go-libwebp

Experimental translation from libwebp to Go source.
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tree_dec.c (23658B)


      1 // Copyright 2010 Google Inc. All Rights Reserved.
      2 //
      3 // Use of this source code is governed by a BSD-style license
      4 // that can be found in the COPYING file in the root of the source
      5 // tree. An additional intellectual property rights grant can be found
      6 // in the file PATENTS. All contributing project authors may
      7 // be found in the AUTHORS file in the root of the source tree.
      8 // -----------------------------------------------------------------------------
      9 //
     10 // Coding trees and probas
     11 //
     12 // Author: Skal (pascal.massimino@gmail.com)
     13 
     14 #include <string.h>
     15 
     16 #include "src/dec/common_dec.h"
     17 #include "src/webp/types.h"
     18 #include "src/dec/vp8_dec.h"
     19 #include "src/dec/vp8i_dec.h"
     20 #include "src/dsp/cpu.h"
     21 #include "src/utils/bit_reader_inl_utils.h"
     22 #include "src/utils/bit_reader_utils.h"
     23 
     24 #if !defined(USE_GENERIC_TREE)
     25 #if !defined(__arm__) && !defined(_M_ARM) && !WEBP_AARCH64 && \
     26     !defined(__wasm__)
     27 // using a table is ~1-2% slower on ARM. Prefer the coded-tree approach then.
     28 #define USE_GENERIC_TREE 1   // ALTERNATE_CODE
     29 #else
     30 #define USE_GENERIC_TREE 0
     31 #endif
     32 #endif  // USE_GENERIC_TREE
     33 
     34 #if (USE_GENERIC_TREE == 1)
     35 static const int8_t kYModesIntra4[18] = {
     36   -B_DC_PRED, 1,
     37     -B_TM_PRED, 2,
     38       -B_VE_PRED, 3,
     39         4, 6,
     40           -B_HE_PRED, 5,
     41             -B_RD_PRED, -B_VR_PRED,
     42         -B_LD_PRED, 7,
     43           -B_VL_PRED, 8,
     44             -B_HD_PRED, -B_HU_PRED
     45 };
     46 #endif
     47 
     48 //------------------------------------------------------------------------------
     49 // Default probabilities
     50 
     51 // Paragraph 13.5
     52 static const uint8_t
     53   CoeffsProba0[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS] = {
     54   { { { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
     55       { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
     56       { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
     57     },
     58     { { 253, 136, 254, 255, 228, 219, 128, 128, 128, 128, 128 },
     59       { 189, 129, 242, 255, 227, 213, 255, 219, 128, 128, 128 },
     60       { 106, 126, 227, 252, 214, 209, 255, 255, 128, 128, 128 }
     61     },
     62     { { 1, 98, 248, 255, 236, 226, 255, 255, 128, 128, 128 },
     63       { 181, 133, 238, 254, 221, 234, 255, 154, 128, 128, 128 },
     64       { 78, 134, 202, 247, 198, 180, 255, 219, 128, 128, 128 },
     65     },
     66     { { 1, 185, 249, 255, 243, 255, 128, 128, 128, 128, 128 },
     67       { 184, 150, 247, 255, 236, 224, 128, 128, 128, 128, 128 },
     68       { 77, 110, 216, 255, 236, 230, 128, 128, 128, 128, 128 },
     69     },
     70     { { 1, 101, 251, 255, 241, 255, 128, 128, 128, 128, 128 },
     71       { 170, 139, 241, 252, 236, 209, 255, 255, 128, 128, 128 },
     72       { 37, 116, 196, 243, 228, 255, 255, 255, 128, 128, 128 }
