lavc: VP9 decoder

Originally written by Ronald S. Bultje <rsbultje@gmail.com> and
Clément Bœsch <u@pkh.me>

Further contributions by:
Anton Khirnov <anton@khirnov.net>
Diego Biurrun <diego@biurrun.de>
Luca Barbato <lu_zero@gentoo.org>
Martin Storsjö <martin@martin.st>

Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
Signed-off-by: Anton Khirnov <anton@khirnov.net>

1 files changed, 1684 insertions, 0 deletions

diff --git a/libavcodec/vp9block.c b/libavcodec/vp9block.c
new file mode 100644
index 0000000000..e6865934c4
--- /dev/null
+++ b/libavcodec/vp9block.c
@@ -0,0 +1,1684 @@
+/*
+ * VP9 compatible video decoder
+ *
+ * Copyright (C) 2013 Ronald S. Bultje <rsbultje gmail com>
+ * Copyright (C) 2013 Clément Bœsch <u pkh me>
+ *
+ * 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 "libavutil/avassert.h"
+
+#include "avcodec.h"
+#include "get_bits.h"
+#include "internal.h"
+#include "videodsp.h"
+#include "vp56.h"
+#include "vp9.h"
+#include "vp9data.h"
+
+static const uint8_t bwh_tab[2][N_BS_SIZES][2] = {
+    {
+        { 16, 16 }, { 16, 8 }, { 8, 16 }, { 8, 8 }, { 8, 4 }, { 4, 8 },
+        {  4,  4 }, {  4, 2 }, { 2,  4 }, { 2, 2 }, { 2, 1 }, { 1, 2 }, { 1, 1 },
+    },  {
+        {  8,  8 }, {  8, 4 }, { 4,  8 }, { 4, 4 }, { 4, 2 }, { 2, 4 },
+        {  2,  2 }, {  2, 1 }, { 1,  2 }, { 1, 1 }, { 1, 1 }, { 1, 1 }, { 1, 1 },
+    }
+};
+
+// differential forward probability updates
+static void decode_mode(VP9Context *s, VP9Block *const b)
+{
+    static const uint8_t left_ctx[N_BS_SIZES] = {
+        0x0, 0x8, 0x0, 0x8, 0xc, 0x8, 0xc, 0xe, 0xc, 0xe, 0xf, 0xe, 0xf
+    };
+    static const uint8_t above_ctx[N_BS_SIZES] = {
+        0x0, 0x0, 0x8, 0x8, 0x8, 0xc, 0xc, 0xc, 0xe, 0xe, 0xe, 0xf, 0xf
+    };
+    static const uint8_t max_tx_for_bl_bp[N_BS_SIZES] = {
+        TX_32X32, TX_32X32, TX_32X32, TX_32X32, TX_16X16, TX_16X16,
+        TX_16X16, TX_8X8,   TX_8X8,   TX_8X8,   TX_4X4,   TX_4X4,  TX_4X4
+    };
+    int row = b->row, col = b->col, row7 = b->row7;
+    enum TxfmMode max_tx = max_tx_for_bl_bp[b->bs];
+    int w4 = FFMIN(s->cols - col, bwh_tab[1][b->bs][0]);
+    int h4 = FFMIN(s->rows - row, bwh_tab[1][b->bs][1]);
+    int have_a = row > 0, have_l = col > s->tiling.tile_col_start;
+    int y;
+
+    if (!s->segmentation.enabled) {
+        b->seg_id = 0;
+    } else if (s->keyframe || s->intraonly) {
+        b->seg_id = s->segmentation.update_map ?
+                    vp8_rac_get_tree(&s->c, ff_vp9_segmentation_tree, s->prob.seg) : 0;
+    } else if (!s->segmentation.update_map ||
+               (s->segmentation.temporal &&
+                vp56_rac_get_prob_branchy(&s->c,
+                                          s->prob.segpred[s->above_segpred_ctx[col] +
+                                                          s->left_segpred_ctx[row7]]))) {
+        int pred = 8, x;
+
+        for (y = 0; y < h4; y++)
+            for (x = 0; x < w4; x++)
+                pred = FFMIN(pred,
+                             s->segmentation_map[(y + row) * 8 * s->sb_cols + x + col]);
+        b->seg_id = pred;
+
+        memset(&s->above_segpred_ctx[col], 1, w4);
+        memset(&s->left_segpred_ctx[row7], 1, h4);
+    } else {
+        b->seg_id = vp8_rac_get_tree(&s->c, ff_vp9_segmentation_tree,
+                                     s->prob.seg);
+
+        memset(&s->above_segpred_ctx[col], 0, w4);
+        memset(&s->left_segpred_ctx[row7], 0, h4);
+    }
+    if ((s->segmentation.enabled && s->segmentation.update_map) || s->keyframe) {
+        for (y = 0; y < h4; y++)
+            memset(&s->segmentation_map[(y + row) * 8 * s->sb_cols + col],
+                   b->seg_id, w4);
+    }
+
+    b->skip = s->segmentation.enabled &&
+              s->segmentation.feat[b->seg_id].skip_enabled;
+    if (!b->skip) {
+        int c = s->left_skip_ctx[row7] + s->above_skip_ctx[col];
+        b->skip = vp56_rac_get_prob(&s->c, s->prob.p.skip[c]);
+        s->counts.skip[c][b->skip]++;
+    }
+
+    if (s->keyframe || s->intraonly) {
+        b->intra = 1;
+    } else if (s->segmentation.feat[b->seg_id].ref_enabled) {
+        b->intra = !s->segmentation.feat[b->seg_id].ref_val;
+    } else {
+        int c, bit;
+
+        if (have_a && have_l) {
+            c  = s->above_intra_ctx[col] + s->left_intra_ctx[row7];
+            c += (c == 2);
+        } else {
+            c = have_a ? 2 * s->above_intra_ctx[col] :
+                have_l ? 2 * s->left_intra_ctx[row7] : 0;
+        }
+        bit = vp56_rac_get_prob(&s->c, s->prob.p.intra[c]);
+        s->counts.intra[c][bit]++;
+        b->intra = !bit;
+    }
+
+    if ((b->intra || !b->skip) && s->txfmmode == TX_SWITCHABLE) {
+        int c;
+        if (have_a) {
+            if (have_l) {
+                c = (s->above_skip_ctx[col] ? max_tx :
+                     s->above_txfm_ctx[col]) +
+                    (s->left_skip_ctx[row7] ? max_tx :
+                     s->left_txfm_ctx[row7]) > max_tx;
+            } else {
+                c = s->above_skip_ctx[col] ? 1 :
+                    (s->above_txfm_ctx[col] * 2 > max_tx);
+            }
+        } else if (have_l) {
+            c = s->left_skip_ctx[row7] ? 1 :
+                (s->left_txfm_ctx[row7] * 2 > max_tx);
+        } else {
+            c = 1;
+        }
+        switch (max_tx) {
+        case TX_32X32:
+            b->tx = vp56_rac_get_prob(&s->c, s->prob.p.tx32p[c][0]);
+            if (b->tx) {
+                b->tx += vp56_rac_get_prob(&s->c, s->prob.p.tx32p[c][1]);
+                if (b->tx == 2)
+                    b->tx += vp56_rac_get_prob(&s->c, s->prob.p.tx32p[c][2]);
+            }
+            s->counts.tx32p[c][b->tx]++;
+            break;
+        case TX_16X16:
+            b->tx = vp56_rac_get_prob(&s->c, s->prob.p.tx16p[c][0]);
+            if (b->tx)
+                b->tx += vp56_rac_get_prob(&s->c, s->prob.p.tx16p[c][1]);
+            s->counts.tx16p[c][b->tx]++;
+            break;
+        case TX_8X8:
+            b->tx = vp56_rac_get_prob(&s->c, s->prob.p.tx8p[c]);
+            s->counts.tx8p[c][b->tx]++;
+            break;
+        case TX_4X4:
+            b->tx = TX_4X4;
+            break;
+        }
+    } else {
+        b->tx = FFMIN(max_tx, s->txfmmode);
+    }
+
+    if (s->keyframe || s->intraonly) {
+        uint8_t *a = &s->above_mode_ctx[col * 2];
+        uint8_t *l = &s->left_mode_ctx[(row7) << 1];
+
+        b->comp = 0;
+        if (b->bs > BS_8x8) {
+            // FIXME the memory storage intermediates here aren't really
+            // necessary, they're just there to make the code slightly
+            // simpler for now
+            b->mode[0] =
+            a[0]       = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                          ff_vp9_default_kf_ymode_probs[a[0]][l[0]]);
+            if (b->bs != BS_8x4) {
+                b->mode[1] = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                              ff_vp9_default_kf_ymode_probs[a[1]][b->mode[0]]);
+                l[0]       =
+                a[1]       = b->mode[1];
+            } else {
+                l[0]       =
+                a[1]       =
+                b->mode[1] = b->mode[0];
+            }
+            if (b->bs != BS_4x8) {
+                b->mode[2] =
+                a[0]       = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                              ff_vp9_default_kf_ymode_probs[a[0]][l[1]]);
+                if (b->bs != BS_8x4) {
+                    b->mode[3] = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                                  ff_vp9_default_kf_ymode_probs[a[1]][b->mode[2]]);
+                    l[1]       =
+                    a[1]       = b->mode[3];
+                } else {
+                    l[1]       =
+                    a[1]       =
+                    b->mode[3] = b->mode[2];
+                }
+            } else {
+                b->mode[2] = b->mode[0];
+                l[1]       =
+                a[1]       =
+                b->mode[3] = b->mode[1];
+            }
+        } else {
+            b->mode[0] = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                          ff_vp9_default_kf_ymode_probs[*a][*l]);
+            b->mode[3] =
+            b->mode[2] =
+            b->mode[1] = b->mode[0];
+            // FIXME this can probably be optimized
+            memset(a, b->mode[0], bwh_tab[0][b->bs][0]);
+            memset(l, b->mode[0], bwh_tab[0][b->bs][1]);
+        }
+        b->uvmode = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                     ff_vp9_default_kf_uvmode_probs[b->mode[3]]);
+    } else if (b->intra) {
+        b->comp = 0;
+        if (b->bs > BS_8x8) {
+            b->mode[0] = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                          s->prob.p.y_mode[0]);
+            s->counts.y_mode[0][b->mode[0]]++;
+            if (b->bs != BS_8x4) {
+                b->mode[1] = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                              s->prob.p.y_mode[0]);
+                s->counts.y_mode[0][b->mode[1]]++;
+            } else {
+                b->mode[1] = b->mode[0];
+            }
+            if (b->bs != BS_4x8) {
+                b->mode[2] = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                              s->prob.p.y_mode[0]);
+                s->counts.y_mode[0][b->mode[2]]++;
+                if (b->bs != BS_8x4) {
+                    b->mode[3] = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                                  s->prob.p.y_mode[0]);
+                    s->counts.y_mode[0][b->mode[3]]++;
+                } else {
+                    b->mode[3] = b->mode[2];
+                }
+            } else {
+                b->mode[2] = b->mode[0];
+                b->mode[3] = b->mode[1];
+            }
+        } else {
+            static const uint8_t size_group[10] = {
+                3, 3, 3, 3, 2, 2, 2, 1, 1, 1
+            };
+            int sz = size_group[b->bs];
+
+            b->mode[0] = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                          s->prob.p.y_mode[sz]);
+            b->mode[1] =
+            b->mode[2] =
+            b->mode[3] = b->mode[0];
+            s->counts.y_mode[sz][b->mode[3]]++;
+        }
+        b->uvmode = vp8_rac_get_tree(&s->c, ff_vp9_intramode_tree,
+                                     s->prob.p.uv_mode[b->mode[3]]);
+        s->counts.uv_mode[b->mode[3]][b->uvmode]++;
+    } else {
+        static const uint8_t inter_mode_ctx_lut[14][14] = {
+            { 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5 },
+            { 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5 },
+            { 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5 },
+            { 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5 },
+            { 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5 },
+            { 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5 },
+            { 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5 },
+            { 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5 },
+            { 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5 },
+            { 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5 },
+            { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 2, 2, 1, 3 },
+            { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 2, 2, 1, 3 },
+            { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 1, 1, 0, 3 },
+            { 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 3, 3, 3, 4 },
+        };
+
+        if (s->segmentation.feat[b->seg_id].ref_enabled) {
+            av_assert2(s->segmentation.feat[b->seg_id].ref_val != 0);
+            b->comp   = 0;
+            b->ref[0] = s->segmentation.feat[b->seg_id].ref_val - 1;
+        } else {
+            // read comp_pred flag
+            if (s->comppredmode != PRED_SWITCHABLE) {
+                b->comp = s->comppredmode == PRED_COMPREF;
+            } else {
+                int c;
+
+                // FIXME add intra as ref=0xff (or -1) to make these easier?
