vp56.h 10.3 KB
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/*
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 * Copyright (C) 2006  Aurelien Jacobs <aurel@gnuage.org>
 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * 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.
 *
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 * Libav is distributed in the hope that it will be useful,
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 * 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
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */

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/**
 * @file
 * VP5 and VP6 compatible video decoder (common features)
 */

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#ifndef AVCODEC_VP56_H
#define AVCODEC_VP56_H
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#include "vp56data.h"
#include "dsputil.h"
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#include "get_bits.h"
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#include "bytestream.h"
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#include "vp3dsp.h"
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#include "vp56dsp.h"
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typedef struct vp56_context VP56Context;
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typedef struct VP56mv {
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    DECLARE_ALIGNED(4, int16_t, x);
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    int16_t y;
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} VP56mv;
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typedef void (*VP56ParseVectorAdjustment)(VP56Context *s,
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                                          VP56mv *vect);
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typedef void (*VP56Filter)(VP56Context *s, uint8_t *dst, uint8_t *src,
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                           int offset1, int offset2, int stride,
                           VP56mv mv, int mask, int select, int luma);
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typedef void (*VP56ParseCoeff)(VP56Context *s);
typedef void (*VP56DefaultModelsInit)(VP56Context *s);
typedef void (*VP56ParseVectorModels)(VP56Context *s);
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typedef int  (*VP56ParseCoeffModels)(VP56Context *s);
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typedef int  (*VP56ParseHeader)(VP56Context *s, const uint8_t *buf,
                                int buf_size, int *golden_frame);
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typedef struct VP56RangeCoder {
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    int high;
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    int bits; /* stored negated (i.e. negative "bits" is a positive number of
                 bits left) in order to eliminate a negate in cache refilling */
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    const uint8_t *buffer;
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    const uint8_t *end;
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    unsigned int code_word;
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} VP56RangeCoder;
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typedef struct VP56RefDc {
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    uint8_t not_null_dc;
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    VP56Frame ref_frame;
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    DCTELEM dc_coeff;
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} VP56RefDc;
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typedef struct VP56Macroblock {
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    uint8_t type;
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    VP56mv mv;
} VP56Macroblock;
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typedef struct VP56Model {
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    uint8_t coeff_reorder[64];       /* used in vp6 only */
    uint8_t coeff_index_to_pos[64];  /* used in vp6 only */
    uint8_t vector_sig[2];           /* delta sign */
    uint8_t vector_dct[2];           /* delta coding types */
    uint8_t vector_pdi[2][2];        /* predefined delta init */
    uint8_t vector_pdv[2][7];        /* predefined delta values */
    uint8_t vector_fdv[2][8];        /* 8 bit delta value definition */
    uint8_t coeff_dccv[2][11];       /* DC coeff value */
    uint8_t coeff_ract[2][3][6][11]; /* Run/AC coding type and AC coeff value */
    uint8_t coeff_acct[2][3][3][6][5];/* vp5 only AC coding type for coding group < 3 */
    uint8_t coeff_dcct[2][36][5];    /* DC coeff coding type */
    uint8_t coeff_runv[2][14];       /* run value (vp6 only) */
    uint8_t mb_type[3][10][10];      /* model for decoding MB type */
    uint8_t mb_types_stats[3][10][2];/* contextual, next MB type stats */
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} VP56Model;
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struct vp56_context {
    AVCodecContext *avctx;
    DSPContext dsp;
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    VP3DSPContext vp3dsp;
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    VP56DSPContext vp56dsp;
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    ScanTable scantable;
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    AVFrame frames[4];
    AVFrame *framep[6];
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    uint8_t *edge_emu_buffer_alloc;
    uint8_t *edge_emu_buffer;
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    VP56RangeCoder c;
    VP56RangeCoder cc;
    VP56RangeCoder *ccp;
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    int sub_version;
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    /* frame info */
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    int plane_width[4];
    int plane_height[4];
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    int mb_width;   /* number of horizontal MB */
    int mb_height;  /* number of vertical MB */
    int block_offset[6];

    int quantizer;
    uint16_t dequant_dc;
    uint16_t dequant_ac;
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    int8_t *qscale_table;
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    /* DC predictors management */
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    VP56RefDc *above_blocks;
    VP56RefDc left_block[4];
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    int above_block_idx[6];
    DCTELEM prev_dc[3][3];    /* [plan][ref_frame] */

