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, 1270 insertions, 0 deletions

diff --git a/libavcodec/vp9.c b/libavcodec/vp9.c
new file mode 100644
index 0000000000..9048700fb7
--- /dev/null
+++ b/libavcodec/vp9.c
@@ -0,0 +1,1270 @@
+/*
+ * 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"
+
+#define VP9_SYNCCODE 0x498342
+#define MAX_PROB 255
+
+static void vp9_decode_flush(AVCodecContext *avctx)
+{
+    VP9Context *s = avctx->priv_data;
+    int i;
+
+    for (i = 0; i < FF_ARRAY_ELEMS(s->refs); i++)
+        av_frame_unref(s->refs[i]);
+}
+
+static int update_size(AVCodecContext *avctx, int w, int h)
+{
+    VP9Context *s = avctx->priv_data;
+    uint8_t *p;
+
+    if (s->above_partition_ctx && w == avctx->width && h == avctx->height)
+        return 0;
+
+    vp9_decode_flush(avctx);
+
+    if (w <= 0 || h <= 0)
+        return AVERROR_INVALIDDATA;
+
+    avctx->width  = w;
+    avctx->height = h;
+    s->sb_cols    = (w + 63) >> 6;
+    s->sb_rows    = (h + 63) >> 6;
+    s->cols       = (w +  7) >> 3;
+    s->rows       = (h +  7) >> 3;
+
+#define assign(var, type, n) var = (type)p; p += s->sb_cols * n * sizeof(*var)
+    av_free(s->above_partition_ctx);
+    p = av_malloc(s->sb_cols *
+                  (240 + sizeof(*s->lflvl) + 16 * sizeof(*s->above_mv_ctx) +
+                   64 * s->sb_rows * (1 + sizeof(*s->mv[0]) * 2)));
+    if (!p)
+        return AVERROR(ENOMEM);
+    assign(s->above_partition_ctx, uint8_t *,     8);
+    assign(s->above_skip_ctx,      uint8_t *,     8);
+    assign(s->above_txfm_ctx,      uint8_t *,     8);
+    assign(s->above_mode_ctx,      uint8_t *,    16);
+    assign(s->above_y_nnz_ctx,     uint8_t *,    16);
+    assign(s->above_uv_nnz_ctx[0], uint8_t *,     8);
+    assign(s->above_uv_nnz_ctx[1], uint8_t *,     8);
+    assign(s->intra_pred_data[0],  uint8_t *,    64);
+    assign(s->intra_pred_data[1],  uint8_t *,    32);
+    assign(s->intra_pred_data[2],  uint8_t *,    32);
+    assign(s->above_segpred_ctx,   uint8_t *,     8);
+    assign(s->above_intra_ctx,     uint8_t *,     8);
+    assign(s->above_comp_ctx,      uint8_t *,     8);
+    assign(s->above_ref_ctx,       uint8_t *,     8);
+    assign(s->above_filter_ctx,    uint8_t *,     8);
+    assign(s->lflvl,               VP9Filter *,   1);
+    assign(s->above_mv_ctx,        VP56mv(*)[2], 16);
+    assign(s->segmentation_map,    uint8_t *,      64 * s->sb_rows);
+    assign(s->mv[0],               VP9MVRefPair *, 64 * s->sb_rows);
+    assign(s->mv[1],               VP9MVRefPair *, 64 * s->sb_rows);
+#undef assign
+
+    return 0;
+}
+
+// The sign bit is at the end, not the start, of a bit sequence
+static av_always_inline int get_bits_with_sign(GetBitContext *gb, int n)
+{
+    int v = get_bits(gb, n);
+    return get_bits1(gb) ? -v : v;
+}
+
+static av_always_inline int inv_recenter_nonneg(int v, int m)
+{
+    if (v > 2 * m)
+        return v;
+    if (v & 1)
+        return m - ((v + 1) >> 1);
+    return m + (v >> 1);
+}
+
+// differential forward probability updates
+static int update_prob(VP56RangeCoder *c, int p)
+{
+    static const int inv_map_table[MAX_PROB - 1] = {
+          7,  20,  33,  46,  59,  72,  85,  98, 111, 124, 137, 150, 163, 176,
+        189, 202, 215, 228, 241, 254,   1,   2,   3,   4,   5,   6,   8,   9,
+         10,  11,  12,  13,  14,  15,  16,  17,  18,  19,  21,  22,  23,  24,
+         25,  26,  27,  28,  29,  30,  31,  32,  34,  35,  36,  37,  38,  39,
+         40,  41,  42,  43,  44,  45,  47,  48,  49,  50,  51,  52,  53,  54,
+         55,  56,  57,  58,  60,  61,  62,  63,  64,  65,  66,  67,  68,  69,
+         70,  71,  73,  74,  75,  76,  77,  78,  79,  80,  81,  82,  83,  84,
+         86,  87,  88,  89,  90,  91,  92,  93,  94,  95,  96,  97,  99, 100,
+        101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 112, 113, 114, 115,
+        116, 117, 118, 119, 120, 121, 122, 123, 125, 126, 127, 128, 129, 130,
+        131, 132, 133, 134, 135, 136, 138, 139, 140, 141, 142, 143, 144, 145,
+        146, 147, 148, 149, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160,
+        161, 162, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175,
+        177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 190, 191,
+        192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 203, 204, 205, 206,
+        207, 208, 209, 210, 211, 212, 213, 214, 216, 217, 218, 219, 220, 221,
+        222, 223, 224, 225, 226, 227, 229, 230, 231, 232, 233, 234, 235, 236,
+        237, 238, 239, 240, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251,
+        252, 253,
+    };
+    int d;
+
+    /* This code is trying to do a differential probability update. For a
+     * current probability A in the range [1, 255], the difference to a new
+     * probability of any value can be expressed differentially as 1-A, 255-A
+     * where some part of this (absolute range) exists both in positive as
+     * well as the negative part, whereas another part only exists in one
+     * half. We're trying to code this shared part differentially, i.e.
