Add HEVC decoder

Initially written by Guillaume Martres <smarter@ubuntu.com> as a GSoC
project. Further contributions by the OpenHEVC project and other
developers, namely:

Mickaël Raulet <mraulet@insa-rennes.fr>
Seppo Tomperi <seppo.tomperi@vtt.fi>
Gildas Cocherel <gildas.cocherel@laposte.net>
Khaled Jerbi <khaled_jerbi@yahoo.fr>
Wassim Hamidouche <wassim.hamidouche@insa-rennes.fr>
Vittorio Giovara <vittorio.giovara@gmail.com>
Jan Ekström <jeebjp@gmail.com>
Anton Khirnov <anton@khirnov.net>
Martin Storsjö <martin@martin.st>
Luca Barbato <lu_zero@gentoo.org>
Yusuke Nakamura <muken.the.vfrmaniac@gmail.com>
Reimar Döffinger <Reimar.Doeffinger@gmx.de>
Diego Biurrun <diego@biurrun.de>

Signed-off-by: Anton Khirnov <anton@khirnov.net>

1 files changed, 816 insertions, 0 deletions

diff --git a/libavcodec/hevc_mvs.c b/libavcodec/hevc_mvs.c
new file mode 100644
index 0000000000..49d5ff25d8
--- /dev/null
+++ b/libavcodec/hevc_mvs.c
@@ -0,0 +1,816 @@
+/*
+ * HEVC video decoder
+ *
+ * Copyright (C) 2012 - 2013 Guillaume Martres
+ * Copyright (C) 2013 Anand Meher Kotra
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "hevc.h"
+
+static const uint8_t l0_l1_cand_idx[12][2] = {
+    { 0, 1, },
+    { 1, 0, },
+    { 0, 2, },
+    { 2, 0, },
+    { 1, 2, },
+    { 2, 1, },
+    { 0, 3, },
+    { 3, 0, },
+    { 1, 3, },
+    { 3, 1, },
+    { 2, 3, },
+    { 3, 2, },
+};
+
+void ff_hevc_set_neighbour_available(HEVCContext *s, int x0, int y0,
+                                     int nPbW, int nPbH)
+{
+    HEVCLocalContext *lc = &s->HEVClc;
+    int x0b = x0 & ((1 << s->sps->log2_ctb_size) - 1);
+    int y0b = y0 & ((1 << s->sps->log2_ctb_size) - 1);
+
+    lc->na.cand_up       = (lc->ctb_up_flag   || y0b);
+    lc->na.cand_left     = (lc->ctb_left_flag || x0b);
+    lc->na.cand_up_left  = (!x0b && !y0b) ? lc->ctb_up_left_flag : lc->na.cand_left && lc->na.cand_up;
+    lc->na.cand_up_right_sap =
+            ((x0b + nPbW) == (1 << s->sps->log2_ctb_size)) ?
+                    lc->ctb_up_right_flag && !y0b : lc->na.cand_up;
+    lc->na.cand_up_right =
+            ((x0b + nPbW) == (1 << s->sps->log2_ctb_size) ?
+                    lc->ctb_up_right_flag && !y0b : lc->na.cand_up )
+                     && (x0 + nPbW) < lc->end_of_tiles_x;
+    lc->na.cand_bottom_left = ((y0 + nPbH) >= lc->end_of_tiles_y) ? 0 : lc->na.cand_left;
+}
+
+/*
+ * 6.4.1 Derivation process for z-scan order block availability
+ */
+static int z_scan_block_avail(HEVCContext *s, int xCurr, int yCurr,
+                              int xN, int yN)
+{
+#define MIN_TB_ADDR_ZS(x, y)                                            \
+    s->pps->min_tb_addr_zs[(y) * s->sps->min_tb_width + (x)]
+    int Curr = MIN_TB_ADDR_ZS(xCurr >> s->sps->log2_min_tb_size,
+                              yCurr >> s->sps->log2_min_tb_size);
+    int N;
+
+    if (xN < 0 || yN < 0 ||
+        xN >= s->sps->width ||
+        yN >= s->sps->height)
+        return 0;
+
+    N = MIN_TB_ADDR_ZS(xN >> s->sps->log2_min_tb_size,
+                       yN >> s->sps->log2_min_tb_size);
+
+    return N <= Curr;
+}
+
+static int same_prediction_block(HEVCLocalContext *lc, int log2_cb_size,
+                                 int x0, int y0, int nPbW, int nPbH,
+                                 int xA1, int yA1, int partIdx)
+{
+    return !(nPbW << 1 == 1 << log2_cb_size &&
+             nPbH << 1 == 1 << log2_cb_size && partIdx == 1 &&
+             lc->cu.x + nPbW > xA1 &&
+             lc->cu.y + nPbH <= yA1);
+}
+
+/*
+ * 6.4.2 Derivation process for prediction block availability
+ */
+static int check_prediction_block_available(HEVCContext *s, int log2_cb_size,
+                                            int x0, int y0, int nPbW, int nPbH,
+                                            int xA1, int yA1, int partIdx)
+{
+    HEVCLocalContext *lc = &s->HEVClc;
+
+    if (lc->cu.x < xA1 && lc->cu.y < yA1 &&
+        (lc->cu.x + (1 << log2_cb_size)) > xA1 &&
+        (lc->cu.y + (1 << log2_cb_size)) > yA1)
+        return same_prediction_block(lc, log2_cb_size, x0, y0,