+                if (have_a) {
+                    if (have_l) {
+                        if (s->above_comp_ctx[col] && s->left_comp_ctx[row7]) {
+                            c = 4;
+                        } else if (s->above_comp_ctx[col]) {
+                            c = 2 + (s->left_intra_ctx[row7] ||
+                                     s->left_ref_ctx[row7] == s->fixcompref);
+                        } else if (s->left_comp_ctx[row7]) {
+                            c = 2 + (s->above_intra_ctx[col] ||
+                                     s->above_ref_ctx[col] == s->fixcompref);
+                        } else {
+                            c = (!s->above_intra_ctx[col] &&
+                                 s->above_ref_ctx[col] == s->fixcompref) ^
+                                (!s->left_intra_ctx[row7] &&
+                                 s->left_ref_ctx[row & 7] == s->fixcompref);
+                        }
+                    } else {
+                        c = s->above_comp_ctx[col] ? 3 :
+                            (!s->above_intra_ctx[col] && s->above_ref_ctx[col] == s->fixcompref);
+                    }
+                } else if (have_l) {
+                    c = s->left_comp_ctx[row7] ? 3 :
+                        (!s->left_intra_ctx[row7] && s->left_ref_ctx[row7] == s->fixcompref);
+                } else {
+                    c = 1;
+                }
+                b->comp = vp56_rac_get_prob(&s->c, s->prob.p.comp[c]);
+                s->counts.comp[c][b->comp]++;
+            }
+
+            // read actual references
+            // FIXME probably cache a few variables here to prevent repetitive
+            // memory accesses below
+            if (b->comp) { /* two references */
+                int fix_idx = s->signbias[s->fixcompref], var_idx = !fix_idx, c, bit;
+
+                b->ref[fix_idx] = s->fixcompref;
+                // FIXME can this codeblob be replaced by some sort of LUT?
+                if (have_a) {
+                    if (have_l) {
+                        if (s->above_intra_ctx[col]) {
+                            if (s->left_intra_ctx[row7]) {
+                                c = 2;
+                            } else {
+                                c = 1 + 2 * (s->left_ref_ctx[row7] != s->varcompref[1]);
+                            }
+                        } else if (s->left_intra_ctx[row7]) {
+                            c = 1 + 2 * (s->above_ref_ctx[col] != s->varcompref[1]);
+                        } else {
+                            int refl = s->left_ref_ctx[row7], refa = s->above_ref_ctx[col];
+
+                            if (refl == refa && refa == s->varcompref[1]) {
+                                c = 0;
+                            } else if (!s->left_comp_ctx[row7] && !s->above_comp_ctx[col]) {
+                                if ((refa == s->fixcompref && refl == s->varcompref[0]) ||
+                                    (refl == s->fixcompref && refa == s->varcompref[0])) {
+                                    c = 4;
+                                } else {
+                                    c = (refa == refl) ? 3 : 1;
+                                }
+                            } else if (!s->left_comp_ctx[row7]) {
+                                if (refa == s->varcompref[1] && refl != s->varcompref[1]) {
+                                    c = 1;
+                                } else {
+                                    c = (refl == s->varcompref[1] &&
+                                         refa != s->varcompref[1]) ? 2 : 4;
+                                }
+                            } else if (!s->above_comp_ctx[col]) {
+                                if (refl == s->varcompref[1] && refa != s->varcompref[1]) {
+                                    c = 1;
+                                } else {
+                                    c = (refa == s->varcompref[1] &&
+                                         refl != s->varcompref[1]) ? 2 : 4;
+                                }
+                            } else {
+                                c = (refl == refa) ? 4 : 2;
+                            }
+                        }
+                    } else {
+                        if (s->above_intra_ctx[col]) {
+                            c = 2;
+                        } else if (s->above_comp_ctx[col]) {
+                            c = 4 * (s->above_ref_ctx[col] != s->varcompref[1]);
+                        } else {
+                            c = 3 * (s->above_ref_ctx[col] != s->varcompref[1]);
+                        }
+                    }
+                } else if (have_l) {
+                    if (s->left_intra_ctx[row7]) {
+                        c = 2;
+                    } else if (s->left_comp_ctx[row7]) {
+                        c = 4 * (s->left_ref_ctx[row7] != s->varcompref[1]);
+                    } else {
+                        c = 3 * (s->left_ref_ctx[row7] != s->varcompref[1]);
+                    }
+                } else {
+                    c = 2;
+                }
+                bit = vp56_rac_get_prob(&s->c, s->prob.p.comp_ref[c]);
+                b->ref[var_idx] = s->varcompref[bit];
+                s->counts.comp_ref[c][bit]++;
+            } else { /* single reference */
+                int bit, c;
+
+                if (have_a && !s->above_intra_ctx[col]) {
+                    if (have_l && !s->left_intra_ctx[row7]) {
+                        if (s->left_comp_ctx[row7]) {
+                            if (s->above_comp_ctx[col]) {
+                                c = 1 + (!s->fixcompref || !s->left_ref_ctx[row7] ||
+                                         !s->above_ref_ctx[col]);
+                            } else {
+                                c = (3 * !s->above_ref_ctx[col]) +
+                                    (!s->fixcompref || !s->left_ref_ctx[row7]);
+                            }
+                        } else if (s->above_comp_ctx[col]) {
+                            c = (3 * !s->left_ref_ctx[row7]) +
+                                (!s->fixcompref || !s->above_ref_ctx[col]);
+                        } else {
+                            c = 2 * !s->left_ref_ctx[row7] + 2 * !s->above_ref_ctx[col];
+                        }
+                    } else if (s->above_intra_ctx[col]) {
+                        c = 2;
+                    } else if (s->above_comp_ctx[col]) {
+                        c = 1 + (!s->fixcompref || !s->above_ref_ctx[col]);
+                    } else {
+                        c = 4 * (!s->above_ref_ctx[col]);
+                    }
+                } else if (have_l && !s->left_intra_ctx[row7]) {
+                    if (s->left_intra_ctx[row7]) {
+                        c = 2;
+                    } else if (s->left_comp_ctx[row7]) {
+                        c = 1 + (!s->fixcompref || !s->left_ref_ctx[row7]);
+                    } else {
+                        c = 4 * (!s->left_ref_ctx[row7]);
+                    }
+                } else {
+                    c = 2;
+                }
+                bit = vp56_rac_get_prob(&s->c, s->prob.p.single_ref[c][0]);
+                s->counts.single_ref[c][0][bit]++;
+                if (!bit) {
+                    b->ref[0] = 0;
+                } else {
+                    // FIXME can this codeblob be replaced by some sort of LUT?