+     * times two where the value of the lowest bit specifies the sign, and
+     * the single part is then coded on top of this. This absolute difference
+     * then again has a value of [0, 254], but a bigger value in this range
+     * indicates that we're further away from the original value A, so we
+     * can code this as a VLC code, since higher values are increasingly
+     * unlikely. The first 20 values in inv_map_table[] allow 'cheap, rough'
+     * updates vs. the 'fine, exact' updates further down the range, which
+     * adds one extra dimension to this differential update model. */
+
+    if (!vp8_rac_get(c)) {
+        d = vp8_rac_get_uint(c, 4) + 0;
+    } else if (!vp8_rac_get(c)) {
+        d = vp8_rac_get_uint(c, 4) + 16;
+    } else if (!vp8_rac_get(c)) {
+        d = vp8_rac_get_uint(c, 5) + 32;
+    } else {
+        d = vp8_rac_get_uint(c, 7);
+        if (d >= 65) {
+            d = (d << 1) - 65 + vp8_rac_get(c);
+            d = av_clip(d, 0, MAX_PROB - 65 - 1);
+        }
+        d += 64;
+    }
+
+    return p <= 128
+           ?   1 + inv_recenter_nonneg(inv_map_table[d], p - 1)
+           : 255 - inv_recenter_nonneg(inv_map_table[d], 255 - p);
+}
+
+static int decode_frame_header(AVCodecContext *avctx,
+                               const uint8_t *data, int size, int *ref)
+{
+    VP9Context *s = avctx->priv_data;
+    int c, i, j, k, l, m, n, w, h, max, size2, ret, sharp;
+    int last_invisible;
+    const uint8_t *data2;
+
+    /* general header */
+    if ((ret = init_get_bits8(&s->gb, data, size)) < 0) {
+        av_log(avctx, AV_LOG_ERROR, "Failed to initialize bitstream reader\n");
+        return ret;
+    }
+    if (get_bits(&s->gb, 2) != 0x2) { // frame marker
+        av_log(avctx, AV_LOG_ERROR, "Invalid frame marker\n");
+        return AVERROR_INVALIDDATA;
+    }
+    s->profile = get_bits1(&s->gb);
+    if (get_bits1(&s->gb)) { // reserved bit
+        av_log(avctx, AV_LOG_ERROR, "Reserved bit should be zero\n");
+        return AVERROR_INVALIDDATA;
+    }
+    if (get_bits1(&s->gb)) {
+        *ref = get_bits(&s->gb, 3);
+        return 0;
+    }
+
+    s->last_keyframe = s->keyframe;
+    s->keyframe      = !get_bits1(&s->gb);
+
+    last_invisible = s->invisible;
+    s->invisible   = !get_bits1(&s->gb);
+    s->errorres    = get_bits1(&s->gb);
+    // FIXME disable this upon resolution change
+    s->use_last_frame_mvs = !s->errorres && !last_invisible;
+
+    if (s->keyframe) {
+        if (get_bits_long(&s->gb, 24) != VP9_SYNCCODE) { // synccode
+            av_log(avctx, AV_LOG_ERROR, "Invalid sync code\n");
+            return AVERROR_INVALIDDATA;
+        }
+        s->colorspace = get_bits(&s->gb, 3);
+        if (s->colorspace == 7) { // RGB = profile 1
+            av_log(avctx, AV_LOG_ERROR, "RGB not supported in profile 0\n");
+            return AVERROR_INVALIDDATA;
+        }
+        s->fullrange = get_bits1(&s->gb);
+        // for profile 1, here follows the subsampling bits
+        s->refreshrefmask = 0xff;
+        w = get_bits(&s->gb, 16) + 1;
+        h = get_bits(&s->gb, 16) + 1;
+        if (get_bits1(&s->gb)) // display size
+            skip_bits(&s->gb, 32);
+    } else {
+        s->intraonly = s->invisible ? get_bits1(&s->gb) : 0;
+        s->resetctx  = s->errorres ? 0 : get_bits(&s->gb, 2);
+        if (s->intraonly) {
+            if (get_bits_long(&s->gb, 24) != VP9_SYNCCODE) { // synccode
+                av_log(avctx, AV_LOG_ERROR, "Invalid sync code\n");
+                return AVERROR_INVALIDDATA;
+            }
+            s->refreshrefmask = get_bits(&s->gb, 8);
+            w = get_bits(&s->gb, 16) + 1;
+            h = get_bits(&s->gb, 16) + 1;
+            if (get_bits1(&s->gb)) // display size
+                skip_bits(&s->gb, 32);
+        } else {
+            s->refreshrefmask = get_bits(&s->gb, 8);
+            s->refidx[0]      = get_bits(&s->gb, 3);
+            s->signbias[0]    = get_bits1(&s->gb);
+            s->refidx[1]      = get_bits(&s->gb, 3);
+            s->signbias[1]    = get_bits1(&s->gb);
+            s->refidx[2]      = get_bits(&s->gb, 3);
+            s->signbias[2]    = get_bits1(&s->gb);
+            if (!s->refs[s->refidx[0]]->buf[0] ||
+                !s->refs[s->refidx[1]]->buf[0] ||
+                !s->refs[s->refidx[2]]->buf[0]) {
+                av_log(avctx, AV_LOG_ERROR,
+                       "Not all references are available\n");
+                return AVERROR_INVALIDDATA;
+            }
+            if (get_bits1(&s->gb)) {
+                w = s->refs[s->refidx[0]]->width;
+                h = s->refs[s->refidx[0]]->height;
+            } else if (get_bits1(&s->gb)) {
+                w = s->refs[s->refidx[1]]->width;
+                h = s->refs[s->refidx[1]]->height;
+            } else if (get_bits1(&s->gb)) {
+                w = s->refs[s->refidx[2]]->width;
+                h = s->refs[s->refidx[2]]->height;
+            } else {
+                w = get_bits(&s->gb, 16) + 1;
+                h = get_bits(&s->gb, 16) + 1;
+            }
+            if (get_bits1(&s->gb)) // display size
+                skip_bits(&s->gb, 32);
+            s->highprecisionmvs = get_bits1(&s->gb);
+            s->filtermode       = get_bits1(&s->gb) ? FILTER_SWITCHABLE :
+                                  get_bits(&s->gb, 2);
+            s->allowcompinter   = s->signbias[0] != s->signbias[1] ||
+                                  s->signbias[0] != s->signbias[2];
+            if (s->allowcompinter) {
+                if (s->signbias[0] == s->signbias[1]) {
+                    s->fixcompref    = 2;
+                    s->varcompref[0] = 0;
+                    s->varcompref[1] = 1;
+                } else if (s->signbias[0] == s->signbias[2]) {
+                    s->fixcompref    = 1;
+                    s->varcompref[0] = 0;
+                    s->varcompref[1] = 2;
+                } else {
+                    s->fixcompref    = 0;
+                    s->varcompref[0] = 1;
+                    s->varcompref[1] = 2;
+                }
+            }
+        }
+    }
+
+    s->refreshctx   = s->errorres ? 0 : get_bits1(&s->gb);
+    s->parallelmode = s->errorres ? 1 : get_bits1(&s->gb);
+    s->framectxid   = c = get_bits(&s->gb, 2);
+
+    /* loopfilter header data */
+    s->filter.level = get_bits(&s->gb, 6);
+    sharp           = get_bits(&s->gb, 3);
+    /* If sharpness changed, reinit lim/mblim LUTs. if it didn't change,
+     * keep the old cache values since they are still valid. */
+    if (s->filter.sharpness != sharp)
+        memset(s->filter.lim_lut, 0, sizeof(s->filter.lim_lut));
+    s->filter.sharpness = sharp;
+    if ((s->lf_delta.enabled = get_bits1(&s->gb))) {
+        if (get_bits1(&s->gb)) {
+            for (i = 0; i < 4; i++)
+                if (get_bits1(&s->gb))
+                    s->lf_delta.ref[i] = get_bits_with_sign(&s->gb, 6);
+            for (i = 0; i < 2; i++)
+                if (get_bits1(&s->gb))
+                    s->lf_delta.mode[i] = get_bits_with_sign(&s->gb, 6);
+        }
+    } else {
+        memset(&s->lf_delta, 0, sizeof(s->lf_delta));
+    }
+
+    /* quantization header data */
+    s->yac_qi      = get_bits(&s->gb, 8);
+    s->ydc_qdelta  = get_bits1(&s->gb) ? get_bits_with_sign(&s->gb, 4) : 0;
+    s->uvdc_qdelta = get_bits1(&s->gb) ? get_bits_with_sign(&s->gb, 4) : 0;
+    s->uvac_qdelta = get_bits1(&s->gb) ? get_bits_with_sign(&s->gb, 4) : 0;
+    s->lossless    = s->yac_qi == 0 && s->ydc_qdelta == 0 &&
+                     s->uvdc_qdelta == 0 && s->uvac_qdelta == 0;
+
+    /* segmentation header info */
+    if ((s->segmentation.enabled = get_bits1(&s->gb))) {
+        if ((s->segmentation.update_map = get_bits1(&s->gb))) {
+            for (i = 0; i < 7; i++)
+                s->prob.seg[i] = get_bits1(&s->gb) ?