+                                     nPbW, nPbH, xA1, yA1, partIdx);
+    else
+        return z_scan_block_avail(s, x0, y0, xA1, yA1);
+}
+
+//check if the two luma locations belong to the same mostion estimation region
+static int isDiffMER(HEVCContext *s, int xN, int yN, int xP, int yP)
+{
+    uint8_t plevel = s->pps->log2_parallel_merge_level;
+
+    return xN >> plevel == xP >> plevel &&
+           yN >> plevel == yP >> plevel;
+}
+
+#define MATCH(x) (A.x == B.x)
+
+// check if the mv's and refidx are the same between A and B
+static int compareMVrefidx(struct MvField A, struct MvField B)
+{
+    if (A.pred_flag[0] && A.pred_flag[1] && B.pred_flag[0] && B.pred_flag[1])
+        return MATCH(ref_idx[0]) && MATCH(mv[0].x) && MATCH(mv[0].y) &&
+               MATCH(ref_idx[1]) && MATCH(mv[1].x) && MATCH(mv[1].y);
+
+    if (A.pred_flag[0] && !A.pred_flag[1] && B.pred_flag[0] && !B.pred_flag[1])
+        return MATCH(ref_idx[0]) && MATCH(mv[0].x) && MATCH(mv[0].y);
+
+    if (!A.pred_flag[0] && A.pred_flag[1] && !B.pred_flag[0] && B.pred_flag[1])
+        return MATCH(ref_idx[1]) && MATCH(mv[1].x) && MATCH(mv[1].y);
+
+    return 0;
+}
+
+static av_always_inline void mv_scale(Mv *dst, Mv *src, int td, int tb)
+{
+    int tx, scale_factor;
+
+    td = av_clip_int8_c(td);
+    tb = av_clip_int8_c(tb);
+    tx = (0x4000 + abs(td / 2)) / td;
+    scale_factor = av_clip_c((tb * tx + 32) >> 6, -4096, 4095);
+    dst->x = av_clip_int16_c((scale_factor * src->x + 127 +
+                             (scale_factor * src->x < 0)) >> 8);
+    dst->y = av_clip_int16_c((scale_factor * src->y + 127 +
+                             (scale_factor * src->y < 0)) >> 8);
+}
+
+static int check_mvset(Mv *mvLXCol, Mv *mvCol,
+                       int colPic, int poc,
+                       RefPicList *refPicList, int X, int refIdxLx,
+                       RefPicList *refPicList_col, int listCol, int refidxCol)
+{
+    int cur_lt = refPicList[X].isLongTerm[refIdxLx];
+    int col_lt = refPicList_col[listCol].isLongTerm[refidxCol];
+    int col_poc_diff, cur_poc_diff;
+
+    if (cur_lt != col_lt) {
+        mvLXCol->x = 0;
+        mvLXCol->y = 0;
+        return 0;
+    }
+
+    col_poc_diff = colPic - refPicList_col[listCol].list[refidxCol];
+    cur_poc_diff = poc    - refPicList[X].list[refIdxLx];
+
+    if (!col_poc_diff)
+        col_poc_diff = 1;  // error resilience
+
+    if (cur_lt || col_poc_diff == cur_poc_diff) {
+        mvLXCol->x = mvCol->x;
+        mvLXCol->y = mvCol->y;
+    } else {
+        mv_scale(mvLXCol, mvCol, col_poc_diff, cur_poc_diff);
+    }
+    return 1;
+}
+
+#define CHECK_MVSET(l)                                          \
+    check_mvset(mvLXCol, temp_col.mv + l,                       \
+                colPic, s->poc,                                 \
+                refPicList, X, refIdxLx,                        \
+                refPicList_col, L ## l, temp_col.ref_idx[l])
+
+// derive the motion vectors section 8.5.3.1.8
+static int derive_temporal_colocated_mvs(HEVCContext *s, MvField temp_col,
+                                         int refIdxLx, Mv *mvLXCol, int X,
+                                         int colPic, RefPicList *refPicList_col)
+{
+    RefPicList *refPicList = s->ref->refPicList;
+
+    if (temp_col.is_intra) {
+        mvLXCol->x = 0;
+        mvLXCol->y = 0;
+        return 0;
+    }
+
+    if (temp_col.pred_flag[0] == 0)
+        return CHECK_MVSET(1);
+    else if (temp_col.pred_flag[0] == 1 && temp_col.pred_flag[1] == 0)
+        return CHECK_MVSET(0);
+    else if (temp_col.pred_flag[0] == 1 && temp_col.pred_flag[1] == 1) {
+        int check_diffpicount = 0;
+        int i = 0;
+        for (i = 0; i < refPicList[0].nb_refs; i++) {
+            if (refPicList[0].list[i] > s->poc)
+                check_diffpicount++;
+        }
+        for (i = 0; i < refPicList[1].nb_refs; i++) {
+            if (refPicList[1].list[i] > s->poc)
+                check_diffpicount++;
+        }
+        if (check_diffpicount == 0 && X == 0)
+            return CHECK_MVSET(0);