     73     },
     74     { { 1, 204, 254, 255, 245, 255, 128, 128, 128, 128, 128 },
     75       { 207, 160, 250, 255, 238, 128, 128, 128, 128, 128, 128 },
     76       { 102, 103, 231, 255, 211, 171, 128, 128, 128, 128, 128 }
     77     },
     78     { { 1, 152, 252, 255, 240, 255, 128, 128, 128, 128, 128 },
     79       { 177, 135, 243, 255, 234, 225, 128, 128, 128, 128, 128 },
     80       { 80, 129, 211, 255, 194, 224, 128, 128, 128, 128, 128 }
     81     },
     82     { { 1, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
     83       { 246, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
     84       { 255, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
     85     }
     86   },
     87   { { { 198, 35, 237, 223, 193, 187, 162, 160, 145, 155, 62 },
     88       { 131, 45, 198, 221, 172, 176, 220, 157, 252, 221, 1 },
     89       { 68, 47, 146, 208, 149, 167, 221, 162, 255, 223, 128 }
     90     },
     91     { { 1, 149, 241, 255, 221, 224, 255, 255, 128, 128, 128 },
     92       { 184, 141, 234, 253, 222, 220, 255, 199, 128, 128, 128 },
     93       { 81, 99, 181, 242, 176, 190, 249, 202, 255, 255, 128 }
     94     },
     95     { { 1, 129, 232, 253, 214, 197, 242, 196, 255, 255, 128 },
     96       { 99, 121, 210, 250, 201, 198, 255, 202, 128, 128, 128 },
     97       { 23, 91, 163, 242, 170, 187, 247, 210, 255, 255, 128 }
     98     },
     99     { { 1, 200, 246, 255, 234, 255, 128, 128, 128, 128, 128 },
    100       { 109, 178, 241, 255, 231, 245, 255, 255, 128, 128, 128 },
    101       { 44, 130, 201, 253, 205, 192, 255, 255, 128, 128, 128 }
    102     },
    103     { { 1, 132, 239, 251, 219, 209, 255, 165, 128, 128, 128 },
    104       { 94, 136, 225, 251, 218, 190, 255, 255, 128, 128, 128 },
    105       { 22, 100, 174, 245, 186, 161, 255, 199, 128, 128, 128 }
    106     },
    107     { { 1, 182, 249, 255, 232, 235, 128, 128, 128, 128, 128 },
    108       { 124, 143, 241, 255, 227, 234, 128, 128, 128, 128, 128 },
    109       { 35, 77, 181, 251, 193, 211, 255, 205, 128, 128, 128 }
    110     },
    111     { { 1, 157, 247, 255, 236, 231, 255, 255, 128, 128, 128 },
    112       { 121, 141, 235, 255, 225, 227, 255, 255, 128, 128, 128 },
    113       { 45, 99, 188, 251, 195, 217, 255, 224, 128, 128, 128 }
    114     },
    115     { { 1, 1, 251, 255, 213, 255, 128, 128, 128, 128, 128 },
    116       { 203, 1, 248, 255, 255, 128, 128, 128, 128, 128, 128 },
    117       { 137, 1, 177, 255, 224, 255, 128, 128, 128, 128, 128 }
    118     }
    119   },
    120   { { { 253, 9, 248, 251, 207, 208, 255, 192, 128, 128, 128 },
    121       { 175, 13, 224, 243, 193, 185, 249, 198, 255, 255, 128 },
    122       { 73, 17, 171, 221, 161, 179, 236, 167, 255, 234, 128 }
    123     },
    124     { { 1, 95, 247, 253, 212, 183, 255, 255, 128, 128, 128 },
    125       { 239, 90, 244, 250, 211, 209, 255, 255, 128, 128, 128 },
    126       { 155, 77, 195, 248, 188, 195, 255, 255, 128, 128, 128 }
    127     },
    128     { { 1, 24, 239, 251, 218, 219, 255, 205, 128, 128, 128 },
    129       { 201, 51, 219, 255, 196, 186, 128, 128, 128, 128, 128 },
    130       { 69, 46, 190, 239, 201, 218, 255, 228, 128, 128, 128 }
    131     },
    132     { { 1, 191, 251, 255, 255, 128, 128, 128, 128, 128, 128 },