+                                 get_bits(&s->gb, 8) : 255;
+            if ((s->segmentation.temporal = get_bits1(&s->gb)))
+                for (i = 0; i < 3; i++)
+                    s->prob.segpred[i] = get_bits1(&s->gb) ?
+                                         get_bits(&s->gb, 8) : 255;
+        }
+
+        if (get_bits1(&s->gb)) {
+            s->segmentation.absolute_vals = get_bits1(&s->gb);
+            for (i = 0; i < 8; i++) {
+                if ((s->segmentation.feat[i].q_enabled = get_bits1(&s->gb)))
+                    s->segmentation.feat[i].q_val = get_bits_with_sign(&s->gb, 8);
+                if ((s->segmentation.feat[i].lf_enabled = get_bits1(&s->gb)))
+                    s->segmentation.feat[i].lf_val = get_bits_with_sign(&s->gb, 6);
+                if ((s->segmentation.feat[i].ref_enabled = get_bits1(&s->gb)))
+                    s->segmentation.feat[i].ref_val = get_bits(&s->gb, 2);
+                s->segmentation.feat[i].skip_enabled = get_bits1(&s->gb);
+            }
+        }
+    } else {
+        s->segmentation.feat[0].q_enabled    = 0;
+        s->segmentation.feat[0].lf_enabled   = 0;
+        s->segmentation.feat[0].skip_enabled = 0;
+        s->segmentation.feat[0].ref_enabled  = 0;
+    }
+
+    // set qmul[] based on Y/UV, AC/DC and segmentation Q idx deltas
+    for (i = 0; i < (s->segmentation.enabled ? 8 : 1); i++) {
+        int qyac, qydc, quvac, quvdc, lflvl, sh;
+
+        if (s->segmentation.feat[i].q_enabled) {
+            if (s->segmentation.absolute_vals)
+                qyac = s->segmentation.feat[i].q_val;
+            else
+                qyac = s->yac_qi + s->segmentation.feat[i].q_val;
+        } else {
+            qyac = s->yac_qi;
+        }
+        qydc  = av_clip_uintp2(qyac + s->ydc_qdelta, 8);
+        quvdc = av_clip_uintp2(qyac + s->uvdc_qdelta, 8);
+        quvac = av_clip_uintp2(qyac + s->uvac_qdelta, 8);
+        qyac  = av_clip_uintp2(qyac, 8);
+
+        s->segmentation.feat[i].qmul[0][0] = ff_vp9_dc_qlookup[qydc];
+        s->segmentation.feat[i].qmul[0][1] = ff_vp9_ac_qlookup[qyac];
+        s->segmentation.feat[i].qmul[1][0] = ff_vp9_dc_qlookup[quvdc];
+        s->segmentation.feat[i].qmul[1][1] = ff_vp9_ac_qlookup[quvac];
+
+        sh = s->filter.level >= 32;
+        if (s->segmentation.feat[i].lf_enabled) {
+            if (s->segmentation.absolute_vals)
+                lflvl = s->segmentation.feat[i].lf_val;
+            else
+                lflvl = s->filter.level + s->segmentation.feat[i].lf_val;
+        } else {
+            lflvl = s->filter.level;
+        }
+        s->segmentation.feat[i].lflvl[0][0] =
+        s->segmentation.feat[i].lflvl[0][1] =
+            av_clip_uintp2(lflvl + (s->lf_delta.ref[0] << sh), 6);
+        for (j = 1; j < 4; j++) {
+            s->segmentation.feat[i].lflvl[j][0] =
+                av_clip_uintp2(lflvl + ((s->lf_delta.ref[j] +
+                                         s->lf_delta.mode[0]) << sh), 6);
+            s->segmentation.feat[i].lflvl[j][1] =
+                av_clip_uintp2(lflvl + ((s->lf_delta.ref[j] +
+                                         s->lf_delta.mode[1]) << sh), 6);
+        }
+    }
+
+    /* tiling info */
+    if ((ret = update_size(avctx, w, h)) < 0) {
+        av_log(avctx, AV_LOG_ERROR,
+               "Failed to initialize decoder for %dx%d\n", w, h);
+        return ret;
+    }
+    for (s->tiling.log2_tile_cols = 0;
+         (s->sb_cols >> s->tiling.log2_tile_cols) > 64;
+         s->tiling.log2_tile_cols++) ;
+    for (max = 0; (s->sb_cols >> max) >= 4; max++) ;
+    max = FFMAX(0, max - 1);
+    while (max > s->tiling.log2_tile_cols) {
+        if (get_bits1(&s->gb))
+            s->tiling.log2_tile_cols++;
+        else
+            break;
+    }
+    s->tiling.log2_tile_rows = decode012(&s->gb);
+    s->tiling.tile_rows      = 1 << s->tiling.log2_tile_rows;
+    if (s->tiling.tile_cols != (1 << s->tiling.log2_tile_cols)) {
+        s->tiling.tile_cols = 1 << s->tiling.log2_tile_cols;
+        s->c_b              = av_fast_realloc(s->c_b, &s->c_b_size,
+                                              sizeof(VP56RangeCoder) *
+                                              s->tiling.tile_cols);
+        if (!s->c_b) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Ran out of memory during range coder init\n");
+            return AVERROR(ENOMEM);
+        }
+    }
+
+    if (s->keyframe || s->errorres || s->intraonly) {
+        s->prob_ctx[0].p =
+        s->prob_ctx[1].p =
+        s->prob_ctx[2].p =
+        s->prob_ctx[3].p = ff_vp9_default_probs;
+        memcpy(s->prob_ctx[0].coef, ff_vp9_default_coef_probs,
+               sizeof(ff_vp9_default_coef_probs));
+        memcpy(s->prob_ctx[1].coef, ff_vp9_default_coef_probs,
+               sizeof(ff_vp9_default_coef_probs));
+        memcpy(s->prob_ctx[2].coef, ff_vp9_default_coef_probs,
+               sizeof(ff_vp9_default_coef_probs));
+        memcpy(s->prob_ctx[3].coef, ff_vp9_default_coef_probs,
+               sizeof(ff_vp9_default_coef_probs));
+    }
+
+    // next 16 bits is size of the rest of the header (arith-coded)
+    size2 = get_bits(&s->gb, 16);
+    data2 = align_get_bits(&s->gb);
+    if (size2 > size - (data2 - data)) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid compressed header size\n");
+        return AVERROR_INVALIDDATA;
+    }
+    ff_vp56_init_range_decoder(&s->c, data2, size2);
+    if (vp56_rac_get_prob_branchy(&s->c, 128)) { // marker bit
+        av_log(avctx, AV_LOG_ERROR, "Marker bit was set\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    if (s->keyframe || s->intraonly)
+        memset(s->counts.coef, 0,
+               sizeof(s->counts.coef) + sizeof(s->counts.eob));
+    else
+        memset(&s->counts, 0, sizeof(s->counts));
+
+    /* FIXME is it faster to not copy here, but do it down in the fw updates
+     * as explicit copies if the fw update is missing (and skip the copy upon
+     * fw update)? */
+    s->prob.p = s->prob_ctx[c].p;
+
+    // txfm updates
+    if (s->lossless) {
+        s->txfmmode = TX_4X4;
+    } else {