+        else if (check_diffpicount == 0 && X == 1)
+            return CHECK_MVSET(1);
+        else {
+            if (s->sh.collocated_list == L1)
+                return CHECK_MVSET(0);
+            else
+                return CHECK_MVSET(1);
+        }
+    }
+
+    return 0;
+}
+
+#define TAB_MVF(x, y)                                                   \
+    tab_mvf[(y) * min_pu_width + x]
+
+#define TAB_MVF_PU(v)                                                   \
+    TAB_MVF(x ## v ## _pu, y ## v ## _pu)
+
+#define DERIVE_TEMPORAL_COLOCATED_MVS                                   \
+    derive_temporal_colocated_mvs(s, temp_col,                          \
+                                  refIdxLx, mvLXCol, X, colPic,         \
+                                  ff_hevc_get_ref_list(s, ref, x, y))
+
+/*
+ * 8.5.3.1.7  temporal luma motion vector prediction
+ */
+static int temporal_luma_motion_vector(HEVCContext *s, int x0, int y0,
+                                       int nPbW, int nPbH, int refIdxLx,
+                                       Mv *mvLXCol, int X)
+{
+    MvField *tab_mvf;
+    MvField temp_col;
+    int x, y, x_pu, y_pu;
+    int min_pu_width = s->sps->min_pu_width;
+    int availableFlagLXCol = 0;
+    int colPic;
+
+    HEVCFrame *ref = s->ref->collocated_ref;
+
+    if (!ref)
+        return 0;
+
+    tab_mvf = ref->tab_mvf;
+    colPic  = ref->poc;
+
+    //bottom right collocated motion vector
+    x = x0 + nPbW;
+    y = y0 + nPbH;
+
+    ff_thread_await_progress(&ref->tf, y, 0);
+    if (tab_mvf &&
+        (y0 >> s->sps->log2_ctb_size) == (y >> s->sps->log2_ctb_size) &&
+        y < s->sps->height &&
+        x < s->sps->width) {
+        x                  = ((x >> 4) << 4);
+        y                  = ((y >> 4) << 4);
+        x_pu               = x >> s->sps->log2_min_pu_size;
+        y_pu               = y >> s->sps->log2_min_pu_size;
+        temp_col           = TAB_MVF(x_pu, y_pu);
+        availableFlagLXCol = DERIVE_TEMPORAL_COLOCATED_MVS;
+    }
+
+    // derive center collocated motion vector
+    if (tab_mvf && !availableFlagLXCol) {
+        x                  = x0 + (nPbW >> 1);
+        y                  = y0 + (nPbH >> 1);
+        x                  = ((x >> 4) << 4);
+        y                  = ((y >> 4) << 4);
+        x_pu               = x >> s->sps->log2_min_pu_size;
+        y_pu               = y >> s->sps->log2_min_pu_size;
+        temp_col           = TAB_MVF(x_pu, y_pu);
+        availableFlagLXCol = DERIVE_TEMPORAL_COLOCATED_MVS;
+    }
+    return availableFlagLXCol;
+}
+
+#define AVAILABLE(cand, v)                                      \
+    (cand && !TAB_MVF_PU(v).is_intra)
+
+#define PRED_BLOCK_AVAILABLE(v)                                 \
+    check_prediction_block_available(s, log2_cb_size,           \
+                                     x0, y0, nPbW, nPbH,        \
+                                     x ## v, y ## v, part_idx)
+
+#define COMPARE_MV_REFIDX(a, b)                                 \
+    compareMVrefidx(TAB_MVF_PU(a), TAB_MVF_PU(b))
+
+/*
+ * 8.5.3.1.2  Derivation process for spatial merging candidates
+ */
+static void derive_spatial_merge_candidates(HEVCContext *s, int x0, int y0,
+                                            int nPbW, int nPbH,
+                                            int log2_cb_size,
+                                            int singleMCLFlag, int part_idx,
+                                            struct MvField mergecandlist[])
+{
+    HEVCLocalContext *lc   = &s->HEVClc;
+    RefPicList *refPicList = s->ref->refPicList;
+    MvField *tab_mvf       = s->ref->tab_mvf;
+
+    const int min_pu_width = s->sps->min_pu_width;
+
+    const int cand_bottom_left = lc->na.cand_bottom_left;
+    const int cand_left        = lc->na.cand_left;
+    const int cand_up_left     = lc->na.cand_up_left;
+    const int cand_up          = lc->na.cand_up;
+    const int cand_up_right    = lc->na.cand_up_right_sap;
+
+    const int xA1    = x0 - 1;
+    const int yA1    = y0 + nPbH - 1;