+                    if (have_a) {
+                        if (have_l) {
+                            if (s->left_intra_ctx[row7]) {
+                                if (s->above_intra_ctx[col]) {
+                                    c = 2;
+                                } else if (s->above_comp_ctx[col]) {
+                                    c = 1 + 2 * (s->fixcompref == 1 ||
+                                                 s->above_ref_ctx[col] == 1);
+                                } else if (!s->above_ref_ctx[col]) {
+                                    c = 3;
+                                } else {
+                                    c = 4 * (s->above_ref_ctx[col] == 1);
+                                }
+                            } else if (s->above_intra_ctx[col]) {
+                                if (s->left_intra_ctx[row7]) {
+                                    c = 2;
+                                } else if (s->left_comp_ctx[row7]) {
+                                    c = 1 + 2 * (s->fixcompref == 1 ||
+                                                 s->left_ref_ctx[row7] == 1);
+                                } else if (!s->left_ref_ctx[row7]) {
+                                    c = 3;
+                                } else {
+                                    c = 4 * (s->left_ref_ctx[row7] == 1);
+                                }
+                            } else if (s->above_comp_ctx[col]) {
+                                if (s->left_comp_ctx[row7]) {
+                                    if (s->left_ref_ctx[row7] == s->above_ref_ctx[col]) {
+                                        c = 3 * (s->fixcompref == 1 ||
+                                                 s->left_ref_ctx[row7] == 1);
+                                    } else {
+                                        c = 2;
+                                    }
+                                } else if (!s->left_ref_ctx[row7]) {
+                                    c = 1 + 2 * (s->fixcompref == 1 ||
+                                                 s->above_ref_ctx[col] == 1);
+                                } else {
+                                    c = 3 * (s->left_ref_ctx[row7] == 1) +
+                                        (s->fixcompref == 1 || s->above_ref_ctx[col] == 1);
+                                }
+                            } else if (s->left_comp_ctx[row7]) {
+                                if (!s->above_ref_ctx[col]) {
+                                    c = 1 + 2 * (s->fixcompref == 1 ||
+                                                 s->left_ref_ctx[row7] == 1);
+                                } else {
+                                    c = 3 * (s->above_ref_ctx[col] == 1) +
+                                        (s->fixcompref == 1 || s->left_ref_ctx[row7] == 1);
+                                }
+                            } else if (!s->above_ref_ctx[col]) {
+                                if (!s->left_ref_ctx[row7]) {
+                                    c = 3;
+                                } else {
+                                    c = 4 * (s->left_ref_ctx[row7] == 1);
+                                }
+                            } else if (!s->left_ref_ctx[row7]) {
+                                c = 4 * (s->above_ref_ctx[col] == 1);
+                            } else {
+                                c = 2 * (s->left_ref_ctx[row7] == 1) +
+                                    2 * (s->above_ref_ctx[col] == 1);
+                            }
+                        } else {
+                            if (s->above_intra_ctx[col] ||
+                                (!s->above_comp_ctx[col] && !s->above_ref_ctx[col])) {
+                                c = 2;
+                            } else if (s->above_comp_ctx[col]) {
+                                c = 3 * (s->fixcompref == 1 || s->above_ref_ctx[col] == 1);
+                            } else {
+                                c = 4 * (s->above_ref_ctx[col] == 1);
+                            }
+                        }
+                    } else if (have_l) {
+                        if (s->left_intra_ctx[row7] ||
+                            (!s->left_comp_ctx[row7] && !s->left_ref_ctx[row7])) {
+                            c = 2;
+                        } else if (s->left_comp_ctx[row7]) {
+                            c = 3 * (s->fixcompref == 1 || s->left_ref_ctx[row7] == 1);
+                        } else {
+                            c = 4 * (s->left_ref_ctx[row7] == 1);
+                        }
+                    } else {
+                        c = 2;
+                    }
+                    bit = vp56_rac_get_prob(&s->c, s->prob.p.single_ref[c][1]);
+                    s->counts.single_ref[c][1][bit]++;
+                    b->ref[0] = 1 + bit;
+                }
+            }
+        }
+
+        if (b->bs <= BS_8x8) {
+            if (s->segmentation.feat[b->seg_id].skip_enabled) {
+                b->mode[0] =
+                b->mode[1] =
+                b->mode[2] =
+                b->mode[3] = ZEROMV;
+            } else {
+                static const uint8_t off[10] = {
+                    3, 0, 0, 1, 0, 0, 0, 0, 0, 0
+                };
+
+                // FIXME this needs to use the LUT tables from find_ref_mvs
+                // because not all are -1,0/0,-1
+                int c = inter_mode_ctx_lut[s->above_mode_ctx[col + off[b->bs]]]
+                                          [s->left_mode_ctx[row7 + off[b->bs]]];
+
+                b->mode[0] = vp8_rac_get_tree(&s->c, ff_vp9_inter_mode_tree,
+                                              s->prob.p.mv_mode[c]);
+                b->mode[1] =
+                b->mode[2] =
+                b->mode[3] = b->mode[0];
+                s->counts.mv_mode[c][b->mode[0] - 10]++;
+            }
+        }
+
+        if (s->filtermode == FILTER_SWITCHABLE) {
+            int c;
+
+            if (have_a && s->above_mode_ctx[col] >= NEARESTMV) {
+                if (have_l && s->left_mode_ctx[row7] >= NEARESTMV) {
+                    c = s->above_filter_ctx[col] == s->left_filter_ctx[row7] ?
+                        s->left_filter_ctx[row7] : 3;
+                } else {
+                    c = s->above_filter_ctx[col];
+                }
+            } else if (have_l && s->left_mode_ctx[row7] >= NEARESTMV) {
+                c = s->left_filter_ctx[row7];
+            } else {
+                c = 3;
+            }
+
+            b->filter = vp8_rac_get_tree(&s->c, ff_vp9_filter_tree,
+                                         s->prob.p.filter[c]);
+            s->counts.filter[c][b->filter]++;
+        } else {
+            b->filter = s->filtermode;
+        }
+
+        if (b->bs > BS_8x8) {
+            int c = inter_mode_ctx_lut[s->above_mode_ctx[col]][s->left_mode_ctx[row7]];
+
+            b->mode[0] = vp8_rac_get_tree(&s->c, ff_vp9_inter_mode_tree,
+                                          s->prob.p.mv_mode[c]);
+            s->counts.mv_mode[c][b->mode[0] - 10]++;
+            ff_vp9_fill_mv(s, b->mv[0], b->mode[0], 0);
+
+            if (b->bs != BS_8x4) {
+                b->mode[1] = vp8_rac_get_tree(&s->c, ff_vp9_inter_mode_tree,
+                                              s->prob.p.mv_mode[c]);
+                s->counts.mv_mode[c][b->mode[1] - 10]++;
+                ff_vp9_fill_mv(s, b->mv[1], b->mode[1], 1);
+            } else {
+                b->mode[1] = b->mode[0];
+                AV_COPY32(&b->mv[1][0], &b->mv[0][0]);
+                AV_COPY32(&b->mv[1][1], &b->mv[0][1]);
+            }
+
+            if (b->bs != BS_4x8) {
+                b->mode[2] = vp8_rac_get_tree(&s->c, ff_vp9_inter_mode_tree,
+                                              s->prob.p.mv_mode[c]);
+                s->counts.mv_mode[c][b->mode[2] - 10]++;
+                ff_vp9_fill_mv(s, b->mv[2], b->mode[2], 2);
+
+                if (b->bs != BS_8x4) {
+                    b->mode[3] = vp8_rac_get_tree(&s->c, ff_vp9_inter_mode_tree,
+                                                  s->prob.p.mv_mode[c]);
+                    s->counts.mv_mode[c][b->mode[3] - 10]++;
+                    ff_vp9_fill_mv(s, b->mv[3], b->mode[3], 3);
+                } else {
+                    b->mode[3] = b->mode[2];
+                    AV_COPY32(&b->mv[3][0], &b->mv[2][0]);
+                    AV_COPY32(&b->mv[3][1], &b->mv[2][1]);
+                }
+            } else {
+                b->mode[2] = b->mode[0];
+                AV_COPY32(&b->mv[2][0], &b->mv[0][0]);
+                AV_COPY32(&b->mv[2][1], &b->mv[0][1]);
+                b->mode[3] = b->mode[1];
+                AV_COPY32(&b->mv[3][0], &b->mv[1][0]);
+                AV_COPY32(&b->mv[3][1], &b->mv[1][1]);
+            }
+        } else {
+            ff_vp9_fill_mv(s, b->mv[0], b->mode[0], -1);
+            AV_COPY32(&b->mv[1][0], &b->mv[0][0]);
+            AV_COPY32(&b->mv[2][0], &b->mv[0][0]);
+            AV_COPY32(&b->mv[3][0], &b->mv[0][0]);
+            AV_COPY32(&b->mv[1][1], &b->mv[0][1]);
+            AV_COPY32(&b->mv[2][1], &b->mv[0][1]);
+            AV_COPY32(&b->mv[3][1], &b->mv[0][1]);
+        }
+    }
+
+    // FIXME this can probably be optimized
+    memset(&s->above_skip_ctx[col], b->skip, w4);
+    memset(&s->left_skip_ctx[row7], b->skip, h4);
+    memset(&s->above_txfm_ctx[col], b->tx, w4);
+    memset(&s->left_txfm_ctx[row7], b->tx, h4);
+    memset(&s->above_partition_ctx[col], above_ctx[b->bs], w4);
+    memset(&s->left_partition_ctx[row7], left_ctx[b->bs], h4);
+    if (!s->keyframe && !s->intraonly) {
+        memset(&s->above_intra_ctx[col], b->intra, w4);
+        memset(&s->left_intra_ctx[row7], b->intra, h4);
+        memset(&s->above_comp_ctx[col], b->comp, w4);
+        memset(&s->left_comp_ctx[row7], b->comp, h4);
+        memset(&s->above_mode_ctx[col], b->mode[3], w4);
+        memset(&s->left_mode_ctx[row7], b->mode[3], h4);
+        if (s->filtermode == FILTER_SWITCHABLE && !b->intra) {
+            memset(&s->above_filter_ctx[col], b->filter, w4);
+            memset(&s->left_filter_ctx[row7], b->filter, h4);
+            b->filter = ff_vp9_filter_lut[b->filter];
+        }
+        if (b->bs > BS_8x8) {
+            int mv0 = AV_RN32A(&b->mv[3][0]), mv1 = AV_RN32A(&b->mv[3][1]);
+
+            AV_COPY32(&s->left_mv_ctx[row7 * 2 + 0][0], &b->mv[1][0]);
+            AV_COPY32(&s->left_mv_ctx[row7 * 2 + 0][1], &b->mv[1][1]);
+            AV_WN32A(&s->left_mv_ctx[row7 * 2 + 1][0], mv0);
+            AV_WN32A(&s->left_mv_ctx[row7 * 2 + 1][1], mv1);
+            AV_COPY32(&s->above_mv_ctx[col * 2 + 0][0], &b->mv[2][0]);
+            AV_COPY32(&s->above_mv_ctx[col * 2 + 0][1], &b->mv[2][1]);
+            AV_WN32A(&s->above_mv_ctx[col * 2 + 1][0], mv0);
+            AV_WN32A(&s->above_mv_ctx[col * 2 + 1][1], mv1);
+        } else {
+            int n, mv0 = AV_RN32A(&b->mv[3][0]), mv1 = AV_RN32A(&b->mv[3][1]);
+
+            for (n = 0; n < w4 * 2; n++) {
+                AV_WN32A(&s->above_mv_ctx[col * 2 + n][0], mv0);
+                AV_WN32A(&s->above_mv_ctx[col * 2 + n][1], mv1);
+            }
+            for (n = 0; n < h4 * 2; n++) {
+                AV_WN32A(&s->left_mv_ctx[row7 * 2 + n][0], mv0);
+                AV_WN32A(&s->left_mv_ctx[row7 * 2 + n][1], mv1);
+            }
+        }
+
+        if (!b->intra) { // FIXME write 0xff or -1 if intra, so we can use this
+                         // as a direct check in above branches
+            int vref = b->ref[b->comp ? s->signbias[s->varcompref[0]] : 0];
+
+            memset(&s->above_ref_ctx[col], vref, w4);
+            memset(&s->left_ref_ctx[row7], vref, h4);
+        }
+    }
+
+    // FIXME kinda ugly
+    for (y = 0; y < h4; y++) {
+        int x, o = (row + y) * s->sb_cols * 8 + col;
+
+        if (b->intra) {
+            for (x = 0; x < w4; x++) {
+                s->mv[0][o + x].ref[0] =
+                s->mv[0][o + x].ref[1] = -1;
+            }
+        } else if (b->comp) {
+            for (x = 0; x < w4; x++) {
+                s->mv[0][o + x].ref[0] = b->ref[0];
+                s->mv[0][o + x].ref[1] = b->ref[1];
+                AV_COPY32(&s->mv[0][o + x].mv[0], &b->mv[3][0]);
+                AV_COPY32(&s->mv[0][o + x].mv[1], &b->mv[3][1]);
+            }
+        } else {
+            for (x = 0; x < w4; x++) {
+                s->mv[0][o + x].ref[0] = b->ref[0];
+                s->mv[0][o + x].ref[1] = -1;
+                AV_COPY32(&s->mv[0][o + x].mv[0], &b->mv[3][0]);
+            }
+        }
+    }
+}
+
+// FIXME remove tx argument, and merge cnt/eob arguments?