+        s->txfmmode = vp8_rac_get_uint(&s->c, 2);
+        if (s->txfmmode == 3)
+            s->txfmmode += vp8_rac_get(&s->c);
+
+        if (s->txfmmode == TX_SWITCHABLE) {
+            for (i = 0; i < 2; i++)
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.tx8p[i] = update_prob(&s->c, s->prob.p.tx8p[i]);
+            for (i = 0; i < 2; i++)
+                for (j = 0; j < 2; j++)
+                    if (vp56_rac_get_prob_branchy(&s->c, 252))
+                        s->prob.p.tx16p[i][j] =
+                            update_prob(&s->c, s->prob.p.tx16p[i][j]);
+            for (i = 0; i < 2; i++)
+                for (j = 0; j < 3; j++)
+                    if (vp56_rac_get_prob_branchy(&s->c, 252))
+                        s->prob.p.tx32p[i][j] =
+                            update_prob(&s->c, s->prob.p.tx32p[i][j]);
+        }
+    }
+
+    // coef updates
+    for (i = 0; i < 4; i++) {
+        uint8_t (*ref)[2][6][6][3] = s->prob_ctx[c].coef[i];
+        if (vp8_rac_get(&s->c)) {
+            for (j = 0; j < 2; j++)
+                for (k = 0; k < 2; k++)
+                    for (l = 0; l < 6; l++)
+                        for (m = 0; m < 6; m++) {
+                            uint8_t *p = s->prob.coef[i][j][k][l][m];
+                            uint8_t *r = ref[j][k][l][m];
+                            if (m >= 3 && l == 0) // dc only has 3 pt
+                                break;
+                            for (n = 0; n < 3; n++) {
+                                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                                    p[n] = update_prob(&s->c, r[n]);
+                                else
+                                    p[n] = r[n];
+                            }
+                            p[3] = 0;
+                        }
+        } else {
+            for (j = 0; j < 2; j++)
+                for (k = 0; k < 2; k++)
+                    for (l = 0; l < 6; l++)
+                        for (m = 0; m < 6; m++) {
+                            uint8_t *p = s->prob.coef[i][j][k][l][m];
+                            uint8_t *r = ref[j][k][l][m];
+                            if (m > 3 && l == 0) // dc only has 3 pt
+                                break;
+                            memcpy(p, r, 3);
+                            p[3] = 0;
+                        }
+        }
+        if (s->txfmmode == i)
+            break;
+    }
+
+    // mode updates
+    for (i = 0; i < 3; i++)
+        if (vp56_rac_get_prob_branchy(&s->c, 252))
+            s->prob.p.skip[i] = update_prob(&s->c, s->prob.p.skip[i]);
+    if (!s->keyframe && !s->intraonly) {
+        for (i = 0; i < 7; i++)
+            for (j = 0; j < 3; j++)
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.mv_mode[i][j] =
+                        update_prob(&s->c, s->prob.p.mv_mode[i][j]);
+
+        if (s->filtermode == FILTER_SWITCHABLE)
+            for (i = 0; i < 4; i++)
+                for (j = 0; j < 2; j++)
+                    if (vp56_rac_get_prob_branchy(&s->c, 252))
+                        s->prob.p.filter[i][j] =
+                            update_prob(&s->c, s->prob.p.filter[i][j]);
+
+        for (i = 0; i < 4; i++)
+            if (vp56_rac_get_prob_branchy(&s->c, 252))
+                s->prob.p.intra[i] = update_prob(&s->c, s->prob.p.intra[i]);
+
+        if (s->allowcompinter) {
+            s->comppredmode = vp8_rac_get(&s->c);
+            if (s->comppredmode)
+                s->comppredmode += vp8_rac_get(&s->c);
+            if (s->comppredmode == PRED_SWITCHABLE)
+                for (i = 0; i < 5; i++)
+                    if (vp56_rac_get_prob_branchy(&s->c, 252))
+                        s->prob.p.comp[i] =
+                            update_prob(&s->c, s->prob.p.comp[i]);
+        } else {
+            s->comppredmode = PRED_SINGLEREF;
+        }
+
+        if (s->comppredmode != PRED_COMPREF) {
+            for (i = 0; i < 5; i++) {
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.single_ref[i][0] =
+                        update_prob(&s->c, s->prob.p.single_ref[i][0]);
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.single_ref[i][1] =
+                        update_prob(&s->c, s->prob.p.single_ref[i][1]);
+            }
+        }
+
+        if (s->comppredmode != PRED_SINGLEREF) {
+            for (i = 0; i < 5; i++)
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.comp_ref[i] =
+                        update_prob(&s->c, s->prob.p.comp_ref[i]);
+        }
+
+        for (i = 0; i < 4; i++)
+            for (j = 0; j < 9; j++)
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.y_mode[i][j] =
+                        update_prob(&s->c, s->prob.p.y_mode[i][j]);
+
+        for (i = 0; i < 4; i++)
+            for (j = 0; j < 4; j++)
+                for (k = 0; k < 3; k++)
+                    if (vp56_rac_get_prob_branchy(&s->c, 252))
+                        s->prob.p.partition[3 - i][j][k] =
+                            update_prob(&s->c,
+                                        s->prob.p.partition[3 - i][j][k]);
+
+        // mv fields don't use the update_prob subexp model for some reason
+        for (i = 0; i < 3; i++)
+            if (vp56_rac_get_prob_branchy(&s->c, 252))
+                s->prob.p.mv_joint[i] = (vp8_rac_get_uint(&s->c, 7) << 1) | 1;
+
+        for (i = 0; i < 2; i++) {
+            if (vp56_rac_get_prob_branchy(&s->c, 252))
+                s->prob.p.mv_comp[i].sign =
+                    (vp8_rac_get_uint(&s->c, 7) << 1) | 1;
+
+            for (j = 0; j < 10; j++)
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.mv_comp[i].classes[j] =
+                        (vp8_rac_get_uint(&s->c, 7) << 1) | 1;
+
+            if (vp56_rac_get_prob_branchy(&s->c, 252))
+                s->prob.p.mv_comp[i].class0 =
+                    (vp8_rac_get_uint(&s->c, 7) << 1) | 1;
+
+            for (j = 0; j < 10; j++)
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.mv_comp[i].bits[j] =
+                        (vp8_rac_get_uint(&s->c, 7) << 1) | 1;
+        }
+
+        for (i = 0; i < 2; i++) {
+            for (j = 0; j < 2; j++)