+    const int xA1_pu = xA1 >> s->sps->log2_min_pu_size;
+    const int yA1_pu = yA1 >> s->sps->log2_min_pu_size;
+
+    const int xB1    = x0 + nPbW - 1;
+    const int yB1    = y0 - 1;
+    const int xB1_pu = xB1 >> s->sps->log2_min_pu_size;
+    const int yB1_pu = yB1 >> s->sps->log2_min_pu_size;
+
+    const int xB0    = x0 + nPbW;
+    const int yB0    = y0 - 1;
+    const int xB0_pu = xB0 >> s->sps->log2_min_pu_size;
+    const int yB0_pu = yB0 >> s->sps->log2_min_pu_size;
+
+    const int xA0    = x0 - 1;
+    const int yA0    = y0 + nPbH;
+    const int xA0_pu = xA0 >> s->sps->log2_min_pu_size;
+    const int yA0_pu = yA0 >> s->sps->log2_min_pu_size;
+
+    const int xB2    = x0 - 1;
+    const int yB2    = y0 - 1;
+    const int xB2_pu = xB2 >> s->sps->log2_min_pu_size;
+    const int yB2_pu = yB2 >> s->sps->log2_min_pu_size;
+
+    const int nb_refs = (s->sh.slice_type == P_SLICE) ?
+                        s->sh.nb_refs[0] : FFMIN(s->sh.nb_refs[0], s->sh.nb_refs[1]);
+    int check_MER   = 1;
+    int check_MER_1 = 1;
+
+    int zero_idx = 0;
+
+    int nb_merge_cand = 0;
+    int nb_orig_merge_cand = 0;
+
+    int is_available_a0;
+    int is_available_a1;
+    int is_available_b0;
+    int is_available_b1;
+    int is_available_b2;
+    int check_B0;
+    int check_A0;
+
+    //first left spatial merge candidate
+    is_available_a1 = AVAILABLE(cand_left, A1);
+
+    if (!singleMCLFlag && part_idx == 1 &&
+        (lc->cu.part_mode == PART_Nx2N ||
+         lc->cu.part_mode == PART_nLx2N ||
+         lc->cu.part_mode == PART_nRx2N) ||
+        isDiffMER(s, xA1, yA1, x0, y0)) {
+        is_available_a1 = 0;
+    }
+
+    if (is_available_a1)
+        mergecandlist[nb_merge_cand++] = TAB_MVF_PU(A1);
+
+    // above spatial merge candidate
+    is_available_b1 = AVAILABLE(cand_up, B1);
+
+    if (!singleMCLFlag && part_idx == 1 &&
+        (lc->cu.part_mode == PART_2NxN ||
+         lc->cu.part_mode == PART_2NxnU ||
+         lc->cu.part_mode == PART_2NxnD) ||
+        isDiffMER(s, xB1, yB1, x0, y0)) {
+        is_available_b1 = 0;
+    }
+
+    if (is_available_a1 && is_available_b1)
+        check_MER = !COMPARE_MV_REFIDX(B1, A1);
+
+    if (is_available_b1 && check_MER)
+        mergecandlist[nb_merge_cand++] = TAB_MVF_PU(B1);
+
+    // above right spatial merge candidate
+    check_MER = 1;
+    check_B0  = PRED_BLOCK_AVAILABLE(B0);
+
+    is_available_b0 = check_B0 && AVAILABLE(cand_up_right, B0);
+
+    if (isDiffMER(s, xB0, yB0, x0, y0))
+        is_available_b0 = 0;
+
+    if (is_available_b1 && is_available_b0)
+        check_MER = !COMPARE_MV_REFIDX(B0, B1);
+
+    if (is_available_b0 && check_MER)
+        mergecandlist[nb_merge_cand++] = TAB_MVF_PU(B0);
+
+    // left bottom spatial merge candidate
+    check_MER = 1;
+    check_A0  = PRED_BLOCK_AVAILABLE(A0);
+
+    is_available_a0 = check_A0 && AVAILABLE(cand_bottom_left, A0);
+
+    if (isDiffMER(s, xA0, yA0, x0, y0))
+        is_available_a0 = 0;
+
+    if (is_available_a1 && is_available_a0)
+        check_MER = !COMPARE_MV_REFIDX(A0, A1);
+
+    if (is_available_a0 && check_MER)
+        mergecandlist[nb_merge_cand++] = TAB_MVF_PU(A0);
+
+    // above left spatial merge candidate
+    check_MER = 1;
+
+    is_available_b2 = AVAILABLE(cand_up_left, B2);
+
+    if (isDiffMER(s, xB2, yB2, x0, y0))
+        is_available_b2 = 0;
+
+    if (is_available_a1 && is_available_b2)
+        check_MER = !COMPARE_MV_REFIDX(B2, A1);
+
+    if (is_available_b1 && is_available_b2)
+        check_MER_1 = !COMPARE_MV_REFIDX(B2, B1);
+
+    if (is_available_b2 && check_MER && check_MER_1 && nb_merge_cand != 4)
+        mergecandlist[nb_merge_cand++] = TAB_MVF_PU(B2);
+
+    // temporal motion vector candidate
+    if (s->sh.slice_temporal_mvp_enabled_flag &&
+        nb_merge_cand < s->sh.max_num_merge_cand) {
+        Mv mv_l0_col, mv_l1_col;
+        int available_l0 = temporal_luma_motion_vector(s, x0, y0, nPbW, nPbH,
+                                                       0, &mv_l0_col, 0);
+        int available_l1 = (s->sh.slice_type == B_SLICE) ?