    /* blocks / macroblock */
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    VP56mb mb_type;
    VP56Macroblock *macroblocks;
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    DECLARE_ALIGNED(16, DCTELEM, block_coeff)[6][64];
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    /* motion vectors */
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    VP56mv mv[6];  /* vectors for each block in MB */
    VP56mv vector_candidate[2];
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    int vector_candidate_pos;

    /* filtering hints */
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    int filter_header;               /* used in vp6 only */
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    int deblock_filtering;
    int filter_selection;
    int filter_mode;
    int max_vector_length;
    int sample_variance_threshold;

    uint8_t coeff_ctx[4][64];              /* used in vp5 only */
    uint8_t coeff_ctx_last[4];             /* used in vp5 only */

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    int has_alpha;

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    /* upside-down flipping hints */
    int flip;  /* are we flipping ? */
    int frbi;  /* first row block index in MB */
    int srbi;  /* second row block index in MB */
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    int stride[4];  /* stride for each plan */
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    const uint8_t *vp56_coord_div;
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    VP56ParseVectorAdjustment parse_vector_adjustment;
    VP56Filter filter;
    VP56ParseCoeff parse_coeff;
    VP56DefaultModelsInit default_models_init;
    VP56ParseVectorModels parse_vector_models;
    VP56ParseCoeffModels parse_coeff_models;
    VP56ParseHeader parse_header;

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    VP56Model *modelp;
    VP56Model models[2];
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    /* huffman decoding */
    int use_huffman;
    GetBitContext gb;
    VLC dccv_vlc[2];
    VLC runv_vlc[2];
    VLC ract_vlc[2][3][6];
    unsigned int nb_null[2][2];       /* number of consecutive NULL DC/AC */
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};


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void ff_vp56_init(AVCodecContext *avctx, int flip, int has_alpha);
int ff_vp56_free(AVCodecContext *avctx);
void ff_vp56_init_dequant(VP56Context *s, int quantizer);
int ff_vp56_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
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                         AVPacket *avpkt);
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/**
 * vp56 specific range coder implementation
 */

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extern const uint8_t ff_vp56_norm_shift[256];
void ff_vp56_init_range_decoder(VP56RangeCoder *c, const uint8_t *buf, int buf_size);
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static av_always_inline unsigned int vp56_rac_renorm(VP56RangeCoder *c)
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{
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    int shift = ff_vp56_norm_shift[c->high];
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    int bits = c->bits;
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    unsigned int code_word = c->code_word;
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    c->high   <<= shift;
    code_word <<= shift;
    bits       += shift;
    if(bits >= 0 && c->buffer < c->end) {
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        code_word |= bytestream_get_be16(&c->buffer) << bits;
        bits -= 16;
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    }
    c->bits = bits;
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    return code_word;
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}

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#if   ARCH_ARM
#include "arm/vp56_arith.h"
#elif ARCH_X86
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#include "x86/vp56_arith.h"
#endif

#ifndef vp56_rac_get_prob
#define vp56_rac_get_prob vp56_rac_get_prob
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static av_always_inline int vp56_rac_get_prob(VP56RangeCoder *c, uint8_t prob)
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{
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    unsigned int code_word = vp56_rac_renorm(c);
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    unsigned int low = 1 + (((c->high - 1) * prob) >> 8);
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    unsigned int low_shift = low << 16;
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    int bit = code_word >= low_shift;
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    c->high = bit ? c->high - low : low;
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    c->code_word = bit ? code_word - low_shift : code_word;
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    return bit;
}
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#endif
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#ifndef vp56_rac_get_prob_branchy
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// branchy variant, to be used where there's a branch based on the bit decoded
static av_always_inline int vp56_rac_get_prob_branchy(VP56RangeCoder *c, int prob)
{
    unsigned long code_word = vp56_rac_renorm(c);
    unsigned low = 1 + (((c->high - 1) * prob) >> 8);
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    unsigned low_shift = low << 16;
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    if (code_word >= low_shift) {
        c->high     -= low;
        c->code_word = code_word - low_shift;
        return 1;
    }