    133       { 223, 165, 249, 255, 213, 255, 128, 128, 128, 128, 128 },
    134       { 141, 124, 248, 255, 255, 128, 128, 128, 128, 128, 128 }
    135     },
    136     { { 1, 16, 248, 255, 255, 128, 128, 128, 128, 128, 128 },
    137       { 190, 36, 230, 255, 236, 255, 128, 128, 128, 128, 128 },
    138       { 149, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
    139     },
    140     { { 1, 226, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
    141       { 247, 192, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
    142       { 240, 128, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
    143     },
    144     { { 1, 134, 252, 255, 255, 128, 128, 128, 128, 128, 128 },
    145       { 213, 62, 250, 255, 255, 128, 128, 128, 128, 128, 128 },
    146       { 55, 93, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
    147     },
    148     { { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
    149       { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 },
    150       { 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128 }
    151     }
    152   },
    153   { { { 202, 24, 213, 235, 186, 191, 220, 160, 240, 175, 255 },
    154       { 126, 38, 182, 232, 169, 184, 228, 174, 255, 187, 128 },
    155       { 61, 46, 138, 219, 151, 178, 240, 170, 255, 216, 128 }
    156     },
    157     { { 1, 112, 230, 250, 199, 191, 247, 159, 255, 255, 128 },
    158       { 166, 109, 228, 252, 211, 215, 255, 174, 128, 128, 128 },
    159       { 39, 77, 162, 232, 172, 180, 245, 178, 255, 255, 128 }
    160     },
    161     { { 1, 52, 220, 246, 198, 199, 249, 220, 255, 255, 128 },
    162       { 124, 74, 191, 243, 183, 193, 250, 221, 255, 255, 128 },
    163       { 24, 71, 130, 219, 154, 170, 243, 182, 255, 255, 128 }
    164     },
    165     { { 1, 182, 225, 249, 219, 240, 255, 224, 128, 128, 128 },
    166       { 149, 150, 226, 252, 216, 205, 255, 171, 128, 128, 128 },
    167       { 28, 108, 170, 242, 183, 194, 254, 223, 255, 255, 128 }
    168     },
    169     { { 1, 81, 230, 252, 204, 203, 255, 192, 128, 128, 128 },
    170       { 123, 102, 209, 247, 188, 196, 255, 233, 128, 128, 128 },
    171       { 20, 95, 153, 243, 164, 173, 255, 203, 128, 128, 128 }
    172     },
    173     { { 1, 222, 248, 255, 216, 213, 128, 128, 128, 128, 128 },
    174       { 168, 175, 246, 252, 235, 205, 255, 255, 128, 128, 128 },
    175       { 47, 116, 215, 255, 211, 212, 255, 255, 128, 128, 128 }
    176     },
    177     { { 1, 121, 236, 253, 212, 214, 255, 255, 128, 128, 128 },
    178       { 141, 84, 213, 252, 201, 202, 255, 219, 128, 128, 128 },
    179       { 42, 80, 160, 240, 162, 185, 255, 205, 128, 128, 128 }
    180     },
    181     { { 1, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
    182       { 244, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 },
    183       { 238, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128 }
    184     }
    185   }
    186 };
    187 
    188 // Paragraph 11.5
    189 static const uint8_t kBModesProba[NUM_BMODES][NUM_BMODES][NUM_BMODES - 1] = {
    190   { { 231, 120, 48, 89, 115, 113, 120, 152, 112 },
    191     { 152, 179, 64, 126, 170, 118, 46, 70, 95 },
    192     { 175, 69, 143, 80, 85, 82, 72, 155, 103 },