+                           temporal_luma_motion_vector(s, x0, y0, nPbW, nPbH,
+                                                       0, &mv_l1_col, 1) : 0;
+
+        if (available_l0 || available_l1) {
+            mergecandlist[nb_merge_cand].is_intra     = 0;
+            mergecandlist[nb_merge_cand].pred_flag[0] = available_l0;
+            mergecandlist[nb_merge_cand].pred_flag[1] = available_l1;
+            if (available_l0) {
+                mergecandlist[nb_merge_cand].mv[0]      = mv_l0_col;
+                mergecandlist[nb_merge_cand].ref_idx[0] = 0;
+            }
+            if (available_l1) {
+                mergecandlist[nb_merge_cand].mv[1]      = mv_l1_col;
+                mergecandlist[nb_merge_cand].ref_idx[1] = 0;
+            }
+            nb_merge_cand++;
+        }
+    }
+
+    nb_orig_merge_cand = nb_merge_cand;
+
+    // combined bi-predictive merge candidates  (applies for B slices)
+    if (s->sh.slice_type == B_SLICE && nb_orig_merge_cand > 1 &&
+        nb_orig_merge_cand < s->sh.max_num_merge_cand) {
+        int comb_idx;
+
+        for (comb_idx = 0; nb_merge_cand < s->sh.max_num_merge_cand &&
+                           comb_idx < nb_orig_merge_cand * (nb_orig_merge_cand - 1); comb_idx++) {
+            int l0_cand_idx = l0_l1_cand_idx[comb_idx][0];
+            int l1_cand_idx = l0_l1_cand_idx[comb_idx][1];
+            MvField l0_cand = mergecandlist[l0_cand_idx];
+            MvField l1_cand = mergecandlist[l1_cand_idx];
+
+            if (l0_cand.pred_flag[0] && l1_cand.pred_flag[1] &&
+                (refPicList[0].list[l0_cand.ref_idx[0]] !=
+                 refPicList[1].list[l1_cand.ref_idx[1]] ||
+                 l0_cand.mv[0].x != l1_cand.mv[1].x ||
+                 l0_cand.mv[0].y != l1_cand.mv[1].y)) {
+                mergecandlist[nb_merge_cand].ref_idx[0]   = l0_cand.ref_idx[0];
+                mergecandlist[nb_merge_cand].ref_idx[1]   = l1_cand.ref_idx[1];
+                mergecandlist[nb_merge_cand].pred_flag[0] = 1;
+                mergecandlist[nb_merge_cand].pred_flag[1] = 1;
+                mergecandlist[nb_merge_cand].mv[0].x      = l0_cand.mv[0].x;
+                mergecandlist[nb_merge_cand].mv[0].y      = l0_cand.mv[0].y;
+                mergecandlist[nb_merge_cand].mv[1].x      = l1_cand.mv[1].x;
+                mergecandlist[nb_merge_cand].mv[1].y      = l1_cand.mv[1].y;
+                mergecandlist[nb_merge_cand].is_intra     = 0;
+                nb_merge_cand++;
+            }
+        }
+    }
+
+    // append Zero motion vector candidates
+    while (nb_merge_cand < s->sh.max_num_merge_cand) {
+        mergecandlist[nb_merge_cand].pred_flag[0] = 1;
+        mergecandlist[nb_merge_cand].pred_flag[1] = s->sh.slice_type == B_SLICE;
+        mergecandlist[nb_merge_cand].mv[0].x      = 0;
+        mergecandlist[nb_merge_cand].mv[0].y      = 0;
+        mergecandlist[nb_merge_cand].mv[1].x      = 0;
+        mergecandlist[nb_merge_cand].mv[1].y      = 0;
+        mergecandlist[nb_merge_cand].is_intra     = 0;
+        mergecandlist[nb_merge_cand].ref_idx[0]   = zero_idx < nb_refs ? zero_idx : 0;
+        mergecandlist[nb_merge_cand].ref_idx[1]   = zero_idx < nb_refs ? zero_idx : 0;
+
+        nb_merge_cand++;
+        zero_idx++;
+    }
+}
+
+/*
+ * 8.5.3.1.1 Derivation process of luma Mvs for merge mode
+ */
+void ff_hevc_luma_mv_merge_mode(HEVCContext *s, int x0, int y0, int nPbW,