+                for (k = 0; k < 3; k++)
+                    if (vp56_rac_get_prob_branchy(&s->c, 252))
+                        s->prob.p.mv_comp[i].class0_fp[j][k] =
+                            (vp8_rac_get_uint(&s->c, 7) << 1) | 1;
+
+            for (j = 0; j < 3; j++)
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.mv_comp[i].fp[j] =
+                        (vp8_rac_get_uint(&s->c, 7) << 1) | 1;
+        }
+
+        if (s->highprecisionmvs) {
+            for (i = 0; i < 2; i++) {
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.mv_comp[i].class0_hp =
+                        (vp8_rac_get_uint(&s->c, 7) << 1) | 1;
+
+                if (vp56_rac_get_prob_branchy(&s->c, 252))
+                    s->prob.p.mv_comp[i].hp =
+                        (vp8_rac_get_uint(&s->c, 7) << 1) | 1;
+            }
+        }
+    }
+
+    return (data2 - data) + size2;
+}
+
+static int decode_subblock(AVCodecContext *avctx, int row, int col,
+                           VP9Filter *lflvl,
+                           ptrdiff_t yoff, ptrdiff_t uvoff, enum BlockLevel bl)
+{
+    VP9Context *s = avctx->priv_data;
+    int c = ((s->above_partition_ctx[col]       >> (3 - bl)) & 1) |
+            (((s->left_partition_ctx[row & 0x7] >> (3 - bl)) & 1) << 1);
+    int ret;
+    const uint8_t *p = s->keyframe ? ff_vp9_default_kf_partition_probs[bl][c]
+                                   : s->prob.p.partition[bl][c];
+    enum BlockPartition bp;
+    ptrdiff_t hbs = 4 >> bl;
+
+    if (bl == BL_8X8) {
+        bp  = vp8_rac_get_tree(&s->c, ff_vp9_partition_tree, p);
+        ret = ff_vp9_decode_block(avctx, row, col, lflvl, yoff, uvoff, bl, bp);
+    } else if (col + hbs < s->cols) {
+        if (row + hbs < s->rows) {
+            bp = vp8_rac_get_tree(&s->c, ff_vp9_partition_tree, p);
+            switch (bp) {
+            case PARTITION_NONE:
+                ret = ff_vp9_decode_block(avctx, row, col, lflvl, yoff, uvoff,
+                                          bl, bp);
+                break;
+            case PARTITION_H:
+                ret = ff_vp9_decode_block(avctx, row, col, lflvl, yoff, uvoff,
+                                          bl, bp);
+                if (!ret) {
+                    yoff  += hbs * 8 * s->cur_frame->linesize[0];
+                    uvoff += hbs * 4 * s->cur_frame->linesize[1];
+                    ret    = ff_vp9_decode_block(avctx, row + hbs, col, lflvl,
+                                                 yoff, uvoff, bl, bp);
+                }
+                break;
+            case PARTITION_V:
+                ret = ff_vp9_decode_block(avctx, row, col, lflvl, yoff, uvoff,
+                                          bl, bp);
+                if (!ret) {
+                    yoff  += hbs * 8;
+                    uvoff += hbs * 4;
+                    ret    = ff_vp9_decode_block(avctx, row, col + hbs, lflvl,
+                                                 yoff, uvoff, bl, bp);
+                }
+                break;
+            case PARTITION_SPLIT:
+                ret = decode_subblock(avctx, row, col, lflvl,
+                                      yoff, uvoff, bl + 1);
+                if (!ret) {
+                    ret = decode_subblock(avctx, row, col + hbs, lflvl,
+                                          yoff + 8 * hbs, uvoff + 4 * hbs,
+                                          bl + 1);
+                    if (!ret) {
+                        yoff  += hbs * 8 * s->cur_frame->linesize[0];
+                        uvoff += hbs * 4 * s->cur_frame->linesize[1];
+                        ret    = decode_subblock(avctx, row + hbs, col, lflvl,
+                                                 yoff, uvoff, bl + 1);
+                        if (!ret) {
+                            ret = decode_subblock(avctx, row + hbs, col + hbs,
+                                                  lflvl, yoff + 8 * hbs,
+                                                  uvoff + 4 * hbs, bl + 1);
+                        }
+                    }
+                }
+                break;
+            default:
+                av_log(avctx, AV_LOG_ERROR, "Unexpected partition %d.", bp);
+                return AVERROR_INVALIDDATA;
+            }
+        } else if (vp56_rac_get_prob_branchy(&s->c, p[1])) {
+            bp  = PARTITION_SPLIT;
+            ret = decode_subblock(avctx, row, col, lflvl, yoff, uvoff, bl + 1);
+            if (!ret)
+                ret = decode_subblock(avctx, row, col + hbs, lflvl,
+                                      yoff + 8 * hbs, uvoff + 4 * hbs, bl + 1);
+        } else {
+            bp  = PARTITION_H;
+            ret = ff_vp9_decode_block(avctx, row, col, lflvl, yoff, uvoff,
+                                      bl, bp);
+        }
+    } else if (row + hbs < s->rows) {
+        if (vp56_rac_get_prob_branchy(&s->c, p[2])) {
+            bp  = PARTITION_SPLIT;
+            ret = decode_subblock(avctx, row, col, lflvl, yoff, uvoff, bl + 1);
+            if (!ret) {
+                yoff  += hbs * 8 * s->cur_frame->linesize[0];
+                uvoff += hbs * 4 * s->cur_frame->linesize[1];
+                ret    = decode_subblock(avctx, row + hbs, col, lflvl,
+                                         yoff, uvoff, bl + 1);
+            }
+        } else {
+            bp  = PARTITION_V;
+            ret = ff_vp9_decode_block(avctx, row, col, lflvl, yoff, uvoff,
+                                      bl, bp);
+        }
+    } else {
+        bp  = PARTITION_SPLIT;
+        ret = decode_subblock(avctx, row, col, lflvl, yoff, uvoff, bl + 1);
+    }
+    s->counts.partition[bl][c][bp]++;
+
+    return ret;
+}
+
+static void loopfilter_subblock(AVCodecContext *avctx, VP9Filter *lflvl,
+                                int row, int col,
+                                ptrdiff_t yoff, ptrdiff_t uvoff)
+{
+    VP9Context *s = avctx->priv_data;
+    uint8_t *dst   = s->cur_frame->data[0] + yoff, *lvl = lflvl->level;
+    ptrdiff_t ls_y = s->cur_frame->linesize[0], ls_uv = s->cur_frame->linesize[1];
+    int y, x, p;
+
+    /* FIXME: In how far can we interleave the v/h loopfilter calls? E.g.