    193     { 56, 58, 10, 171, 218, 189, 17, 13, 152 },
    194     { 114, 26, 17, 163, 44, 195, 21, 10, 173 },
    195     { 121, 24, 80, 195, 26, 62, 44, 64, 85 },
    196     { 144, 71, 10, 38, 171, 213, 144, 34, 26 },
    197     { 170, 46, 55, 19, 136, 160, 33, 206, 71 },
    198     { 63, 20, 8, 114, 114, 208, 12, 9, 226 },
    199     { 81, 40, 11, 96, 182, 84, 29, 16, 36 } },
    200   { { 134, 183, 89, 137, 98, 101, 106, 165, 148 },
    201     { 72, 187, 100, 130, 157, 111, 32, 75, 80 },
    202     { 66, 102, 167, 99, 74, 62, 40, 234, 128 },
    203     { 41, 53, 9, 178, 241, 141, 26, 8, 107 },
    204     { 74, 43, 26, 146, 73, 166, 49, 23, 157 },
    205     { 65, 38, 105, 160, 51, 52, 31, 115, 128 },
    206     { 104, 79, 12, 27, 217, 255, 87, 17, 7 },
    207     { 87, 68, 71, 44, 114, 51, 15, 186, 23 },
    208     { 47, 41, 14, 110, 182, 183, 21, 17, 194 },
    209     { 66, 45, 25, 102, 197, 189, 23, 18, 22 } },
    210   { { 88, 88, 147, 150, 42, 46, 45, 196, 205 },
    211     { 43, 97, 183, 117, 85, 38, 35, 179, 61 },
    212     { 39, 53, 200, 87, 26, 21, 43, 232, 171 },
    213     { 56, 34, 51, 104, 114, 102, 29, 93, 77 },
    214     { 39, 28, 85, 171, 58, 165, 90, 98, 64 },
    215     { 34, 22, 116, 206, 23, 34, 43, 166, 73 },
    216     { 107, 54, 32, 26, 51, 1, 81, 43, 31 },
    217     { 68, 25, 106, 22, 64, 171, 36, 225, 114 },
    218     { 34, 19, 21, 102, 132, 188, 16, 76, 124 },
    219     { 62, 18, 78, 95, 85, 57, 50, 48, 51 } },
    220   { { 193, 101, 35, 159, 215, 111, 89, 46, 111 },
    221     { 60, 148, 31, 172, 219, 228, 21, 18, 111 },
    222     { 112, 113, 77, 85, 179, 255, 38, 120, 114 },
    223     { 40, 42, 1, 196, 245, 209, 10, 25, 109 },
    224     { 88, 43, 29, 140, 166, 213, 37, 43, 154 },
    225     { 61, 63, 30, 155, 67, 45, 68, 1, 209 },
    226     { 100, 80, 8, 43, 154, 1, 51, 26, 71 },
    227     { 142, 78, 78, 16, 255, 128, 34, 197, 171 },
    228     { 41, 40, 5, 102, 211, 183, 4, 1, 221 },
    229     { 51, 50, 17, 168, 209, 192, 23, 25, 82 } },
    230   { { 138, 31, 36, 171, 27, 166, 38, 44, 229 },
    231     { 67, 87, 58, 169, 82, 115, 26, 59, 179 },
    232     { 63, 59, 90, 180, 59, 166, 93, 73, 154 },
    233     { 40, 40, 21, 116, 143, 209, 34, 39, 175 },
    234     { 47, 15, 16, 183, 34, 223, 49, 45, 183 },
    235     { 46, 17, 33, 183, 6, 98, 15, 32, 183 },
    236     { 57, 46, 22, 24, 128, 1, 54, 17, 37 },
    237     { 65, 32, 73, 115, 28, 128, 23, 128, 205 },
    238     { 40, 3, 9, 115, 51, 192, 18, 6, 223 },
    239     { 87, 37, 9, 115, 59, 77, 64, 21, 47 } },
    240   { { 104, 55, 44, 218, 9, 54, 53, 130, 226 },
    241     { 64, 90, 70, 205, 40, 41, 23, 26, 57 },
    242     { 54, 57, 112, 184, 5, 41, 38, 166, 213 },
    243     { 30, 34, 26, 133, 152, 116, 10, 32, 134 },
    244     { 39, 19, 53, 221, 26, 114, 32, 73, 255 },
    245     { 31, 9, 65, 234, 2, 15, 1, 118, 73 },
    246     { 75, 32, 12, 51, 192, 255, 160, 43, 51 },
    247     { 88, 31, 35, 67, 102, 85, 55, 186, 85 },
    248     { 56, 21, 23, 111, 59, 205, 45, 37, 192 },
    249     { 55, 38, 70, 124, 73, 102, 1, 34, 98 } },
    250   { { 125, 98, 42, 88, 104, 85, 117, 175, 82 },
    251     { 95, 84, 53, 89, 128, 100, 113, 101, 45 },
    252     { 75, 79, 123, 47, 51, 128, 81, 171, 1 },