+static int decode_block_coeffs(VP56RangeCoder *c, int16_t *coef, int n_coeffs,
+                               enum TxfmMode tx, unsigned (*cnt)[6][3],
+                               unsigned (*eob)[6][2], uint8_t(*p)[6][11],
+                               int nnz, const int16_t *scan,
+                               const int16_t(*nb)[2],
+                               const int16_t *band_counts, const int16_t *qmul)
+{
+    int i = 0, band = 0, band_left = band_counts[band];
+    uint8_t *tp = p[0][nnz];
+    uint8_t cache[1024];
+
+    do {
+        int val, rc;
+
+        val = vp56_rac_get_prob_branchy(c, tp[0]); // eob
+        eob[band][nnz][val]++;
+        if (!val)
+            break;
+
+skip_eob:
+        if (!vp56_rac_get_prob_branchy(c, tp[1])) { // zero
+            cnt[band][nnz][0]++;
+            if (!--band_left)
+                band_left = band_counts[++band];
+            cache[scan[i]] = 0;
+            nnz            = (1 + cache[nb[i][0]] + cache[nb[i][1]]) >> 1;
+            tp             = p[band][nnz];
+            if (++i == n_coeffs)
+                break;  //invalid input; blocks should end with EOB
+            goto skip_eob;
+        }
+
+        rc = scan[i];
+        if (!vp56_rac_get_prob_branchy(c, tp[2])) { // one
+            cnt[band][nnz][1]++;
+            val       = 1;
+            cache[rc] = 1;
+        } else {
+            // fill in p[3-10] (model fill) - only once per frame for each pos
+            if (!tp[3])
+                memcpy(&tp[3], ff_vp9_model_pareto8[tp[2]], 8);
+
+            cnt[band][nnz][2]++;
+            if (!vp56_rac_get_prob_branchy(c, tp[3])) { // 2, 3, 4
+                if (!vp56_rac_get_prob_branchy(c, tp[4])) {
+                    cache[rc] = val = 2;
+                } else {
+                    val       = 3 + vp56_rac_get_prob(c, tp[5]);
+                    cache[rc] = 3;
+                }
+            } else if (!vp56_rac_get_prob_branchy(c, tp[6])) { // cat1/2
+                cache[rc] = 4;
+                if (!vp56_rac_get_prob_branchy(c, tp[7])) {
+                    val  =  vp56_rac_get_prob(c, 159) + 5;
+                } else {
+                    val  = (vp56_rac_get_prob(c, 165) << 1) + 7;
+                    val +=  vp56_rac_get_prob(c, 145);
+                }
+            } else { // cat 3-6
+                cache[rc] = 5;
+                if (!vp56_rac_get_prob_branchy(c, tp[8])) {
+                    if (!vp56_rac_get_prob_branchy(c, tp[9])) {
+                        val  = (vp56_rac_get_prob(c, 173) << 2) + 11;
+                        val += (vp56_rac_get_prob(c, 148) << 1);
+                        val +=  vp56_rac_get_prob(c, 140);
+                    } else {
+                        val  = (vp56_rac_get_prob(c, 176) << 3) + 19;
+                        val += (vp56_rac_get_prob(c, 155) << 2);
+                        val += (vp56_rac_get_prob(c, 140) << 1);
+                        val +=  vp56_rac_get_prob(c, 135);
+                    }
+                } else if (!vp56_rac_get_prob_branchy(c, tp[10])) {
+                    val  = (vp56_rac_get_prob(c, 180) << 4) + 35;
+                    val += (vp56_rac_get_prob(c, 157) << 3);
+                    val += (vp56_rac_get_prob(c, 141) << 2);
+                    val += (vp56_rac_get_prob(c, 134) << 1);
+                    val +=  vp56_rac_get_prob(c, 130);
+                } else {
+                    val  = (vp56_rac_get_prob(c, 254) << 13) + 67;
+                    val += (vp56_rac_get_prob(c, 254) << 12);
+                    val += (vp56_rac_get_prob(c, 254) << 11);
+                    val += (vp56_rac_get_prob(c, 252) << 10);
+                    val += (vp56_rac_get_prob(c, 249) << 9);
+                    val += (vp56_rac_get_prob(c, 243) << 8);
+                    val += (vp56_rac_get_prob(c, 230) << 7);
+                    val += (vp56_rac_get_prob(c, 196) << 6);
+                    val += (vp56_rac_get_prob(c, 177) << 5);
+                    val += (vp56_rac_get_prob(c, 153) << 4);
+                    val += (vp56_rac_get_prob(c, 140) << 3);
+                    val += (vp56_rac_get_prob(c, 133) << 2);
+                    val += (vp56_rac_get_prob(c, 130) << 1);
+                    val +=  vp56_rac_get_prob(c, 129);
+                }
+            }
+        }
+        if (!--band_left)
+            band_left = band_counts[++band];
+        if (tx == TX_32X32) // FIXME slow
+            coef[rc] = ((vp8_rac_get(c) ? -val : val) * qmul[!!i]) / 2;
+        else
+            coef[rc] = (vp8_rac_get(c) ? -val : val) * qmul[!!i];
+        nnz = (1 + cache[nb[i][0]] + cache[nb[i][1]]) >> 1;
+        tp  = p[band][nnz];
+    } while (++i < n_coeffs);
+
+    return i;
+}
+
+static int decode_coeffs(AVCodecContext *avctx)
+{
+    VP9Context *s = avctx->priv_data;
+    VP9Block *const b = &s->b;
+    int row = b->row, col = b->col;
+    uint8_t (*p)[6][11] = s->prob.coef[b->tx][0 /* y */][!b->intra];
+    unsigned (*c)[6][3] = s->counts.coef[b->tx][0 /* y */][!b->intra];
+    unsigned (*e)[6][2] = s->counts.eob[b->tx][0 /* y */][!b->intra];
+    int w4 = bwh_tab[1][b->bs][0] << 1, h4 = bwh_tab[1][b->bs][1] << 1;
+    int end_x = FFMIN(2 * (s->cols - col), w4);
+    int end_y = FFMIN(2 * (s->rows - row), h4);
+    int n, pl, x, y, step1d = 1 << b->tx, step = 1 << (b->tx * 2);
+    int uvstep1d = 1 << b->uvtx, uvstep = 1 << (b->uvtx * 2), ret;
+    int16_t (*qmul)[2] = s->segmentation.feat[b->seg_id].qmul;
+    int tx = 4 * s->lossless + b->tx;
+    const int16_t **yscans = ff_vp9_scans[tx];
+    const int16_t (**ynbs)[2] = ff_vp9_scans_nb[tx];
+    const int16_t *uvscan = ff_vp9_scans[b->uvtx][DCT_DCT];
+    const int16_t (*uvnb)[2] = ff_vp9_scans_nb[b->uvtx][DCT_DCT];
+    uint8_t *a = &s->above_y_nnz_ctx[col * 2];
+    uint8_t *l = &s->left_y_nnz_ctx[(row & 7) << 1];
+    static const int16_t band_counts[4][8] = {
+        { 1, 2, 3, 4,  3,   16 - 13, 0 },
+        { 1, 2, 3, 4, 11,   64 - 21, 0 },
+        { 1, 2, 3, 4, 11,  256 - 21, 0 },
+        { 1, 2, 3, 4, 11, 1024 - 21, 0 },
+    };
+    const int16_t *y_band_counts  = band_counts[b->tx];
+    const int16_t *uv_band_counts = band_counts[b->uvtx];
+
+    /* y tokens */
+    if (b->tx > TX_4X4) { // FIXME slow
+        for (y = 0; y < end_y; y += step1d)
+            for (x = 1; x < step1d; x++)
+                l[y] |= l[y + x];
+        for (x = 0; x < end_x; x += step1d)
+            for (y = 1; y < step1d; y++)
+                a[x] |= a[x + y];
+    }
+    for (n = 0, y = 0; y < end_y; y += step1d) {
+        for (x = 0; x < end_x; x += step1d, n += step) {
+            enum TxfmType txtp = ff_vp9_intra_txfm_type[b->mode[b->tx == TX_4X4 &&
+                                                                b->bs > BS_8x8 ?