+                                int nPbH, int log2_cb_size, int part_idx,
+                                int merge_idx, MvField *mv)
+{
+    int singleMCLFlag = 0;
+    int nCS = 1 << log2_cb_size;
+    struct MvField mergecand_list[MRG_MAX_NUM_CANDS] = { { { { 0 } } } };
+    int nPbW2 = nPbW;
+    int nPbH2 = nPbH;
+    HEVCLocalContext *lc = &s->HEVClc;
+
+    if (s->pps->log2_parallel_merge_level > 2 && nCS == 8) {
+        singleMCLFlag = 1;
+        x0            = lc->cu.x;
+        y0            = lc->cu.y;
+        nPbW          = nCS;
+        nPbH          = nCS;
+        part_idx      = 0;
+    }
+
+    ff_hevc_set_neighbour_available(s, x0, y0, nPbW, nPbH);
+    derive_spatial_merge_candidates(s, x0, y0, nPbW, nPbH, log2_cb_size,
+                                    singleMCLFlag, part_idx, mergecand_list);
+
+    if (mergecand_list[merge_idx].pred_flag[0] == 1 &&
+        mergecand_list[merge_idx].pred_flag[1] == 1 &&
+        (nPbW2 + nPbH2) == 12) {
+        mergecand_list[merge_idx].ref_idx[1]   = -1;
+        mergecand_list[merge_idx].pred_flag[1] = 0;
+    }
+
+    *mv = mergecand_list[merge_idx];
+}
+
+static av_always_inline void dist_scale(HEVCContext *s, Mv *mv,
+                                        int min_pu_width, int x, int y,
+                                        int elist, int ref_idx_curr, int ref_idx)
+{
+    RefPicList *refPicList = s->ref->refPicList;
+    MvField *tab_mvf       = s->ref->tab_mvf;
+    int ref_pic_elist      = refPicList[elist].list[TAB_MVF(x, y).ref_idx[elist]];
+    int ref_pic_curr       = refPicList[ref_idx_curr].list[ref_idx];
+
+    if (ref_pic_elist != ref_pic_curr)
+        mv_scale(mv, mv, s->poc - ref_pic_elist, s->poc - ref_pic_curr);
+}
+
+static int mv_mp_mode_mx(HEVCContext *s, int x, int y, int pred_flag_index,
+                         Mv *mv, int ref_idx_curr, int ref_idx)
+{
+    MvField *tab_mvf = s->ref->tab_mvf;
+    int min_pu_width = s->sps->min_pu_width;
+
+    RefPicList *refPicList = s->ref->refPicList;
+
+    if (TAB_MVF(x, y).pred_flag[pred_flag_index] == 1 &&
+        refPicList[pred_flag_index].list[TAB_MVF(x, y).ref_idx[pred_flag_index]] == refPicList[ref_idx_curr].list[ref_idx]) {
+        *mv = TAB_MVF(x, y).mv[pred_flag_index];
+        return 1;
+    }
+    return 0;
+}
+
+static int mv_mp_mode_mx_lt(HEVCContext *s, int x, int y, int pred_flag_index,
+                            Mv *mv, int ref_idx_curr, int ref_idx)
+{
+    MvField *tab_mvf = s->ref->tab_mvf;
+    int min_pu_width = s->sps->min_pu_width;
+
+    RefPicList *refPicList = s->ref->refPicList;
+    int currIsLongTerm     = refPicList[ref_idx_curr].isLongTerm[ref_idx];
+
+    int colIsLongTerm =
+        refPicList[pred_flag_index].isLongTerm[(TAB_MVF(x, y).ref_idx[pred_flag_index])];
+
+    if (TAB_MVF(x, y).pred_flag[pred_flag_index] &&
+        colIsLongTerm == currIsLongTerm) {
+        *mv = TAB_MVF(x, y).mv[pred_flag_index];
+        if (!currIsLongTerm)
+            dist_scale(s, mv, min_pu_width, x, y,
+                       pred_flag_index, ref_idx_curr, ref_idx);
+        return 1;
+    }
+    return 0;
+}
+
+#define MP_MX(v, pred, mx)                                      \
+    mv_mp_mode_mx(s, x ## v ## _pu, y ## v ## _pu, pred,        \
+                  &mx, ref_idx_curr, ref_idx)
+
+#define MP_MX_LT(v, pred, mx)                                   \