    253     { 57, 17, 5, 71, 102, 57, 53, 41, 49 },
    254     { 38, 33, 13, 121, 57, 73, 26, 1, 85 },
    255     { 41, 10, 67, 138, 77, 110, 90, 47, 114 },
    256     { 115, 21, 2, 10, 102, 255, 166, 23, 6 },
    257     { 101, 29, 16, 10, 85, 128, 101, 196, 26 },
    258     { 57, 18, 10, 102, 102, 213, 34, 20, 43 },
    259     { 117, 20, 15, 36, 163, 128, 68, 1, 26 } },
    260   { { 102, 61, 71, 37, 34, 53, 31, 243, 192 },
    261     { 69, 60, 71, 38, 73, 119, 28, 222, 37 },
    262     { 68, 45, 128, 34, 1, 47, 11, 245, 171 },
    263     { 62, 17, 19, 70, 146, 85, 55, 62, 70 },
    264     { 37, 43, 37, 154, 100, 163, 85, 160, 1 },
    265     { 63, 9, 92, 136, 28, 64, 32, 201, 85 },
    266     { 75, 15, 9, 9, 64, 255, 184, 119, 16 },
    267     { 86, 6, 28, 5, 64, 255, 25, 248, 1 },
    268     { 56, 8, 17, 132, 137, 255, 55, 116, 128 },
    269     { 58, 15, 20, 82, 135, 57, 26, 121, 40 } },
    270   { { 164, 50, 31, 137, 154, 133, 25, 35, 218 },
    271     { 51, 103, 44, 131, 131, 123, 31, 6, 158 },
    272     { 86, 40, 64, 135, 148, 224, 45, 183, 128 },
    273     { 22, 26, 17, 131, 240, 154, 14, 1, 209 },
    274     { 45, 16, 21, 91, 64, 222, 7, 1, 197 },
    275     { 56, 21, 39, 155, 60, 138, 23, 102, 213 },
    276     { 83, 12, 13, 54, 192, 255, 68, 47, 28 },
    277     { 85, 26, 85, 85, 128, 128, 32, 146, 171 },
    278     { 18, 11, 7, 63, 144, 171, 4, 4, 246 },
    279     { 35, 27, 10, 146, 174, 171, 12, 26, 128 } },
    280   { { 190, 80, 35, 99, 180, 80, 126, 54, 45 },
    281     { 85, 126, 47, 87, 176, 51, 41, 20, 32 },
    282     { 101, 75, 128, 139, 118, 146, 116, 128, 85 },
    283     { 56, 41, 15, 176, 236, 85, 37, 9, 62 },
    284     { 71, 30, 17, 119, 118, 255, 17, 18, 138 },
    285     { 101, 38, 60, 138, 55, 70, 43, 26, 142 },
    286     { 146, 36, 19, 30, 171, 255, 97, 27, 20 },
    287     { 138, 45, 61, 62, 219, 1, 81, 188, 64 },
    288     { 32, 41, 20, 117, 151, 142, 20, 21, 163 },
    289     { 112, 19, 12, 61, 195, 128, 48, 4, 24 } }
    290 };
    291 
    292 void VP8ResetProba(VP8Proba* const proba) {
    293   memset(proba->segments, 255u, sizeof(proba->segments));
    294   // proba->bands[][] is initialized later
    295 }
    296 
    297 static void ParseIntraMode(VP8BitReader* const br,
    298                            VP8Decoder* const dec, int mb_x) {
    299   uint8_t* const top = dec->intra_t + 4 * mb_x;
    300   uint8_t* const left = dec->intra_l;
    301   VP8MBData* const block = dec->mb_data + mb_x;
    302 
    303   // Note: we don't save segment map (yet), as we don't expect
    304   // to decode more than 1 keyframe.
    305   if (dec->segment_hdr.update_map) {
    306     // Hardcoded tree parsing
    307     block->segment = !VP8GetBit(br, dec->proba.segments[0], "segments")
    308                    ?  VP8GetBit(br, dec->proba.segments[1], "segments")
    309                    :  VP8GetBit(br, dec->proba.segments[2], "segments") + 2;
    310   } else {
    311     block->segment = 0;  // default for intra
    312   }
    313   if (dec->use_skip_proba) block->skip = VP8GetBit(br, dec->skip_p, "skip");
    314 
    315   block->is_i4x4 = !VP8GetBit(br, 145, "block-size");
    316   if (!block->is_i4x4) {
    317     // Hardcoded 16x16 intra-mode decision tree.