+                                                                n : 0]];
+            int nnz = a[x] + l[y];
+            if ((ret = decode_block_coeffs(&s->c, s->block + 16 * n, 16 * step,
+                                           b->tx, c, e, p, nnz, yscans[txtp],
+                                           ynbs[txtp], y_band_counts,
+                                           qmul[0])) < 0)
+                return ret;
+            a[x] = l[y] = !!ret;
+            if (b->tx > TX_8X8)
+                AV_WN16A(&s->eob[n], ret);
+            else
+                s->eob[n] = ret;
+        }
+    }
+    if (b->tx > TX_4X4) { // FIXME slow
+        for (y = 0; y < end_y; y += step1d)
+            memset(&l[y + 1], l[y], FFMIN(end_y - y - 1, step1d - 1));
+        for (x = 0; x < end_x; x += step1d)
+            memset(&a[x + 1], a[x], FFMIN(end_x - x - 1, step1d - 1));
+    }
+
+    p = s->prob.coef[b->uvtx][1 /* uv */][!b->intra];
+    c = s->counts.coef[b->uvtx][1 /* uv */][!b->intra];
+    e = s->counts.eob[b->uvtx][1 /* uv */][!b->intra];
+    w4    >>= 1;
+    h4    >>= 1;
+    end_x >>= 1;
+    end_y >>= 1;
+    for (pl = 0; pl < 2; pl++) {
+        a = &s->above_uv_nnz_ctx[pl][col];
+        l = &s->left_uv_nnz_ctx[pl][row & 7];
+        if (b->uvtx > TX_4X4) { // FIXME slow
+            for (y = 0; y < end_y; y += uvstep1d)
+                for (x = 1; x < uvstep1d; x++)
+                    l[y] |= l[y + x];
+            for (x = 0; x < end_x; x += uvstep1d)
+                for (y = 1; y < uvstep1d; y++)
+                    a[x] |= a[x + y];
+        }
+        for (n = 0, y = 0; y < end_y; y += uvstep1d) {
+            for (x = 0; x < end_x; x += uvstep1d, n += uvstep) {
+                int nnz = a[x] + l[y];
+                if ((ret = decode_block_coeffs(&s->c, s->uvblock[pl] + 16 * n,
+                                               16 * uvstep, b->uvtx, c, e, p,
+                                               nnz, uvscan, uvnb,
+                                               uv_band_counts, qmul[1])) < 0)
+                    return ret;
+                a[x] = l[y] = !!ret;
+                if (b->uvtx > TX_8X8)
+                    AV_WN16A(&s->uveob[pl][n], ret);
+                else
+                    s->uveob[pl][n] = ret;
+            }
+        }
+        if (b->uvtx > TX_4X4) { // FIXME slow
+            for (y = 0; y < end_y; y += uvstep1d)
+                memset(&l[y + 1], l[y], FFMIN(end_y - y - 1, uvstep1d - 1));
+            for (x = 0; x < end_x; x += uvstep1d)
+                memset(&a[x + 1], a[x], FFMIN(end_x - x - 1, uvstep1d - 1));
+        }
+    }
+
+    return 0;
+}
+
+static av_always_inline int check_intra_mode(VP9Context *s, int mode,
+                                             uint8_t **a,
+                                             uint8_t *dst_edge,
+                                             ptrdiff_t stride_edge,
+                                             uint8_t *dst_inner,
+                                             ptrdiff_t stride_inner,
+                                             uint8_t *l, int col, int x, int w,
+                                             int row, int y, enum TxfmMode tx,
+                                             int p)
+{
+    int have_top   = row > 0 || y > 0;
+    int have_left  = col > s->tiling.tile_col_start || x > 0;
+    int have_right = x < w - 1;
+    static const uint8_t mode_conv[10][2 /* have_left */][2 /* have_top */] = {
+        [VERT_PRED]            = { { DC_127_PRED,          VERT_PRED            },
+                                   { DC_127_PRED,          VERT_PRED            } },
+        [HOR_PRED]             = { { DC_129_PRED,          DC_129_PRED          },
+                                   { HOR_PRED,             HOR_PRED             } },
+        [DC_PRED]              = { { DC_128_PRED,          TOP_DC_PRED          },
+                                   { LEFT_DC_PRED,         DC_PRED              } },
+        [DIAG_DOWN_LEFT_PRED]  = { { DC_127_PRED,          DIAG_DOWN_LEFT_PRED  },
+                                   { DC_127_PRED,          DIAG_DOWN_LEFT_PRED  } },
+        [DIAG_DOWN_RIGHT_PRED] = { { DIAG_DOWN_RIGHT_PRED, DIAG_DOWN_RIGHT_PRED },
+                                   { DIAG_DOWN_RIGHT_PRED, DIAG_DOWN_RIGHT_PRED } },
+        [VERT_RIGHT_PRED]      = { { VERT_RIGHT_PRED,      VERT_RIGHT_PRED      },
+                                   { VERT_RIGHT_PRED,      VERT_RIGHT_PRED      } },
+        [HOR_DOWN_PRED]        = { { HOR_DOWN_PRED,        HOR_DOWN_PRED        },
+                                   { HOR_DOWN_PRED,        HOR_DOWN_PRED        } },
+        [VERT_LEFT_PRED]       = { { DC_127_PRED,          VERT_LEFT_PRED       },
+                                   { DC_127_PRED,          VERT_LEFT_PRED       } },
+        [HOR_UP_PRED]          = { { DC_129_PRED,          DC_129_PRED          },
+                                   { HOR_UP_PRED,          HOR_UP_PRED          } },
+        [TM_VP8_PRED]          = { { DC_129_PRED,          VERT_PRED            },
+                                   { HOR_PRED,             TM_VP8_PRED          } },
+    };
+    static const struct {
+        uint8_t needs_left:1;
+        uint8_t needs_top:1;
+        uint8_t needs_topleft:1;
+        uint8_t needs_topright:1;
+    } edges[N_INTRA_PRED_MODES] = {
+        [VERT_PRED]            = { .needs_top  = 1 },
+        [HOR_PRED]             = { .needs_left = 1 },
+        [DC_PRED]              = { .needs_top  = 1, .needs_left = 1 },
+        [DIAG_DOWN_LEFT_PRED]  = { .needs_top  = 1, .needs_topright = 1 },
+        [DIAG_DOWN_RIGHT_PRED] = { .needs_left = 1, .needs_top = 1,
+                                   .needs_topleft = 1 },
+        [VERT_RIGHT_PRED]      = { .needs_left = 1, .needs_top = 1,
+                                   .needs_topleft = 1 },
+        [HOR_DOWN_PRED]        = { .needs_left = 1, .needs_top = 1,
+                                   .needs_topleft = 1 },
+        [VERT_LEFT_PRED]       = { .needs_top  = 1, .needs_topright = 1 },
+        [HOR_UP_PRED]          = { .needs_left = 1 },
+        [TM_VP8_PRED]          = { .needs_left = 1, .needs_top = 1,
+                                   .needs_topleft = 1 },
+        [LEFT_DC_PRED]         = { .needs_left = 1 },
+        [TOP_DC_PRED]          = { .needs_top  = 1 },
+        [DC_128_PRED]          = { 0 },
+        [DC_127_PRED]          = { 0 },
+        [DC_129_PRED]          = { 0 }
+    };
+
+    av_assert2(mode >= 0 && mode < 10);
+    mode = mode_conv[mode][have_left][have_top];
+    if (edges[mode].needs_top) {
+        uint8_t *top = NULL, *topleft = NULL;
+        int n_px_need = 4 << tx, n_px_have = (((s->cols - col) << !p) - x) * 4;
+        int n_px_need_tr = 0;
+
+        if (tx == TX_4X4 && edges[mode].needs_topright && have_right)
+            n_px_need_tr = 4;
+
+        // if top of sb64-row, use s->intra_pred_data[] instead of
+        // dst[-stride] for intra prediction (it contains pre- instead of
+        // post-loopfilter data)
+        if (have_top) {
+            top = !(row & 7) && !y ?
+                  s->intra_pred_data[p] + col * (8 >> !!p) + x * 4 :
+                  y == 0 ? &dst_edge[-stride_edge] : &dst_inner[-stride_inner];
+            if (have_left)
+                topleft = !(row & 7) && !y ?
+                          s->intra_pred_data[p] + col * (8 >> !!p) + x * 4 :
+                          y == 0 || x == 0 ? &dst_edge[-stride_edge] :
+                          &dst_inner[-stride_inner];
+        }
+
+        if (have_top &&
+            (!edges[mode].needs_topleft || (have_left && top == topleft)) &&
+            (tx != TX_4X4 || !edges[mode].needs_topright || have_right) &&
+            n_px_need + n_px_need_tr <= n_px_have) {
+            *a = top;
+        } else {
+            if (have_top) {
+                if (n_px_need <= n_px_have) {
+                    memcpy(*a, top, n_px_need);
+                } else {
+                    memcpy(*a, top, n_px_have);
+                    memset(&(*a)[n_px_have], (*a)[n_px_have - 1],
+                           n_px_need - n_px_have);
+                }
+            } else {
+                memset(*a, 127, n_px_need);
+            }
+            if (edges[mode].needs_topleft) {
+                if (have_left && have_top)
+                    (*a)[-1] = topleft[-1];
+                else
+                    (*a)[-1] = have_top ? 129 : 127;
+            }
+            if (tx == TX_4X4 && edges[mode].needs_topright) {
+                if (have_top && have_right &&
+                    n_px_need + n_px_need_tr <= n_px_have) {
+                    memcpy(&(*a)[4], &top[4], 4);
+                } else {
+                    memset(&(*a)[4], (*a)[3], 4);
+                }
+            }
+        }
+    }
+    if (edges[mode].needs_left) {
+        if (have_left) {
+            int i;
+            int n_px_need = 4 << tx;
+            int n_px_have = (((s->rows - row) << !p) - y) * 4;
+            uint8_t *dst     = x == 0 ? dst_edge : dst_inner;
+            ptrdiff_t stride = x == 0 ? stride_edge : stride_inner;
+
+            if (n_px_need <= n_px_have) {
+                for (i = 0; i < n_px_need; i++)
+                    l[i] = dst[i * stride - 1];
+            } else {
+                for (i = 0; i < n_px_have; i++)
+                    l[i] = dst[i * stride - 1];
+                memset(&l[i], l[i - 1], n_px_need - n_px_have);
+            }
+        } else {
+            memset(l, 129, 4 << tx);
+        }
+    }
+
+    return mode;
+}
+
+static void intra_recon(AVCodecContext *avctx, ptrdiff_t y_off, ptrdiff_t uv_off)
+{
+    VP9Context *s = avctx->priv_data;
+    VP9Block *const b = &s->b;
+    int row = b->row, col = b->col;
+    int w4 = bwh_tab[1][b->bs][0] << 1, step1d = 1 << b->tx, n;
+    int h4 = bwh_tab[1][b->bs][1] << 1, x, y, step = 1 << (b->tx * 2);
+    int end_x = FFMIN(2 * (s->cols - col), w4);
+    int end_y = FFMIN(2 * (s->rows - row), h4);
+    int tx = 4 * s->lossless + b->tx, uvtx = b->uvtx + 4 * s->lossless;
+    int uvstep1d = 1 << b->uvtx, p;
+    uint8_t *dst = b->dst[0], *dst_r = s->cur_frame->data[0] + y_off;
+
+    for (n = 0, y = 0; y < end_y; y += step1d) {
+        uint8_t *ptr = dst, *ptr_r = dst_r;
+        for (x = 0; x < end_x;
+             x += step1d, ptr += 4 * step1d, ptr_r += 4 * step1d, n += step) {
+            int mode = b->mode[b->bs > BS_8x8 && b->tx == TX_4X4 ?
