_LAST2(left0)) {
+          pred_context = 2 + (above0 == left0);
+        } else if (!CHECK_LAST_OR_LAST2(above0) ||
+                   !CHECK_LAST_OR_LAST2(left0)) {
+          const MV_REFERENCE_FRAME edge0 =
+              !CHECK_LAST_OR_LAST2(above0) ? left0 : above0;
+          pred_context = 4 * (edge0 == LAST_FRAME);
+        } else {
+          pred_context = 2 * (above0 == LAST_FRAME) + 2 * (left0 == LAST_FRAME);
+        }
+      }
+    }
+  } else if (has_above || has_left) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;
+
+    if (!is_inter_block(edge_mbmi) ||
+        (!CHECK_LAST_OR_LAST2(edge_mbmi->ref_frame[0]) &&
+         !has_second_ref(edge_mbmi)))
+      pred_context = 2;
+    else if (!has_second_ref(edge_mbmi))  // single
+      pred_context = 4 * (edge_mbmi->ref_frame[0] == LAST_FRAME);
+    else  // comp
+      pred_context = 3 * (edge_mbmi->ref_frame[0] == LAST_FRAME ||
+                          edge_mbmi->ref_frame[1] == LAST_FRAME);
+  } else {  // no edges available (2)
+    pred_context = 2;
+  }
+
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+  return pred_context;
+}
+
+// For the bit to signal whether the single reference is GOLDEN_FRAME or
+// LAST3_FRAME, knowing that it shall be either of these 2 choices.
+//
+// NOTE(zoeliu): The probability of ref_frame[0] is GOLDEN_FRAME, conditioning
+// on it is either GOLDEN_FRAME/LAST3_FRAME.
+int av1_get_pred_context_single_ref_p5(const MACROBLOCKD *xd) {
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int has_above = xd->up_available;
+  const int has_left = xd->left_available;
+
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries correpsonding to real macroblocks.
+  // The prediction flags in these dummy entries are initialised to 0.
+  if (has_above && has_left) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter or inter/intra
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+      if (!has_second_ref(edge_mbmi)) {  // single
+        if (!CHECK_GOLDEN_OR_LAST3(edge_mbmi->ref_frame[0]))
+          pred_context = 3;
+        else
+          pred_context = 4 * (edge_mbmi->ref_frame[0] == LAST3_FRAME);
+      } else {  // comp
+        pred_context = 1 +
+                       2 * (edge_mbmi->ref_frame[0] == LAST3_FRAME ||
+                            edge_mbmi->ref_frame[1] == LAST3_FRAME);
+      }
+    } else {  // inter/inter
+      const int above_has_second = has_second_ref(above_mbmi);
+      const int left_has_second = has_second_ref(left_mbmi);
+      const MV_REFERENCE_FRAME above0 = above_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME above1 = above_mbmi->ref_frame[1];
+      const MV_REFERENCE_FRAME left0 = left_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME left1 = left_mbmi->ref_frame[1];
+
+      if (above_has_second && left_has_second) {  // comp/comp
+        if (above0 == left0 && above1 == left1)
+          pred_context = 3 * (above0 == LAST3_FRAME || above1 == LAST3_FRAME ||
+                              left0 == LAST3_FRAME || left1 == LAST3_FRAME);
+        else
+          pred_context = 2;
+      } else if (above_has_second || left_has_second) {  // single/comp
+        const MV_REFERENCE_FRAME rfs = !above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf1 = above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf2 = above_has_second ? above1 : left1;
+
+        if (rfs == LAST3_FRAME)
+          pred_context = 3 + (crf1 == LAST3_FRAME || crf2 == LAST3_FRAME);
+        else if (rfs == GOLDEN_FRAME)
+          pred_context = (crf1 == LAST3_FRAME || crf2 == LAST3_FRAME);
+        else
+          pred_context = 1 + 2 * (crf1 == LAST3_FRAME || crf2 == LAST3_FRAME);
+      } else {  // single/single
+        if (!CHECK_GOLDEN_OR_LAST3(above0) && !CHECK_GOLDEN_OR_LAST3(left0)) {
+          pred_context = 2 + (above0 == left0);
+        } else if (!CHECK_GOLDEN_OR_LAST3(above0) ||
+                   !CHECK_GOLDEN_OR_LAST3(left0)) {
+          const MV_REFERENCE_FRAME edge0 =