+    mv_mp_mode_mx_lt(s, x ## v ## _pu, y ## v ## _pu, pred,     \
+                     &mx, ref_idx_curr, ref_idx)
+
+void ff_hevc_luma_mv_mvp_mode(HEVCContext *s, int x0, int y0, int nPbW,
+                              int nPbH, int log2_cb_size, int part_idx,
+                              int merge_idx, MvField *mv,
+                              int mvp_lx_flag, int LX)
+{
+    HEVCLocalContext *lc = &s->HEVClc;
+    MvField *tab_mvf = s->ref->tab_mvf;
+    int isScaledFlag_L0 = 0;
+    int availableFlagLXA0 = 0;
+    int availableFlagLXB0 = 0;
+    int numMVPCandLX = 0;
+    int min_pu_width = s->sps->min_pu_width;
+
+    int xA0, yA0;
+    int xA0_pu, yA0_pu;
+    int is_available_a0;
+
+    int xA1, yA1;
+    int xA1_pu, yA1_pu;
+    int is_available_a1;
+
+    int xB0, yB0;
+    int xB0_pu, yB0_pu;
+    int is_available_b0;
+
+    int xB1, yB1;
+    int xB1_pu = 0, yB1_pu = 0;
+    int is_available_b1 = 0;
+
+    int xB2, yB2;
+    int xB2_pu = 0, yB2_pu = 0;
+    int is_available_b2 = 0;
+    Mv mvpcand_list[2] = { { 0 } };
+    Mv mxA = { 0 };
+    Mv mxB = { 0 };
+    int ref_idx_curr = 0;
+    int ref_idx = 0;
+    int pred_flag_index_l0;
+    int pred_flag_index_l1;
+    int x0b = x0 & ((1 << s->sps->log2_ctb_size) - 1);
+    int y0b = y0 & ((1 << s->sps->log2_ctb_size) - 1);
+
+    int cand_up = (lc->ctb_up_flag || y0b);
+    int cand_left = (lc->ctb_left_flag || x0b);
+    int cand_up_left =
+            (!x0b && !y0b) ? lc->ctb_up_left_flag : cand_left && cand_up;
+    int cand_up_right =
+            (x0b + nPbW == (1 << s->sps->log2_ctb_size) ||
+             x0  + nPbW >= lc->end_of_tiles_x) ? lc->ctb_up_right_flag && !y0b
+                                               : cand_up;
+    int cand_bottom_left = (y0 + nPbH >= lc->end_of_tiles_y) ? 0 : cand_left;
+
+    ref_idx_curr       = LX;
+    ref_idx            = mv->ref_idx[LX];
+    pred_flag_index_l0 = LX;
+    pred_flag_index_l1 = !LX;
+
+    // left bottom spatial candidate
+    xA0 = x0 - 1;
+    yA0 = y0 + nPbH;
+    xA0_pu = xA0 >> s->sps->log2_min_pu_size;
+    yA0_pu = yA0 >> s->sps->log2_min_pu_size;
+
+    is_available_a0 = PRED_BLOCK_AVAILABLE(A0) && AVAILABLE(cand_bottom_left, A0);
+
+    //left spatial merge candidate
+    xA1    = x0 - 1;
+    yA1    = y0 + nPbH - 1;
+    xA1_pu = xA1 >> s->sps->log2_min_pu_size;
+    yA1_pu = yA1 >> s->sps->log2_min_pu_size;
+
+    is_available_a1 = AVAILABLE(cand_left, A1);
+    if (is_available_a0 || is_available_a1)
+        isScaledFlag_L0 = 1;
+
+    if (is_available_a0) {
+        availableFlagLXA0 = MP_MX(A0, pred_flag_index_l0, mxA);
+        if (!availableFlagLXA0)
+            availableFlagLXA0 = MP_MX(A0, pred_flag_index_l1, mxA);
+    }
+
+    if (is_available_a1 && !availableFlagLXA0) {
+        availableFlagLXA0 = MP_MX(A1, pred_flag_index_l0, mxA);
+        if (!availableFlagLXA0)
+            availableFlagLXA0 = MP_MX(A1, pred_flag_index_l1, mxA);
+    }
+
+    if (is_available_a0 && !availableFlagLXA0) {
+        availableFlagLXA0 = MP_MX_LT(A0, pred_flag_index_l0, mxA);
+        if (!availableFlagLXA0)
+            availableFlagLXA0 = MP_MX_LT(A0, pred_flag_index_l1, mxA);
+    }
+
+    if (is_available_a1 && !availableFlagLXA0) {
+        availableFlagLXA0 = MP_MX_LT(A1, pred_flag_index_l0, mxA);
+        if (!availableFlagLXA0)
+            availableFlagLXA0 = MP_MX_LT(A1, pred_flag_index_l1, mxA);
+    }