    c->high = low;
    c->code_word = code_word;
    return 0;
}
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#endif
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static av_always_inline int vp56_rac_get(VP56RangeCoder *c)
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{
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    unsigned int code_word = vp56_rac_renorm(c);
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    /* equiprobable */
    int low = (c->high + 1) >> 1;
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    unsigned int low_shift = low << 16;
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    int bit = code_word >= low_shift;
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    if (bit) {
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        c->high   -= low;
        code_word -= low_shift;
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    } else {
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        c->high = low;
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    }

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    c->code_word = code_word;
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    return bit;
}

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// rounding is different than vp56_rac_get, is vp56_rac_get wrong?
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static av_always_inline int vp8_rac_get(VP56RangeCoder *c)
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{
    return vp56_rac_get_prob(c, 128);
}

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static av_unused int vp56_rac_gets(VP56RangeCoder *c, int bits)
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{
    int value = 0;

    while (bits--) {
        value = (value << 1) | vp56_rac_get(c);
    }

    return value;
}

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static av_unused int vp8_rac_get_uint(VP56RangeCoder *c, int bits)
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{
    int value = 0;

    while (bits--) {
        value = (value << 1) | vp8_rac_get(c);
    }

    return value;
}

// fixme: add 1 bit to all the calls to this?
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static av_unused int vp8_rac_get_sint(VP56RangeCoder *c, int bits)
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{
    int v;

    if (!vp8_rac_get(c))
        return 0;

    v = vp8_rac_get_uint(c, bits);

    if (vp8_rac_get(c))
        v = -v;

    return v;
}

// P(7)
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static av_unused int vp56_rac_gets_nn(VP56RangeCoder *c, int bits)
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{
    int v = vp56_rac_gets(c, 7) << 1;
    return v + !v;
}

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static av_unused int vp8_rac_get_nn(VP56RangeCoder *c)
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{
    int v = vp8_rac_get_uint(c, 7) << 1;
    return v + !v;
}

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static av_always_inline
int vp56_rac_get_tree(VP56RangeCoder *c,
                      const VP56Tree *tree,
                      const uint8_t *probs)
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{
    while (tree->val > 0) {
        if (vp56_rac_get_prob(c, probs[tree->prob_idx]))
            tree += tree->val;
        else
            tree++;
    }
    return -tree->val;
}

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/**
 * This is identical to vp8_rac_get_tree except for the possibility of starting
 * on a node other than the root node, needed for coeff decode where this is
 * used to save a bit after a 0 token (by disallowing EOB to immediately follow.)
 */
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static av_always_inline
int vp8_rac_get_tree_with_offset(VP56RangeCoder *c, const int8_t (*tree)[2],
                                 const uint8_t *probs, int i)
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{
    do {
        i = tree[i][vp56_rac_get_prob(c, probs[i])];
    } while (i > 0);

    return -i;
}

// how probabilities are associated with decisions is different I think
// well, the new scheme fits in the old but this way has one fewer branches per decision
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static av_always_inline
int vp8_rac_get_tree(VP56RangeCoder *c, const int8_t (*tree)[2],
                     const uint8_t *probs)
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{
    return vp8_rac_get_tree_with_offset(c, tree, probs, 0);
}

// DCTextra
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static av_always_inline int vp8_rac_get_coeff(VP56RangeCoder *c, const uint8_t *prob)
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{
    int v = 0;

    do {
        v = (v<<1) + vp56_rac_get_prob(c, *prob++);
    } while (*prob);

    return v;
}

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#endif /* AVCODEC_VP56_H */