+                               y * 2 + x : 0];
+            LOCAL_ALIGNED_16(uint8_t, a_buf, [48]);
+            uint8_t *a = &a_buf[16], l[32];
+            enum TxfmType txtp = ff_vp9_intra_txfm_type[mode];
+            int eob = b->tx > TX_8X8 ? AV_RN16A(&s->eob[n]) : s->eob[n];
+
+            mode = check_intra_mode(s, mode, &a, ptr_r,
+                                    s->cur_frame->linesize[0],
+                                    ptr, b->y_stride, l,
+                                    col, x, w4, row, y, b->tx, 0);
+            s->dsp.intra_pred[b->tx][mode](ptr, b->y_stride, l, a);
+            if (eob)
+                s->dsp.itxfm_add[tx][txtp](ptr, b->y_stride,
+                                           s->block + 16 * n, eob);
+        }
+        dst_r += 4 * s->cur_frame->linesize[0] * step1d;
+        dst   += 4 * b->y_stride * step1d;
+    }
+
+    // U/V
+    h4    >>= 1;
+    w4    >>= 1;
+    end_x >>= 1;
+    end_y >>= 1;
+    step    = 1 << (b->uvtx * 2);
+    for (p = 0; p < 2; p++) {
+        dst   = b->dst[1 + p];
+        dst_r = s->cur_frame->data[1 + p] + uv_off;
+        for (n = 0, y = 0; y < end_y; y += uvstep1d) {
+            uint8_t *ptr = dst, *ptr_r = dst_r;
+            for (x = 0; x < end_x;
+                 x += uvstep1d, ptr += 4 * uvstep1d,
+                 ptr_r += 4 * uvstep1d, n += step) {
+                int mode = b->uvmode;
+                LOCAL_ALIGNED_16(uint8_t, a_buf, [48]);
+                uint8_t *a = &a_buf[16], l[32];
+                int eob    = b->uvtx > TX_8X8 ? AV_RN16A(&s->uveob[p][n])
+                                              : s->uveob[p][n];
+
+                mode = check_intra_mode(s, mode, &a, ptr_r,
+                                        s->cur_frame->linesize[1],
+                                        ptr, b->uv_stride, l,
+                                        col, x, w4, row, y, b->uvtx, p + 1);
+                s->dsp.intra_pred[b->uvtx][mode](ptr, b->uv_stride, l, a);
+                if (eob)
+                    s->dsp.itxfm_add[uvtx][DCT_DCT](ptr, b->uv_stride,
+                                                    s->uvblock[p] + 16 * n,
+                                                    eob);
+            }
+            dst_r += 4 * uvstep1d * s->cur_frame->linesize[1];
+            dst   += 4 * uvstep1d * b->uv_stride;
+        }
+    }
+}
+
+static av_always_inline void mc_luma_dir(VP9Context *s, vp9_mc_func(*mc)[2],
+                                         uint8_t *dst, ptrdiff_t dst_stride,
+                                         const uint8_t *ref,
+                                         ptrdiff_t ref_stride,
+                                         ptrdiff_t y, ptrdiff_t x,
+                                         const VP56mv *mv,
+                                         int bw, int bh, int w, int h)
+{
+    int mx = mv->x, my = mv->y;
+
+    y   += my >> 3;
+    x   += mx >> 3;
+    ref += y * ref_stride + x;
+    mx  &= 7;
+    my  &= 7;
+    // FIXME bilinear filter only needs 0/1 pixels, not 3/4
+    if (x < !!mx * 3 || y < !!my * 3 ||
+        x + !!mx * 4 > w - bw || y + !!my * 4 > h - bh) {
+        s->vdsp.emulated_edge_mc(s->edge_emu_buffer,
+                                 ref - !!my * 3 * ref_stride - !!mx * 3,
+                                 80,
+                                 ref_stride,
+                                 bw + !!mx * 7, bh + !!my * 7,
+                                 x - !!mx * 3, y - !!my * 3, w, h);
+        ref        = s->edge_emu_buffer + !!my * 3 * 80 + !!mx * 3;
+        ref_stride = 80;
+    }
+    mc[!!mx][!!my](dst, ref, dst_stride, ref_stride, bh, mx << 1, my << 1);
+}
+
+static av_always_inline void mc_chroma_dir(VP9Context *s, vp9_mc_func(*mc)[2],
+                                           uint8_t *dst_u, uint8_t *dst_v,
+                                           ptrdiff_t dst_stride,
+                                           const uint8_t *ref_u,
+                                           ptrdiff_t src_stride_u,
+                                           const uint8_t *ref_v,
+                                           ptrdiff_t src_stride_v,
+                                           ptrdiff_t y, ptrdiff_t x,
+                                           const VP56mv *mv,
+                                           int bw, int bh, int w, int h)
+{
+    int mx = mv->x, my = mv->y;
+
+    y     += my >> 4;
+    x     += mx >> 4;
+    ref_u += y * src_stride_u + x;
+    ref_v += y * src_stride_v + x;
+    mx    &= 15;
+    my    &= 15;
+    // FIXME bilinear filter only needs 0/1 pixels, not 3/4
+    if (x < !!mx * 3 || y < !!my * 3 ||
+        x + !!mx * 4 > w - bw || y + !!my * 4 > h - bh) {
+        s->vdsp.emulated_edge_mc(s->edge_emu_buffer,
+                                 ref_u - !!my * 3 * src_stride_u - !!mx * 3,
+                                 80,
+                                 src_stride_u,
+                                 bw + !!mx * 7, bh + !!my * 7,
+                                 x - !!mx * 3, y - !!my * 3, w, h);
+        ref_u = s->edge_emu_buffer + !!my * 3 * 80 + !!mx * 3;
+        mc[!!mx][!!my](dst_u, ref_u, dst_stride, 80, bh, mx, my);
+
+        s->vdsp.emulated_edge_mc(s->edge_emu_buffer,
+                                 ref_v - !!my * 3 * src_stride_v - !!mx * 3,
+                                 80,
+                                 src_stride_v,
+                                 bw + !!mx * 7, bh + !!my * 7,
+                                 x - !!mx * 3, y - !!my * 3, w, h);
+        ref_v = s->edge_emu_buffer + !!my * 3 * 80 + !!mx * 3;
+        mc[!!mx][!!my](dst_v, ref_v, dst_stride, 80, bh, mx, my);
+    } else {
+        mc[!!mx][!!my](dst_u, ref_u, dst_stride, src_stride_u, bh, mx, my);
+        mc[!!mx][!!my](dst_v, ref_v, dst_stride, src_stride_v, bh, mx, my);
+    }
+}
+
+static int inter_recon(AVCodecContext *avctx)
+{
+    static const uint8_t bwlog_tab[2][N_BS_SIZES] = {
+        { 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4 },
+        { 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 4 },
+    };
+    VP9Context *s = avctx->priv_data;
+    VP9Block *const b = &s->b;
+    int row = b->row, col = b->col;
+    AVFrame *ref1 = s->refs[s->refidx[b->ref[0]]];
+    AVFrame *ref2 = b->comp ? s->refs[s->refidx[b->ref[1]]] : NULL;
+    int w = avctx->width, h = avctx->height;
+    ptrdiff_t ls_y = b->y_stride, ls_uv = b->uv_stride;
+
+    if (!ref1->data[0] || (b->comp && !ref2->data[0]))
+        return AVERROR_INVALIDDATA;
+
+    // y inter pred
+    if (b->bs > BS_8x8) {
+        if (b->bs == BS_8x4) {
+            mc_luma_dir(s, s->dsp.mc[3][b->filter][0], b->dst[0], ls_y,
+                        ref1->data[0], ref1->linesize[0],
+                        row << 3, col << 3, &b->mv[0][0], 8, 4, w, h);
+            mc_luma_dir(s, s->dsp.mc[3][b->filter][0],
+                        b->dst[0] + 4 * ls_y, ls_y,
+                        ref1->data[0], ref1->linesize[0],
+                        (row << 3) + 4, col << 3, &b->mv[2][0], 8, 4, w, h);
+
+            if (b->comp) {
+                mc_luma_dir(s, s->dsp.mc[3][b->filter][1], b->dst[0], ls_y,
+                            ref2->data[0], ref2->linesize[0],
+                            row << 3, col << 3, &b->mv[0][1], 8, 4, w, h);
+                mc_luma_dir(s, s->dsp.mc[3][b->filter][1],
+                            b->dst[0] + 4 * ls_y, ls_y,
+                            ref2->data[0], ref2->linesize[0],
+                            (row << 3) + 4, col << 3, &b->mv[2][1], 8, 4, w, h);
+            }
+        } else if (b->bs == BS_4x8) {
+            mc_luma_dir(s, s->dsp.mc[4][b->filter][0], b->dst[0], ls_y,
+                        ref1->data[0], ref1->linesize[0],
+                        row << 3, col << 3, &b->mv[0][0], 4, 8, w, h);