    318     const int ymode =
    319         VP8GetBit(br, 156, "pred-modes") ?
    320             (VP8GetBit(br, 128, "pred-modes") ? TM_PRED : H_PRED) :
    321             (VP8GetBit(br, 163, "pred-modes") ? V_PRED : DC_PRED);
    322     block->imodes[0] = ymode;
    323     memset(top, ymode, 4 * sizeof(*top));
    324     memset(left, ymode, 4 * sizeof(*left));
    325   } else {
    326     uint8_t* modes = block->imodes;
    327     int y;
    328     for (y = 0; y < 4; ++y) {
    329       int ymode = left[y];
    330       int x;
    331       for (x = 0; x < 4; ++x) {
    332         const uint8_t* const prob = kBModesProba[top[x]][ymode];
    333 #if (USE_GENERIC_TREE == 1)
    334         // Generic tree-parsing
    335         int i = kYModesIntra4[VP8GetBit(br, prob[0], "pred-modes")];
    336         while (i > 0) {
    337           i = kYModesIntra4[2 * i + VP8GetBit(br, prob[i], "pred-modes")];
    338         }
    339         ymode = -i;
    340 #else
    341         // Hardcoded tree parsing
    342         ymode = !VP8GetBit(br, prob[0], "pred-modes") ? B_DC_PRED :
    343                   !VP8GetBit(br, prob[1], "pred-modes") ? B_TM_PRED :
    344                     !VP8GetBit(br, prob[2], "pred-modes") ? B_VE_PRED :
    345                       !VP8GetBit(br, prob[3], "pred-modes") ?
    346                         (!VP8GetBit(br, prob[4], "pred-modes") ? B_HE_PRED :
    347                           (!VP8GetBit(br, prob[5], "pred-modes") ? B_RD_PRED
    348                                                                  : B_VR_PRED)) :
    349                         (!VP8GetBit(br, prob[6], "pred-modes") ? B_LD_PRED :
    350                           (!VP8GetBit(br, prob[7], "pred-modes") ? B_VL_PRED :
    351                             (!VP8GetBit(br, prob[8], "pred-modes") ? B_HD_PRED
    352                                                                    : B_HU_PRED))
    353                         );
    354 #endif  // USE_GENERIC_TREE
    355         top[x] = ymode;
    356       }
    357       memcpy(modes, top, 4 * sizeof(*top));
    358       modes += 4;
    359       left[y] = ymode;
    360     }
    361   }
    362   // Hardcoded UVMode decision tree
    363   block->uvmode = !VP8GetBit(br, 142, "pred-modes-uv") ? DC_PRED
    364                 : !VP8GetBit(br, 114, "pred-modes-uv") ? V_PRED
    365                 : VP8GetBit(br, 183, "pred-modes-uv") ? TM_PRED : H_PRED;
    366 }
    367 
    368 int VP8ParseIntraModeRow(VP8BitReader* const br, VP8Decoder* const dec) {
    369   int mb_x;
    370   for (mb_x = 0; mb_x < dec->mb_w; ++mb_x) {
    371     ParseIntraMode(br, dec, mb_x);
    372   }
    373   return !dec->br.eof;
    374 }
    375 
    376 //------------------------------------------------------------------------------
    377 // Paragraph 13
    378 
    379 static const uint8_t
    380     CoeffsUpdateProba[NUM_TYPES][NUM_BANDS][NUM_CTX][NUM_PROBAS] = {
    381   { { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    382       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    383       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    384     },
    385     { { 176, 246, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    386       { 223, 241, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
    387       { 249, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 }
    388     },
    389     { { 255, 244, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
    390       { 234, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    391       { 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    392     },
    393     { { 255, 246, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    394       { 239, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    395       { 254, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
    396     },
    397     { { 255, 248, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    398       { 251, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    399       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    400     },
    401     { { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    402       { 251, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    403       { 254, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
    404     },
    405     { { 255, 254, 253, 255, 254, 255, 255, 255, 255, 255, 255 },
    406       { 250, 255, 254, 255, 254, 255, 255, 255, 255, 255, 255 },
    407       { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    408     },
    409     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    410       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    411       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    412     }
    413   },
    414   { { { 217, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    415       { 225, 252, 241, 253, 255, 255, 254, 255, 255, 255, 255 },
    416       { 234, 250, 241, 250, 253, 255, 253, 254, 255, 255, 255 }
    417     },
    418     { { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    419       { 223, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    420       { 238, 253, 254, 254, 255, 255, 255, 255, 255, 255, 255 }
    421     },
    422     { { 255, 248, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    423       { 249, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    424       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    425     },
    426     { { 255, 253, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    427       { 247, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    428       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    429     },