+     * if you think of them as acting on a 8x8 block max, we can interleave
+     * each v/h within the single x loop, but that only works if we work on
+     * 8 pixel blocks, and we won't always do that (we want at least 16px
+     * to use SSE2 optimizations, perhaps 32 for AVX2). */
+
+    // filter edges between columns, Y plane (e.g. block1 | block2)
+    for (y = 0; y < 8; y += 2, dst += 16 * ls_y, lvl += 16) {
+        uint8_t *ptr = dst, *l = lvl, *hmask1 = lflvl->mask[0][0][y];
+        uint8_t *hmask2 = lflvl->mask[0][0][y + 1];
+        unsigned hm1 = hmask1[0] | hmask1[1] | hmask1[2], hm13 = hmask1[3];
+        unsigned hm2 = hmask2[1] | hmask2[2], hm23 = hmask2[3];
+        unsigned hm  = hm1 | hm2 | hm13 | hm23;
+
+        for (x = 1; hm & ~(x - 1); x <<= 1, ptr += 8, l++) {
+            if (hm1 & x) {
+                int L = *l, H = L >> 4;
+                int E = s->filter.mblim_lut[L], I = s->filter.lim_lut[L];
+
+                if (col || x > 1) {
+                    if (hmask1[0] & x) {
+                        if (hmask2[0] & x) {
+                            av_assert2(l[8] == L);
+                            s->dsp.loop_filter_16[0](ptr, ls_y, E, I, H);
+                        } else {
+                            s->dsp.loop_filter_8[2][0](ptr, ls_y, E, I, H);
+                        }
+                    } else if (hm2 & x) {
+                        L  = l[8];
+                        H |= (L >> 4) << 8;
+                        E |= s->filter.mblim_lut[L] << 8;
+                        I |= s->filter.lim_lut[L] << 8;
+                        s->dsp.loop_filter_mix2[!!(hmask1[1] & x)]
+                                               [!!(hmask2[1] & x)]
+                                               [0](ptr, ls_y, E, I, H);
+                    } else {
+                        s->dsp.loop_filter_8[!!(hmask1[1] & x)]
+                                            [0](ptr, ls_y, E, I, H);
+                    }
+                }
+            } else if (hm2 & x) {
+                int L = l[8], H = L >> 4;
+                int E = s->filter.mblim_lut[L], I = s->filter.lim_lut[L];
+
+                if (col || x > 1) {
+                    s->dsp.loop_filter_8[!!(hmask2[1] & x)]
+                                        [0](ptr + 8 * ls_y, ls_y, E, I, H);
+                }
+            }
+            if (hm13 & x) {
+                int L = *l, H = L >> 4;
+                int E = s->filter.mblim_lut[L], I = s->filter.lim_lut[L];
+
+                if (hm23 & x) {
+                    L  = l[8];
+                    H |= (L >> 4) << 8;
+                    E |= s->filter.mblim_lut[L] << 8;
+                    I |= s->filter.lim_lut[L] << 8;
+                    s->dsp.loop_filter_mix2[0][0][0](ptr + 4, ls_y, E, I, H);
+                } else {
+                    s->dsp.loop_filter_8[0][0](ptr + 4, ls_y, E, I, H);
+                }
+            } else if (hm23 & x) {
+                int L = l[8], H = L >> 4;
+                int E = s->filter.mblim_lut[L], I = s->filter.lim_lut[L];
+
+                s->dsp.loop_filter_8[0][0](ptr + 8 * ls_y + 4, ls_y, E, I, H);
+            }
+        }
+    }
+
+    //                                          block1
+    // filter edges between rows, Y plane (e.g. ------)
+    //                                          block2
+    dst = s->cur_frame->data[0] + yoff;
+    lvl = lflvl->level;
+    for (y = 0; y < 8; y++, dst += 8 * ls_y, lvl += 8) {
+        uint8_t *ptr = dst, *l = lvl, *vmask = lflvl->mask[0][1][y];
+        unsigned vm = vmask[0] | vmask[1] | vmask[2], vm3 = vmask[3];
+
+        for (x = 1; vm & ~(x - 1); x <<= 2, ptr += 16, l += 2) {
+            if (row || y) {
+                if (vm & x) {
+                    int L = *l, H = L >> 4;
+                    int E = s->filter.mblim_lut[L], I = s->filter.lim_lut[L];
+
+                    if (vmask[0] & x) {
+                        if (vmask[0] & (x << 1)) {
+                            av_assert2(l[1] == L);
+                            s->dsp.loop_filter_16[1](ptr, ls_y, E, I, H);
+                        } else {
+                            s->dsp.loop_filter_8[2][1](ptr, ls_y, E, I, H);
+                        }
+                    } else if (vm & (x << 1)) {
+                        L  = l[1];
+                        H |= (L >> 4) << 8;
+                        E |= s->filter.mblim_lut[L] << 8;
+                        I |= s->filter.lim_lut[L] << 8;
+                        s->dsp.loop_filter_mix2[!!(vmask[1] &  x)]
+                                               [!!(vmask[1] & (x << 1))]
+                                               [1](ptr, ls_y, E, I, H);
+                    } else {
+                        s->dsp.loop_filter_8[!!(vmask[1] & x)]
+                                            [1](ptr, ls_y, E, I, H);
+                    }
+                } else if (vm & (x << 1)) {
+                    int L = l[1], H = L >> 4;
+                    int E = s->filter.mblim_lut[L], I = s->filter.lim_lut[L];
+
+                    s->dsp.loop_filter_8[!!(vmask[1] & (x << 1))]
+                                        [1](ptr + 8, ls_y, E, I, H);
+                }
+            }
+            if (vm3 & x) {
+                int L = *l, H = L >> 4;
+                int E = s->filter.mblim_lut[L], I = s->filter.lim_lut[L];
+
+                if (vm3 & (x << 1)) {
+                    L  = l[1];
+                    H |= (L >> 4) << 8;
+                    E |= s->filter.mblim_lut[L] << 8;
+                    I |= s->filter.lim_lut[L] << 8;
+                    s->dsp.loop_filter_mix2[0][0][1](ptr + ls_y * 4, ls_y, E, I, H);
+                } else {
+                    s->dsp.loop_filter_8[0][1](ptr + ls_y * 4, ls_y, E, I, H);
+                }
+            } else if (vm3 & (x << 1)) {
+                int L = l[1], H = L >> 4;
+                int E = s->filter.mblim_lut[L], I = s->filter.lim_lut[L];
+
+                s->dsp.loop_filter_8[0][1](ptr + ls_y * 4 + 8, ls_y, E, I, H);
+            }
+        }
+    }
+
+    // same principle but for U/V planes
+    for (p = 0; p < 2; p++) {
+        lvl = lflvl->level;
+        dst = s->cur_frame->data[1 + p] + uvoff;
+        for (y = 0; y < 8; y += 4, dst += 16 * ls_uv, lvl += 32) {
+            uint8_t *ptr = dst, *l = lvl, *hmask1 = lflvl->mask[1][0][y];
+            uint8_t *hmask2 = lflvl->mask[1][0][y + 2];
+            unsigned hm1 = hmask1[0] | hmask1[1] | hmask1[2];
+            unsigned hm2 = hmask2[1] | hmask2[2], hm = hm1 | hm2;
+
+            for (x = 1; hm & ~(x - 1); x <<= 1, ptr += 4) {
+                if (col || x > 1) {
+                    if (hm1 & x) {
+                        int L = *l, H = L >> 4;