+            mc_luma_dir(s, s->dsp.mc[4][b->filter][0], b->dst[0] + 4, ls_y,
+                        ref1->data[0], ref1->linesize[0],
+                        row << 3, (col << 3) + 4, &b->mv[1][0], 4, 8, w, h);
+
+            if (b->comp) {
+                mc_luma_dir(s, s->dsp.mc[4][b->filter][1], b->dst[0], ls_y,
+                            ref2->data[0], ref2->linesize[0],
+                            row << 3, col << 3, &b->mv[0][1], 4, 8, w, h);
+                mc_luma_dir(s, s->dsp.mc[4][b->filter][1], b->dst[0] + 4, ls_y,
+                            ref2->data[0], ref2->linesize[0],
+                            row << 3, (col << 3) + 4, &b->mv[1][1], 4, 8, w, h);
+            }
+        } else {
+            av_assert2(b->bs == BS_4x4);
+
+            // FIXME if two horizontally adjacent blocks have the same MV,
+            // do a w8 instead of a w4 call
+            mc_luma_dir(s, s->dsp.mc[4][b->filter][0], b->dst[0], ls_y,
+                        ref1->data[0], ref1->linesize[0],
+                        row << 3, col << 3, &b->mv[0][0], 4, 4, w, h);
+            mc_luma_dir(s, s->dsp.mc[4][b->filter][0], b->dst[0] + 4, ls_y,
+                        ref1->data[0], ref1->linesize[0],
+                        row << 3, (col << 3) + 4, &b->mv[1][0], 4, 4, w, h);
+            mc_luma_dir(s, s->dsp.mc[4][b->filter][0],
+                        b->dst[0] + 4 * ls_y, ls_y,
+                        ref1->data[0], ref1->linesize[0],
+                        (row << 3) + 4, col << 3, &b->mv[2][0], 4, 4, w, h);
+            mc_luma_dir(s, s->dsp.mc[4][b->filter][0],
+                        b->dst[0] + 4 * ls_y + 4, ls_y,
+                        ref1->data[0], ref1->linesize[0],
+                        (row << 3) + 4, (col << 3) + 4, &b->mv[3][0], 4, 4, w, h);
+
+            if (b->comp) {
+                mc_luma_dir(s, s->dsp.mc[4][b->filter][1], b->dst[0], ls_y,
+                            ref2->data[0], ref2->linesize[0],
+                            row << 3, col << 3, &b->mv[0][1], 4, 4, w, h);
+                mc_luma_dir(s, s->dsp.mc[4][b->filter][1], b->dst[0] + 4, ls_y,
+                            ref2->data[0], ref2->linesize[0],
+                            row << 3, (col << 3) + 4, &b->mv[1][1], 4, 4, w, h);
+                mc_luma_dir(s, s->dsp.mc[4][b->filter][1],
+                            b->dst[0] + 4 * ls_y, ls_y,
+                            ref2->data[0], ref2->linesize[0],
+                            (row << 3) + 4, col << 3, &b->mv[2][1], 4, 4, w, h);
+                mc_luma_dir(s, s->dsp.mc[4][b->filter][1],
+                            b->dst[0] + 4 * ls_y + 4, ls_y,
+                            ref2->data[0], ref2->linesize[0],
+                            (row << 3) + 4, (col << 3) + 4, &b->mv[3][1], 4, 4, w, h);
+            }
+        }
+    } else {
+        int bwl = bwlog_tab[0][b->bs];
+        int bw  = bwh_tab[0][b->bs][0] * 4;
+        int bh  = bwh_tab[0][b->bs][1] * 4;
+
+        mc_luma_dir(s, s->dsp.mc[bwl][b->filter][0], b->dst[0], ls_y,
+                    ref1->data[0], ref1->linesize[0],
+                    row << 3, col << 3, &b->mv[0][0], bw, bh, w, h);
+
+        if (b->comp)
+            mc_luma_dir(s, s->dsp.mc[bwl][b->filter][1], b->dst[0], ls_y,
+                        ref2->data[0], ref2->linesize[0],
+                        row << 3, col << 3, &b->mv[0][1], bw, bh, w, h);
+    }
+
+    // uv inter pred
+    {
+        int bwl = bwlog_tab[1][b->bs];
+        int bw  = bwh_tab[1][b->bs][0] * 4, bh = bwh_tab[1][b->bs][1] * 4;
+        VP56mv mvuv;
+
+        w = (w + 1) >> 1;
+        h = (h + 1) >> 1;
+        if (b->bs > BS_8x8) {
+            mvuv.x = ROUNDED_DIV(b->mv[0][0].x + b->mv[1][0].x +
+                                 b->mv[2][0].x + b->mv[3][0].x, 4);
+            mvuv.y = ROUNDED_DIV(b->mv[0][0].y + b->mv[1][0].y +
+                                 b->mv[2][0].y + b->mv[3][0].y, 4);
+        } else {
+            mvuv = b->mv[0][0];
+        }
+
+        mc_chroma_dir(s, s->dsp.mc[bwl][b->filter][0],
+                      b->dst[1], b->dst[2], ls_uv,
+                      ref1->data[1], ref1->linesize[1],
+                      ref1->data[2], ref1->linesize[2],
+                      row << 2, col << 2, &mvuv, bw, bh, w, h);
+
+        if (b->comp) {
+            if (b->bs > BS_8x8) {
+                mvuv.x = ROUNDED_DIV(b->mv[0][1].x + b->mv[1][1].x +
+                                     b->mv[2][1].x + b->mv[3][1].x, 4);
+                mvuv.y = ROUNDED_DIV(b->mv[0][1].y + b->mv[1][1].y +
+                                     b->mv[2][1].y + b->mv[3][1].y, 4);
+            } else {
+                mvuv = b->mv[0][1];
+            }
+            mc_chroma_dir(s, s->dsp.mc[bwl][b->filter][1],
+                          b->dst[1], b->dst[2], ls_uv,
+                          ref2->data[1], ref2->linesize[1],
+                          ref2->data[2], ref2->linesize[2],
+                          row << 2, col << 2, &mvuv, bw, bh, w, h);
+        }
+    }
+
+    if (!b->skip) {
+        /* mostly copied intra_reconn() */
+
+        int w4 = bwh_tab[1][b->bs][0] << 1, step1d = 1 << b->tx, n;
+        int h4 = bwh_tab[1][b->bs][1] << 1, x, y, step = 1 << (b->tx * 2);
+        int end_x = FFMIN(2 * (s->cols - col), w4);
+        int end_y = FFMIN(2 * (s->rows - row), h4);
+        int tx = 4 * s->lossless + b->tx, uvtx = b->uvtx + 4 * s->lossless;
+        int uvstep1d = 1 << b->uvtx, p;
+        uint8_t *dst = b->dst[0];
+
+        // y itxfm add
+        for (n = 0, y = 0; y < end_y; y += step1d) {
+            uint8_t *ptr = dst;
+            for (x = 0; x < end_x; x += step1d, ptr += 4 * step1d, n += step) {
+                int eob = b->tx > TX_8X8 ? AV_RN16A(&s->eob[n]) : s->eob[n];
+
+                if (eob)
+                    s->dsp.itxfm_add[tx][DCT_DCT](ptr, b->y_stride,
+                                                  s->block + 16 * n, eob);
+            }
+            dst += 4 * b->y_stride * step1d;
+        }
+
+        // uv itxfm add
+        h4    >>= 1;
+        w4    >>= 1;
+        end_x >>= 1;
+        end_y >>= 1;
+        step    = 1 << (b->uvtx * 2);
+        for (p = 0; p < 2; p++) {
+            dst = b->dst[p + 1];
+            for (n = 0, y = 0; y < end_y; y += uvstep1d) {
+                uint8_t *ptr = dst;
+                for (x = 0; x < end_x; x += uvstep1d, ptr += 4 * uvstep1d, n += step) {
+                    int eob = b->uvtx > TX_8X8 ? AV_RN16A(&s->uveob[p][n])
+                                               : s->uveob[p][n];
+                    if (eob)
+                        s->dsp.itxfm_add[uvtx][DCT_DCT](ptr, b->uv_stride,
+                                                        s->uvblock[p] + 16 * n, eob);
+                }
+                dst += 4 * uvstep1d * b->uv_stride;
+            }
+        }
+    }
+    return 0;
+}
+
+static av_always_inline void mask_edges(VP9Filter *lflvl, int is_uv,
+                                        int row_and_7, int col_and_7,
+                                        int w, int h, int col_end, int row_end,
+                                        enum TxfmMode tx, int skip_inter)
+{
+    // FIXME I'm pretty sure all loops can be replaced by a single LUT if
+    // we make VP9Filter.mask uint64_t (i.e. row/col all single variable)
+    // and make the LUT 5-indexed (bl, bp, is_uv, tx and row/col), and then
+    // use row_and_7/col_and_7 as shifts (1*col_and_7+8*row_and_7)
+
+    // the intended behaviour of the vp9 loopfilter is to work on 8-pixel
+    // edges. This means that for UV, we work on two subsampled blocks at
+    // a time, and we only use the topleft block's mode information to set
+    // things like block strength. Thus, for any block size smaller than
+    // 16x16, ignore the odd portion of the block.