+              !CHECK_GOLDEN_OR_LAST3(above0) ? left0 : above0;
+          pred_context = 4 * (edge0 == LAST3_FRAME);
+        } else {
+          pred_context =
+              2 * (above0 == LAST3_FRAME) + 2 * (left0 == LAST3_FRAME);
+        }
+      }
+    }
+  } else if (has_above || has_left) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;
+
+    if (!is_inter_block(edge_mbmi) ||
+        (!CHECK_GOLDEN_OR_LAST3(edge_mbmi->ref_frame[0]) &&
+         !has_second_ref(edge_mbmi)))
+      pred_context = 2;
+    else if (!has_second_ref(edge_mbmi))  // single
+      pred_context = 4 * (edge_mbmi->ref_frame[0] == LAST3_FRAME);
+    else  // comp
+      pred_context = 3 * (edge_mbmi->ref_frame[0] == LAST3_FRAME ||
+                          edge_mbmi->ref_frame[1] == LAST3_FRAME);
+  } else {  // no edges available (2)
+    pred_context = 2;
+  }
+
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+  return pred_context;
+}
+
+#else  // CONFIG_EXT_REFS
+
+int av1_get_pred_context_single_ref_p1(const MACROBLOCKD *xd) {
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int has_above = xd->up_available;
+  const int has_left = xd->left_available;
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries corresponding to real macroblocks.
+  // The prediction flags in these dummy entries are initialized to 0.
+  if (has_above && has_left) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter or inter/intra
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+      if (!has_second_ref(edge_mbmi))
+        pred_context = 4 * (edge_mbmi->ref_frame[0] == LAST_FRAME);
+      else
+        pred_context = 1 + (edge_mbmi->ref_frame[0] == LAST_FRAME ||
+                            edge_mbmi->ref_frame[1] == LAST_FRAME);
+    } else {  // inter/inter
+      const int above_has_second = has_second_ref(above_mbmi);
+      const int left_has_second = has_second_ref(left_mbmi);
+      const MV_REFERENCE_FRAME above0 = above_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME above1 = above_mbmi->ref_frame[1];
+      const MV_REFERENCE_FRAME left0 = left_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME left1 = left_mbmi->ref_frame[1];
+
+      if (above_has_second && left_has_second) {
+        pred_context = 1 + (above0 == LAST_FRAME || above1 == LAST_FRAME ||
+                            left0 == LAST_FRAME || left1 == LAST_FRAME);
+      } else if (above_has_second || left_has_second) {
+        const MV_REFERENCE_FRAME rfs = !above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf1 = above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf2 = above_has_second ? above1 : left1;
+
+        if (rfs == LAST_FRAME)
+          pred_context = 3 + (crf1 == LAST_FRAME || crf2 == LAST_FRAME);
+        else
+          pred_context = (crf1 == LAST_FRAME || crf2 == LAST_FRAME);
+      } else {
+        pred_context = 2 * (above0 == LAST_FRAME) + 2 * (left0 == LAST_FRAME);
+      }
+    }
+  } else if (has_above || has_left) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;
+    if (!is_inter_block(edge_mbmi)) {  // intra
+      pred_context = 2;
+    } else {  // inter
+      if (!has_second_ref(edge_mbmi))
+        pred_context = 4 * (edge_mbmi->ref_frame[0] == LAST_FRAME);
+      else
+        pred_context = 1 + (edge_mbmi->ref_frame[0] == LAST_FRAME ||
+                            edge_mbmi->ref_frame[1] == LAST_FRAME);
+    }
+  } else {  // no edges available
+    pred_context = 2;
+  }
+
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+  return pred_context;
+}
+
+int av1_get_pred_context_single_ref_p2(const MACROBLOCKD *xd) {
+  int pred_context;
+  const MB_MODE_INFO *const above_mbmi = xd->above_mbmi;
+  const MB_MODE_INFO *const left_mbmi = xd->left_mbmi;
+  const int has_above = xd->up_available;
+  const int has_left = xd->left_available;
+
+  // Note:
+  // The mode info data structure has a one element border above and to the
+  // left of the entries corresponding to real macroblocks.