    430     { { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    431       { 252, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    432       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    433     },
    434     { { 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    435       { 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    436       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    437     },
    438     { { 255, 254, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
    439       { 250, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    440       { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    441     },
    442     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    443       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    444       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    445     }
    446   },
    447   { { { 186, 251, 250, 255, 255, 255, 255, 255, 255, 255, 255 },
    448       { 234, 251, 244, 254, 255, 255, 255, 255, 255, 255, 255 },
    449       { 251, 251, 243, 253, 254, 255, 254, 255, 255, 255, 255 }
    450     },
    451     { { 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    452       { 236, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    453       { 251, 253, 253, 254, 254, 255, 255, 255, 255, 255, 255 }
    454     },
    455     { { 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    456       { 254, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    457       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    458     },
    459     { { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    460       { 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    461       { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    462     },
    463     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    464       { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    465       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    466     },
    467     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    468       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    469       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    470     },
    471     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    472       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    473       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    474     },
    475     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    476       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    477       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    478     }
    479   },
    480   { { { 248, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    481       { 250, 254, 252, 254, 255, 255, 255, 255, 255, 255, 255 },
    482       { 248, 254, 249, 253, 255, 255, 255, 255, 255, 255, 255 }
    483     },
    484     { { 255, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
    485       { 246, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
    486       { 252, 254, 251, 254, 254, 255, 255, 255, 255, 255, 255 }
    487     },
    488     { { 255, 254, 252, 255, 255, 255, 255, 255, 255, 255, 255 },
    489       { 248, 254, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
    490       { 253, 255, 254, 254, 255, 255, 255, 255, 255, 255, 255 }
    491     },
    492     { { 255, 251, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    493       { 245, 251, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    494       { 253, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
    495     },
    496     { { 255, 251, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
    497       { 252, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    498       { 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    499     },
    500     { { 255, 252, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    501       { 249, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 },
    502       { 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255 }
    503     },
    504     { { 255, 255, 253, 255, 255, 255, 255, 255, 255, 255, 255 },
    505       { 250, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    506       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    507     },
    508     { { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    509       { 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 },
    510       { 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255 }
    511     }
    512   }
    513 };
    514 
    515 // Paragraph 9.9
    516 
    517 static const uint8_t kBands[16 + 1] = {
    518   0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
    519   0  // extra entry as sentinel
    520 };
    521 
    522 void VP8ParseProba(VP8BitReader* const br, VP8Decoder* const dec) {
    523   VP8Proba* const proba = &dec->proba;
    524   int t, b, c, p;
    525   for (t = 0; t < NUM_TYPES; ++t) {
    526     for (b = 0; b < NUM_BANDS; ++b) {
    527       for (c = 0; c < NUM_CTX; ++c) {
    528         for (p = 0; p < NUM_PROBAS; ++p) {
    529           const int v =
    530               VP8GetBit(br, CoeffsUpdateProba[t][b][c][p], "global-header") ?
    531                         VP8GetValue(br, 8, "global-header") :
    532                         CoeffsProba0[t][b][c][p];
    533           proba->bands[t][b].probas[c][p] = v;
    534         }
    535       }
    536     }
    537     for (b = 0; b < 16 + 1; ++b) {
    538       proba->bands_ptr[t][b] = &proba->bands[t][kBands[b]];
    539     }
    540   }
    541   dec->use_skip_proba = VP8Get(br, "global-header");
    542   if (dec->use_skip_proba) {
    543     dec->skip_p = VP8GetValue(br, 8, "global-header");
    544   }
    545 }