+    if (tx == TX_4X4 && is_uv) {
+        if (h == 1) {
+            if (row_and_7 & 1)
+                return;
+            if (!row_end)
+                h += 1;
+        }
+        if (w == 1) {
+            if (col_and_7 & 1)
+                return;
+            if (!col_end)
+                w += 1;
+        }
+    }
+
+    if (tx == TX_4X4 && !skip_inter) {
+        int t = 1 << col_and_7, m_col = (t << w) - t, y;
+        int m_col_odd = (t << (w - 1)) - t;
+
+        // on 32-px edges, use the 8-px wide loopfilter; else, use 4-px wide
+        if (is_uv) {
+            int m_row_8 = m_col & 0x01, m_row_4 = m_col - m_row_8;
+
+            for (y = row_and_7; y < h + row_and_7; y++) {
+                int col_mask_id = 2 - !(y & 7);
+
+                lflvl->mask[is_uv][0][y][1] |= m_row_8;
+                lflvl->mask[is_uv][0][y][2] |= m_row_4;
+                // for odd lines, if the odd col is not being filtered,
+                // skip odd row also:
+                // .---. <-- a
+                // |   |
+                // |___| <-- b
+                // ^   ^
+                // c   d
+                //
+                // if a/c are even row/col and b/d are odd, and d is skipped,
+                // e.g. right edge of size-66x66.webm, then skip b also (bug)
+                if ((col_end & 1) && (y & 1)) {
+                    lflvl->mask[is_uv][1][y][col_mask_id] |= m_col_odd;
+                } else {
+                    lflvl->mask[is_uv][1][y][col_mask_id] |= m_col;
+                }
+            }
+        } else {
+            int m_row_8 = m_col & 0x11, m_row_4 = m_col - m_row_8;
+
+            for (y = row_and_7; y < h + row_and_7; y++) {
+                int col_mask_id = 2 - !(y & 3);
+
+                lflvl->mask[is_uv][0][y][1]           |= m_row_8; // row edge
+                lflvl->mask[is_uv][0][y][2]           |= m_row_4;
+                lflvl->mask[is_uv][1][y][col_mask_id] |= m_col; // col edge
+                lflvl->mask[is_uv][0][y][3]           |= m_col;
+                lflvl->mask[is_uv][1][y][3]           |= m_col;
+            }
+        }
+    } else {
+        int y, t = 1 << col_and_7, m_col = (t << w) - t;
+
+        if (!skip_inter) {
+            int mask_id = (tx == TX_8X8);
+            int l2 = tx + is_uv - 1, step1d = 1 << l2;
+            static const unsigned masks[4] = { 0xff, 0x55, 0x11, 0x01 };
+            int m_row = m_col & masks[l2];
+
+            // at odd UV col/row edges tx16/tx32 loopfilter edges, force
+            // 8wd loopfilter to prevent going off the visible edge.
+            if (is_uv && tx > TX_8X8 && (w ^ (w - 1)) == 1) {
+                int m_row_16 = ((t << (w - 1)) - t) & masks[l2];
+                int m_row_8  = m_row - m_row_16;
+
+                for (y = row_and_7; y < h + row_and_7; y++) {
+                    lflvl->mask[is_uv][0][y][0] |= m_row_16;
+                    lflvl->mask[is_uv][0][y][1] |= m_row_8;
+                }
+            } else {
+                for (y = row_and_7; y < h + row_and_7; y++)
+                    lflvl->mask[is_uv][0][y][mask_id] |= m_row;
+            }
+
+            if (is_uv && tx > TX_8X8 && (h ^ (h - 1)) == 1) {
+                for (y = row_and_7; y < h + row_and_7 - 1; y += step1d)
+                    lflvl->mask[is_uv][1][y][0] |= m_col;
+                if (y - row_and_7 == h - 1)
+                    lflvl->mask[is_uv][1][y][1] |= m_col;
+            } else {
+                for (y = row_and_7; y < h + row_and_7; y += step1d)
+                    lflvl->mask[is_uv][1][y][mask_id] |= m_col;
+            }
+        } else if (tx != TX_4X4) {
+            int mask_id;
+
+            mask_id = (tx == TX_8X8) || (is_uv && h == 1);
+            lflvl->mask[is_uv][1][row_and_7][mask_id] |= m_col;
+            mask_id = (tx == TX_8X8) || (is_uv && w == 1);
+            for (y = row_and_7; y < h + row_and_7; y++)
+                lflvl->mask[is_uv][0][y][mask_id] |= t;
+        } else if (is_uv) {
+            int t8 = t & 0x01, t4 = t - t8;
+
+            for (y = row_and_7; y < h + row_and_7; y++) {
+                lflvl->mask[is_uv][0][y][2] |= t4;
+                lflvl->mask[is_uv][0][y][1] |= t8;
+            }
+            lflvl->mask[is_uv][1][row_and_7][2 - !(row_and_7 & 7)] |= m_col;
+        } else {
+            int t8 = t & 0x11, t4 = t - t8;
+
+            for (y = row_and_7; y < h + row_and_7; y++) {
+                lflvl->mask[is_uv][0][y][2] |= t4;
+                lflvl->mask[is_uv][0][y][1] |= t8;
+            }
+            lflvl->mask[is_uv][1][row_and_7][2 - !(row_and_7 & 3)] |= m_col;
+        }
+    }
+}
+
+int ff_vp9_decode_block(AVCodecContext *avctx, int row, int col,
+                        VP9Filter *lflvl, ptrdiff_t yoff, ptrdiff_t uvoff,
+                        enum BlockLevel bl, enum BlockPartition bp)
+{
+    VP9Context *s = avctx->priv_data;
+    VP9Block *const b = &s->b;
+    enum BlockSize bs = bl * 3 + bp;
+    int ret, y, w4 = bwh_tab[1][bs][0], h4 = bwh_tab[1][bs][1], lvl;
+    int emu[2];
+
+    b->row  = row;
+    b->row7 = row & 7;
+    b->col  = col;
+    b->col7 = col & 7;
+
+    s->min_mv.x = -(128 + col * 64);
+    s->min_mv.y = -(128 + row * 64);
+    s->max_mv.x = 128 + (s->cols - col - w4) * 64;
+    s->max_mv.y = 128 + (s->rows - row - h4) * 64;
+
+    b->bs = bs;
+    decode_mode(s, b);
+    b->uvtx = b->tx - (w4 * 2 == (1 << b->tx) || h4 * 2 == (1 << b->tx));
+
+    if (!b->skip) {
+        if ((ret = decode_coeffs(avctx)) < 0)
+            return ret;
+    } else {
+        int pl;
+
+        memset(&s->above_y_nnz_ctx[col * 2], 0, w4 * 2);
+        memset(&s->left_y_nnz_ctx[(row & 7) << 1], 0, h4 * 2);
+        for (pl = 0; pl < 2; pl++) {
+            memset(&s->above_uv_nnz_ctx[pl][col], 0, w4);
+            memset(&s->left_uv_nnz_ctx[pl][row & 7], 0, h4);
+        }
+    }
+
+    /* Emulated overhangs if the stride of the target buffer can't hold.
+     * This allows to support emu-edge and so on even if we have large
+     * block overhangs. */
+    emu[0] = (col + w4) * 8 > s->cur_frame->linesize[0] ||
+             (row + h4) > s->rows + 2 * !(avctx->flags & CODEC_FLAG_EMU_EDGE);
+    emu[1] = (col + w4) * 4 > s->cur_frame->linesize[1] ||
+             (row + h4) > s->rows + 2 * !(avctx->flags & CODEC_FLAG_EMU_EDGE);
+    if (emu[0]) {
+        b->dst[0]   = s->tmp_y;
+        b->y_stride = 64;
+    } else {
+        b->dst[0]   = s->cur_frame->data[0] + yoff;
+        b->y_stride = s->cur_frame->linesize[0];
+    }
+    if (emu[1]) {
+        b->dst[1]    = s->tmp_uv[0];
+        b->dst[2]    = s->tmp_uv[1];
+        b->uv_stride = 32;
+    } else {
+        b->dst[1]    = s->cur_frame->data[1] + uvoff;
+        b->dst[2]    = s->cur_frame->data[2] + uvoff;
+        b->uv_stride = s->cur_frame->linesize[1];
+    }
+    if (b->intra) {
+        intra_recon(avctx, yoff, uvoff);
+    } else {
+        if ((ret = inter_recon(avctx)) < 0)
+            return ret;
+    }
+    if (emu[0]) {
+        int w = FFMIN(s->cols - col, w4) * 8;
+        int h = FFMIN(s->rows - row, h4) * 8;
+        int n, o = 0;
+
+        for (n = 0; o < w; n++) {
+            int bw = 64 >> n;
+
+            av_assert2(n <= 4);
+            if (w & bw) {
+                s->dsp.mc[n][0][0][0][0](s->cur_frame->data[0] + yoff + o,
+                                         s->tmp_y + o,
+                                         s->cur_frame->linesize[0],
+                                         64, h, 0, 0);
+                o += bw;
+            }
+        }
+    }
+    if (emu[1]) {
+        int w = FFMIN(s->cols - col, w4) * 4;
+        int h = FFMIN(s->rows - row, h4) * 4;
+        int n, o = 0;
+
+        for (n = 1; o < w; n++) {
+            int bw = 64 >> n;
+
+            av_assert2(n <= 4);
+            if (w & bw) {
+                s->dsp.mc[n][0][0][0][0](s->cur_frame->data[1] + uvoff + o,
+                                         s->tmp_uv[0] + o,
+                                         s->cur_frame->linesize[1],
+                                         32, h, 0, 0);
+                s->dsp.mc[n][0][0][0][0](s->cur_frame->data[2] + uvoff + o,
+                                         s->tmp_uv[1] + o,
+                                         s->cur_frame->linesize[2],
+                                         32, h, 0, 0);
+                o += bw;
+            }
+        }
+    }
+
+    // pick filter level and find edges to apply filter to
+    if (s->filter.level &&
+        (lvl = s->segmentation.feat[b->seg_id].lflvl[b->intra ? 0 : b->ref[0] + 1]
+                                                    [b->mode[3] != ZEROMV]) > 0) {
+        int x_end = FFMIN(s->cols - col, w4);
+        int y_end = FFMIN(s->rows - row, h4);
+        int skip_inter = !b->intra && b->skip;
+
+        for (y = 0; y < h4; y++)
+            memset(&lflvl->level[((row & 7) + y) * 8 + (col & 7)], lvl, w4);
+        mask_edges(lflvl, 0, row & 7, col & 7, x_end, y_end, 0, 0, b->tx, skip_inter);
+        mask_edges(lflvl, 1, row & 7, col & 7, x_end, y_end,
+                   s->cols & 1 && col + w4 >= s->cols ? s->cols & 7 : 0,
+                   s->rows & 1 && row + h4 >= s->rows ? s->rows & 7 : 0,
+                   b->uvtx, skip_inter);
+
+        if (!s->filter.lim_lut[lvl]) {
+            int sharp = s->filter.sharpness;
+            int limit = lvl;
+
+            if (sharp > 0) {
+                limit >>= (sharp + 3) >> 2;
+                limit   = FFMIN(limit, 9 - sharp);
+            }
+            limit = FFMAX(limit, 1);
+
+            s->filter.lim_lut[lvl]   = limit;
+            s->filter.mblim_lut[lvl] = 2 * (lvl + 2) + limit;
+        }
+    }
+
+    return 0;
+}