+  // The prediction flags in these dummy entries are initialized to 0.
+  if (has_above && has_left) {  // both edges available
+    const int above_intra = !is_inter_block(above_mbmi);
+    const int left_intra = !is_inter_block(left_mbmi);
+
+    if (above_intra && left_intra) {  // intra/intra
+      pred_context = 2;
+    } else if (above_intra || left_intra) {  // intra/inter or inter/intra
+      const MB_MODE_INFO *edge_mbmi = above_intra ? left_mbmi : above_mbmi;
+      if (!has_second_ref(edge_mbmi)) {
+        if (edge_mbmi->ref_frame[0] == LAST_FRAME)
+          pred_context = 3;
+        else
+          pred_context = 4 * (edge_mbmi->ref_frame[0] == GOLDEN_FRAME);
+      } else {
+        pred_context = 1 +
+                       2 * (edge_mbmi->ref_frame[0] == GOLDEN_FRAME ||
+                            edge_mbmi->ref_frame[1] == GOLDEN_FRAME);
+      }
+    } else {  // inter/inter
+      const int above_has_second = has_second_ref(above_mbmi);
+      const int left_has_second = has_second_ref(left_mbmi);
+      const MV_REFERENCE_FRAME above0 = above_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME above1 = above_mbmi->ref_frame[1];
+      const MV_REFERENCE_FRAME left0 = left_mbmi->ref_frame[0];
+      const MV_REFERENCE_FRAME left1 = left_mbmi->ref_frame[1];
+
+      if (above_has_second && left_has_second) {
+        if (above0 == left0 && above1 == left1)
+          pred_context =
+              3 * (above0 == GOLDEN_FRAME || above1 == GOLDEN_FRAME ||
+                   left0 == GOLDEN_FRAME || left1 == GOLDEN_FRAME);
+        else
+          pred_context = 2;
+      } else if (above_has_second || left_has_second) {
+        const MV_REFERENCE_FRAME rfs = !above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf1 = above_has_second ? above0 : left0;
+        const MV_REFERENCE_FRAME crf2 = above_has_second ? above1 : left1;
+
+        if (rfs == GOLDEN_FRAME)
+          pred_context = 3 + (crf1 == GOLDEN_FRAME || crf2 == GOLDEN_FRAME);
+        else if (rfs != GOLDEN_FRAME && rfs != LAST_FRAME)
+          pred_context = crf1 == GOLDEN_FRAME || crf2 == GOLDEN_FRAME;
+        else
+          pred_context = 1 + 2 * (crf1 == GOLDEN_FRAME || crf2 == GOLDEN_FRAME);
+      } else {
+        if (above0 == LAST_FRAME && left0 == LAST_FRAME) {
+          pred_context = 3;
+        } else if (above0 == LAST_FRAME || left0 == LAST_FRAME) {
+          const MV_REFERENCE_FRAME edge0 =
+              (above0 == LAST_FRAME) ? left0 : above0;
+          pred_context = 4 * (edge0 == GOLDEN_FRAME);
+        } else {
+          pred_context =
+              2 * (above0 == GOLDEN_FRAME) + 2 * (left0 == GOLDEN_FRAME);
+        }
+      }
+    }
+  } else if (has_above || has_left) {  // one edge available
+    const MB_MODE_INFO *edge_mbmi = has_above ? above_mbmi : left_mbmi;
+
+    if (!is_inter_block(edge_mbmi) ||
+        (edge_mbmi->ref_frame[0] == LAST_FRAME && !has_second_ref(edge_mbmi)))
+      pred_context = 2;
+    else if (!has_second_ref(edge_mbmi))
+      pred_context = 4 * (edge_mbmi->ref_frame[0] == GOLDEN_FRAME);
+    else
+      pred_context = 3 * (edge_mbmi->ref_frame[0] == GOLDEN_FRAME ||
+                          edge_mbmi->ref_frame[1] == GOLDEN_FRAME);
+  } else {  // no edges available (2)
+    pred_context = 2;
+  }
+  assert(pred_context >= 0 && pred_context < REF_CONTEXTS);
+  return pred_context;
+}
+
+#endif  // CONFIG_EXT_REFS