+                        int E = s->filter.mblim_lut[L];
+                        int I = s->filter.lim_lut[L];
+
+                        if (hmask1[0] & x) {
+                            if (hmask2[0] & x) {
+                                av_assert2(l[16] == L);
+                                s->dsp.loop_filter_16[0](ptr, ls_uv, E, I, H);
+                            } else {
+                                s->dsp.loop_filter_8[2][0](ptr, ls_uv, E, I, H);
+                            }
+                        } else if (hm2 & x) {
+                            L  = l[16];
+                            H |= (L >> 4) << 8;
+                            E |= s->filter.mblim_lut[L] << 8;
+                            I |= s->filter.lim_lut[L] << 8;
+                            s->dsp.loop_filter_mix2[!!(hmask1[1] & x)]
+                                                   [!!(hmask2[1] & x)]
+                                                   [0](ptr, ls_uv, E, I, H);
+                        } else {
+                            s->dsp.loop_filter_8[!!(hmask1[1] & x)]
+                                                [0](ptr, ls_uv, E, I, H);
+                        }
+                    } else if (hm2 & x) {
+                        int L = l[16], H = L >> 4;
+                        int E = s->filter.mblim_lut[L];
+                        int I = s->filter.lim_lut[L];
+
+                        s->dsp.loop_filter_8[!!(hmask2[1] & x)]
+                                            [0](ptr + 8 * ls_uv, ls_uv, E, I, H);
+                    }
+                }
+                if (x & 0xAA)
+                    l += 2;
+            }
+        }
+        lvl = lflvl->level;
+        dst = s->cur_frame->data[1 + p] + uvoff;
+        for (y = 0; y < 8; y++, dst += 4 * ls_uv) {
+            uint8_t *ptr = dst, *l = lvl, *vmask = lflvl->mask[1][1][y];
+            unsigned vm = vmask[0] | vmask[1] | vmask[2];
+
+            for (x = 1; vm & ~(x - 1); x <<= 4, ptr += 16, l += 4) {
+                if (row || y) {
+                    if (vm & x) {
+                        int L = *l, H = L >> 4;
+                        int E = s->filter.mblim_lut[L];
+                        int I = s->filter.lim_lut[L];
+
+                        if (vmask[0] & x) {
+                            if (vmask[0] & (x << 2)) {
+                                av_assert2(l[2] == L);
+                                s->dsp.loop_filter_16[1](ptr, ls_uv, E, I, H);
+                            } else {
+                                s->dsp.loop_filter_8[2][1](ptr, ls_uv, E, I, H);
+                            }
+                        } else if (vm & (x << 2)) {
+                            L  = l[2];
+                            H |= (L >> 4) << 8;
+                            E |= s->filter.mblim_lut[L] << 8;
+                            I |= s->filter.lim_lut[L] << 8;
+                            s->dsp.loop_filter_mix2[!!(vmask[1] &  x)]
+                                                   [!!(vmask[1] & (x << 2))]
+                                                   [1](ptr, ls_uv, E, I, H);
+                        } else {
+                            s->dsp.loop_filter_8[!!(vmask[1] & x)]
+                                                [1](ptr, ls_uv, E, I, H);
+                        }
+                    } else if (vm & (x << 2)) {
+                        int L = l[2], H = L >> 4;
+                        int E = s->filter.mblim_lut[L];
+                        int I = s->filter.lim_lut[L];
+
+                        s->dsp.loop_filter_8[!!(vmask[1] & (x << 2))]
+                                            [1](ptr + 8, ls_uv, E, I, H);
+                    }
+                }
+            }
+            if (y & 1)
+                lvl += 16;
+        }
+    }
+}
+
+static void set_tile_offset(int *start, int *end, int idx, int log2_n, int n)
+{
+    int sb_start =  (idx      * n) >> log2_n;
+    int sb_end   = ((idx + 1) * n) >> log2_n;
+    *start = FFMIN(sb_start, n) << 3;
+    *end   = FFMIN(sb_end,   n) << 3;
+}
+
+static int vp9_decode_frame(AVCodecContext *avctx, AVFrame *frame,
+                            int *got_frame, const uint8_t *data, int size)
+{
+    VP9Context *s = avctx->priv_data;
+    int ret, tile_row, tile_col, i, ref = -1, row, col;
+    ptrdiff_t yoff = 0, uvoff = 0;
+
+    ret = decode_frame_header(avctx, data, size, &ref);
+    if (ret < 0) {
+        return ret;
+    } else if (!ret) {
+        if (!s->refs[ref]->buf[0]) {
+            av_log(avctx, AV_LOG_ERROR,
+                   "Requested reference %d not available\n", ref);
+            return AVERROR_INVALIDDATA;
+        }
+
+        ret = av_frame_ref(frame, s->refs[ref]);
+        if (ret < 0)
+            return ret;
+        *got_frame = 1;
+        return 0;
+    }
+    data += ret;
+    size -= ret;
+
+    s->cur_frame = frame;
+
+    av_frame_unref(s->cur_frame);
+    if ((ret = ff_get_buffer(avctx, s->cur_frame,
+                             s->refreshrefmask ? AV_GET_BUFFER_FLAG_REF : 0)) < 0)
+        return ret;
+    s->cur_frame->key_frame = s->keyframe;
+    s->cur_frame->pict_type = s->keyframe ? AV_PICTURE_TYPE_I
+                                          : AV_PICTURE_TYPE_P;
+
+    // main tile decode loop
+    memset(s->above_partition_ctx, 0, s->cols);
+    memset(s->above_skip_ctx, 0, s->cols);
+    if (s->keyframe || s->intraonly)
+        memset(s->above_mode_ctx, DC_PRED, s->cols * 2);
+    else
+        memset(s->above_mode_ctx, NEARESTMV, s->cols);
+    memset(s->above_y_nnz_ctx, 0, s->sb_cols * 16);
+    memset(s->above_uv_nnz_ctx[0], 0, s->sb_cols * 8);
+    memset(s->above_uv_nnz_ctx[1], 0, s->sb_cols * 8);
+    memset(s->above_segpred_ctx, 0, s->cols);
+    for (tile_row = 0; tile_row < s->tiling.tile_rows; tile_row++) {
+        set_tile_offset(&s->tiling.tile_row_start, &s->tiling.tile_row_end,
+                        tile_row, s->tiling.log2_tile_rows, s->sb_rows);
+        for (tile_col = 0; tile_col < s->tiling.tile_cols; tile_col++) {
+            int64_t tile_size;
+
+            if (tile_col == s->tiling.tile_cols - 1 &&
+                tile_row == s->tiling.tile_rows - 1) {
+                tile_size = size;
+            } else {
+                tile_size = AV_RB32(data);
+                data     += 4;
+                size     -= 4;
+            }
+            if (tile_size > size)
+                return AVERROR_INVALIDDATA;
+            ff_vp56_init_range_decoder(&s->c_b[tile_col], data, tile_size);
+            if (vp56_rac_get_prob_branchy(&s->c_b[tile_col], 128)) // marker bit
+                return AVERROR_INVALIDDATA;
+            data += tile_size;
+            size -= tile_size;