+
+    // B candidates
+    // above right spatial merge candidate
+    xB0    = x0 + nPbW;
+    yB0    = y0 - 1;
+    xB0_pu = xB0 >> s->sps->log2_min_pu_size;
+    yB0_pu = yB0 >> s->sps->log2_min_pu_size;
+
+    is_available_b0 = PRED_BLOCK_AVAILABLE(B0) && AVAILABLE(cand_up_right, B0);
+
+    if (is_available_b0) {
+        availableFlagLXB0 = MP_MX(B0, pred_flag_index_l0, mxB);
+        if (!availableFlagLXB0)
+            availableFlagLXB0 = MP_MX(B0, pred_flag_index_l1, mxB);
+    }
+
+    if (!availableFlagLXB0) {
+        // above spatial merge candidate
+        xB1    = x0 + nPbW - 1;
+        yB1    = y0 - 1;
+        xB1_pu = xB1 >> s->sps->log2_min_pu_size;
+        yB1_pu = yB1 >> s->sps->log2_min_pu_size;
+
+        is_available_b1 = AVAILABLE(cand_up, B1);
+
+        if (is_available_b1) {
+            availableFlagLXB0 = MP_MX(B1, pred_flag_index_l0, mxB);
+            if (!availableFlagLXB0)
+                availableFlagLXB0 = MP_MX(B1, pred_flag_index_l1, mxB);
+        }
+    }
+
+    if (!availableFlagLXB0) {
+        // above left spatial merge candidate
+        xB2 = x0 - 1;
+        yB2 = y0 - 1;
+        xB2_pu = xB2 >> s->sps->log2_min_pu_size;
+        yB2_pu = yB2 >> s->sps->log2_min_pu_size;
+        is_available_b2 = AVAILABLE(cand_up_left, B2);
+
+        if (is_available_b2) {
+            availableFlagLXB0 = MP_MX(B2, pred_flag_index_l0, mxB);
+            if (!availableFlagLXB0)
+                availableFlagLXB0 = MP_MX(B2, pred_flag_index_l1, mxB);
+        }
+    }
+
+    if (isScaledFlag_L0 == 0) {
+        if (availableFlagLXB0) {
+            availableFlagLXA0 = 1;
+            mxA = mxB;
+        }
+        availableFlagLXB0 = 0;
+
+        // XB0 and L1
+        if (is_available_b0) {
+            availableFlagLXB0 = MP_MX_LT(B0, pred_flag_index_l0, mxB);
+            if (!availableFlagLXB0)
+                availableFlagLXB0 = MP_MX_LT(B0, pred_flag_index_l1, mxB);
+        }
+
+        if (is_available_b1 && !availableFlagLXB0) {
+            availableFlagLXB0 = MP_MX_LT(B1, pred_flag_index_l0, mxB);
+            if (!availableFlagLXB0)
+                availableFlagLXB0 = MP_MX_LT(B1, pred_flag_index_l1, mxB);
+        }
+
+        if (is_available_b2 && !availableFlagLXB0) {
+            availableFlagLXB0 = MP_MX_LT(B2, pred_flag_index_l0, mxB);
+            if (!availableFlagLXB0)
+                availableFlagLXB0 = MP_MX_LT(B2, pred_flag_index_l1, mxB);
+        }
+    }
+
+    if (availableFlagLXA0)
+        mvpcand_list[numMVPCandLX++] = mxA;
+
+    if (availableFlagLXB0 && (!availableFlagLXA0 || mxA.x != mxB.x || mxA.y != mxB.y))
+        mvpcand_list[numMVPCandLX++] = mxB;
+
+    //temporal motion vector prediction candidate
+    if (numMVPCandLX < 2 && s->sh.slice_temporal_mvp_enabled_flag) {
+        Mv mv_col;
+        int available_col = temporal_luma_motion_vector(s, x0, y0, nPbW,
+                                                        nPbH, ref_idx,
+                                                        &mv_col, LX);
+        if (available_col)
+            mvpcand_list[numMVPCandLX++] = mv_col;
+    }
+
+    // insert zero motion vectors when the number of available candidates are less than 2
+    while (numMVPCandLX < 2)
+        mvpcand_list[numMVPCandLX++] = (Mv){ 0, 0 };
+
+    mv->mv[LX].x = mvpcand_list[mvp_lx_flag].x;
+    mv->mv[LX].y = mvpcand_list[mvp_lx_flag].y;
+}