+        }
+
+        for (row = s->tiling.tile_row_start;
+             row < s->tiling.tile_row_end;
+             row += 8, yoff += s->cur_frame->linesize[0] * 64,
+             uvoff += s->cur_frame->linesize[1] * 32) {
+            VP9Filter *lflvl = s->lflvl;
+            ptrdiff_t yoff2 = yoff, uvoff2 = uvoff;
+
+            for (tile_col = 0; tile_col < s->tiling.tile_cols; tile_col++) {
+                set_tile_offset(&s->tiling.tile_col_start,
+                                &s->tiling.tile_col_end,
+                                tile_col, s->tiling.log2_tile_cols, s->sb_cols);
+
+                memset(s->left_partition_ctx, 0, 8);
+                memset(s->left_skip_ctx, 0, 8);
+                if (s->keyframe || s->intraonly)
+                    memset(s->left_mode_ctx, DC_PRED, 16);
+                else
+                    memset(s->left_mode_ctx, NEARESTMV, 8);
+                memset(s->left_y_nnz_ctx, 0, 16);
+                memset(s->left_uv_nnz_ctx, 0, 16);
+                memset(s->left_segpred_ctx, 0, 8);
+
+                memcpy(&s->c, &s->c_b[tile_col], sizeof(s->c));
+                for (col = s->tiling.tile_col_start;
+                     col < s->tiling.tile_col_end;
+                     col += 8, yoff2 += 64, uvoff2 += 32, lflvl++) {
+                    // FIXME integrate with lf code (i.e. zero after each
+                    // use, similar to invtxfm coefficients, or similar)
+                    memset(lflvl->mask, 0, sizeof(lflvl->mask));
+
+                    if ((ret = decode_subblock(avctx, row, col, lflvl,
+                                               yoff2, uvoff2, BL_64X64)) < 0)
+                        return ret;
+                }
+                memcpy(&s->c_b[tile_col], &s->c, sizeof(s->c));
+            }
+
+            // backup pre-loopfilter reconstruction data for intra
+            // prediction of next row of sb64s
+            if (row + 8 < s->rows) {
+                memcpy(s->intra_pred_data[0],
+                       s->cur_frame->data[0] + yoff +
+                       63 * s->cur_frame->linesize[0],
+                       8 * s->cols);
+                memcpy(s->intra_pred_data[1],
+                       s->cur_frame->data[1] + uvoff +
+                       31 * s->cur_frame->linesize[1],
+                       4 * s->cols);
+                memcpy(s->intra_pred_data[2],
+                       s->cur_frame->data[2] + uvoff +
+                       31 * s->cur_frame->linesize[2],
+                       4 * s->cols);
+            }
+
+            // loopfilter one row
+            if (s->filter.level) {
+                yoff2  = yoff;
+                uvoff2 = uvoff;
+                lflvl  = s->lflvl;
+                for (col = 0; col < s->cols;
+                     col += 8, yoff2 += 64, uvoff2 += 32, lflvl++)
+                    loopfilter_subblock(avctx, lflvl, row, col, yoff2, uvoff2);
+            }
+        }
+    }
+
+    // bw adaptivity (or in case of parallel decoding mode, fw adaptivity
+    // probability maintenance between frames)
+    if (s->refreshctx) {
+        if (s->parallelmode) {
+            memcpy(s->prob_ctx[s->framectxid].coef, s->prob.coef,
+                   sizeof(s->prob.coef));
+            s->prob_ctx[s->framectxid].p = s->prob.p;
+        } else {
+            ff_vp9_adapt_probs(s);
+        }
+    }
+    FFSWAP(VP9MVRefPair *, s->mv[0], s->mv[1]);
+
+    // ref frame setup
+    for (i = 0; i < 8; i++)
+        if (s->refreshrefmask & (1 << i)) {
+            av_frame_unref(s->refs[i]);
+            ret = av_frame_ref(s->refs[i], s->cur_frame);
+            if (ret < 0)
+                return ret;
+        }
+
+    if (s->invisible)
+        av_frame_unref(s->cur_frame);
+    else
+        *got_frame = 1;
+
+    return 0;
+}
+
+static int vp9_decode_packet(AVCodecContext *avctx, void *frame,
+                             int *got_frame, AVPacket *avpkt)
+{
+    const uint8_t *data = avpkt->data;
+    int size            = avpkt->size;
+    int marker, ret;
+
+    /* Read superframe index - this is a collection of individual frames
+     * that together lead to one visible frame */
+    marker = data[size - 1];
+    if ((marker & 0xe0) == 0xc0) {
+        int nbytes   = 1 + ((marker >> 3) & 0x3);
+        int n_frames = 1 + (marker & 0x7);
+        int idx_sz   = 2 + n_frames * nbytes;
+
+        if (size >= idx_sz && data[size - idx_sz] == marker) {
+            const uint8_t *idx = data + size + 1 - idx_sz;
+
+            while (n_frames--) {
+                int sz = AV_RL32(idx);
+
+                if (nbytes < 4)
+                    sz &= (1 << (8 * nbytes)) - 1;
+                idx += nbytes;
+
+                if (sz > size) {
+                    av_log(avctx, AV_LOG_ERROR,
+                           "Superframe packet size too big: %d > %d\n",
+                           sz, size);
+                    return AVERROR_INVALIDDATA;
+                }
+
+                ret = vp9_decode_frame(avctx, frame, got_frame, data, sz);
+                if (ret < 0)
+                    return ret;
+                data += sz;
+                size -= sz;
+            }
+            return size;
+        }
+    }
+
+    /* If we get here, there was no valid superframe index, i.e. this is just
+     * one whole single frame. Decode it as such from the complete input buf. */
+    if ((ret = vp9_decode_frame(avctx, frame, got_frame, data, size)) < 0)
+        return ret;
+    return size;
+}
+
+static av_cold int vp9_decode_free(AVCodecContext *avctx)
+{
+    VP9Context *s = avctx->priv_data;
+    int i;
+
+    for (i = 0; i < FF_ARRAY_ELEMS(s->refs); i++)
+        av_frame_free(&s->refs[i]);
+
+    av_freep(&s->c_b);
+    av_freep(&s->above_partition_ctx);
+
+    return 0;
+}
+
+static av_cold int vp9_decode_init(AVCodecContext *avctx)
+{
+    VP9Context *s = avctx->priv_data;
+    int i;
+
+    avctx->pix_fmt = AV_PIX_FMT_YUV420P;
+
+    ff_vp9dsp_init(&s->dsp);
+    ff_videodsp_init(&s->vdsp, 8);
+
+    for (i = 0; i < FF_ARRAY_ELEMS(s->refs); i++) {
+        s->refs[i] = av_frame_alloc();
+        if (!s->refs[i]) {
+            vp9_decode_free(avctx);
+            return AVERROR(ENOMEM);
+        }
+    }
+
+    s->filter.sharpness = -1;
+
+    return 0;
+}
+
+AVCodec ff_vp9_decoder = {
+    .name           = "vp9",
+    .long_name      = NULL_IF_CONFIG_SMALL("Google VP9"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_VP9,
+    .priv_data_size = sizeof(VP9Context),
+    .init           = vp9_decode_init,
+    .decode         = vp9_decode_packet,
+    .flush          = vp9_decode_flush,
+    .close          = vp9_decode_free,
+    .capabilities   = CODEC_CAP_DR1,
+};