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4349 | Serge | 1 | /* |
2 | * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder |
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3 | * Copyright (c) 2003 Michael Niedermayer |
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4 | * |
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5 | * This file is part of FFmpeg. |
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6 | * |
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7 | * FFmpeg is free software; you can redistribute it and/or |
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8 | * modify it under the terms of the GNU Lesser General Public |
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9 | * License as published by the Free Software Foundation; either |
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10 | * version 2.1 of the License, or (at your option) any later version. |
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11 | * |
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12 | * FFmpeg is distributed in the hope that it will be useful, |
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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15 | * Lesser General Public License for more details. |
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16 | * |
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17 | * You should have received a copy of the GNU Lesser General Public |
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18 | * License along with FFmpeg; if not, write to the Free Software |
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19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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20 | */ |
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21 | |||
22 | /** |
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23 | * @file |
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24 | * Context Adaptive Binary Arithmetic Coder inline functions |
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25 | */ |
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26 | |||
27 | #ifndef AVCODEC_CABAC_FUNCTIONS_H |
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28 | #define AVCODEC_CABAC_FUNCTIONS_H |
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29 | |||
30 | #include |
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31 | |||
32 | #include "cabac.h" |
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33 | #include "config.h" |
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34 | |||
35 | #if ARCH_X86 |
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36 | # include "x86/cabac.h" |
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37 | #endif |
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38 | |||
39 | extern uint8_t ff_h264_cabac_tables[512 + 4*2*64 + 4*64 + 63]; |
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40 | static uint8_t * const ff_h264_norm_shift = ff_h264_cabac_tables + H264_NORM_SHIFT_OFFSET; |
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41 | static uint8_t * const ff_h264_lps_range = ff_h264_cabac_tables + H264_LPS_RANGE_OFFSET; |
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42 | static uint8_t * const ff_h264_mlps_state = ff_h264_cabac_tables + H264_MLPS_STATE_OFFSET; |
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43 | static uint8_t * const ff_h264_last_coeff_flag_offset_8x8 = ff_h264_cabac_tables + H264_LAST_COEFF_FLAG_OFFSET_8x8_OFFSET; |
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44 | |||
45 | static void refill(CABACContext *c){ |
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46 | #if CABAC_BITS == 16 |
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47 | c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1); |
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48 | #else |
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49 | c->low+= c->bytestream[0]<<1; |
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50 | #endif |
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51 | c->low -= CABAC_MASK; |
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52 | #if !UNCHECKED_BITSTREAM_READER |
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53 | if (c->bytestream < c->bytestream_end) |
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54 | #endif |
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55 | c->bytestream += CABAC_BITS / 8; |
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56 | } |
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57 | |||
58 | static inline void renorm_cabac_decoder_once(CABACContext *c){ |
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59 | int shift= (uint32_t)(c->range - 0x100)>>31; |
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60 | c->range<<= shift; |
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61 | c->low <<= shift; |
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62 | if(!(c->low & CABAC_MASK)) |
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63 | refill(c); |
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64 | } |
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65 | |||
66 | #ifndef get_cabac_inline |
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67 | static void refill2(CABACContext *c){ |
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68 | int i, x; |
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69 | |||
70 | x= c->low ^ (c->low-1); |
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71 | i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)]; |
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72 | |||
73 | x= -CABAC_MASK; |
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74 | |||
75 | #if CABAC_BITS == 16 |
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76 | x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1); |
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77 | #else |
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78 | x+= c->bytestream[0]<<1; |
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79 | #endif |
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80 | |||
81 | c->low += x< |
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82 | #if !UNCHECKED_BITSTREAM_READER |
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83 | if (c->bytestream < c->bytestream_end) |
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84 | #endif |
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85 | c->bytestream += CABAC_BITS/8; |
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86 | } |
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87 | |||
88 | static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){ |
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89 | int s = *state; |
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90 | int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + s]; |
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91 | int bit, lps_mask; |
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92 | |||
93 | c->range -= RangeLPS; |
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94 | lps_mask= ((c->range<<(CABAC_BITS+1)) - c->low)>>31; |
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95 | |||
96 | c->low -= (c->range<<(CABAC_BITS+1)) & lps_mask; |
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97 | c->range += (RangeLPS - c->range) & lps_mask; |
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98 | |||
99 | s^=lps_mask; |
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100 | *state= (ff_h264_mlps_state+128)[s]; |
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101 | bit= s&1; |
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102 | |||
103 | lps_mask= ff_h264_norm_shift[c->range]; |
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104 | c->range<<= lps_mask; |
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105 | c->low <<= lps_mask; |
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106 | if(!(c->low & CABAC_MASK)) |
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107 | refill2(c); |
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108 | return bit; |
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109 | } |
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110 | #endif |
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111 | |||
112 | static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){ |
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113 | return get_cabac_inline(c,state); |
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114 | } |
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115 | |||
116 | static int av_unused get_cabac(CABACContext *c, uint8_t * const state){ |
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117 | return get_cabac_inline(c,state); |
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118 | } |
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119 | |||
120 | #ifndef get_cabac_bypass |
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121 | static int av_unused get_cabac_bypass(CABACContext *c){ |
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122 | int range; |
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123 | c->low += c->low; |
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124 | |||
125 | if(!(c->low & CABAC_MASK)) |
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126 | refill(c); |
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127 | |||
128 | range= c->range<<(CABAC_BITS+1); |
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129 | if(c->low < range){ |
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130 | return 0; |
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131 | }else{ |
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132 | c->low -= range; |
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133 | return 1; |
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134 | } |
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135 | } |
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136 | #endif |
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137 | |||
138 | #ifndef get_cabac_bypass_sign |
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139 | static av_always_inline int get_cabac_bypass_sign(CABACContext *c, int val){ |
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140 | int range, mask; |
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141 | c->low += c->low; |
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142 | |||
143 | if(!(c->low & CABAC_MASK)) |
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144 | refill(c); |
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145 | |||
146 | range= c->range<<(CABAC_BITS+1); |
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147 | c->low -= range; |
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148 | mask= c->low >> 31; |
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149 | range &= mask; |
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150 | c->low += range; |
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151 | return (val^mask)-mask; |
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152 | } |
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153 | #endif |
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154 | |||
155 | /** |
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156 | * |
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157 | * @return the number of bytes read or 0 if no end |
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158 | */ |
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159 | static int av_unused get_cabac_terminate(CABACContext *c){ |
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160 | c->range -= 2; |
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161 | if(c->low < c->range<<(CABAC_BITS+1)){ |
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162 | renorm_cabac_decoder_once(c); |
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163 | return 0; |
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164 | }else{ |
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165 | return c->bytestream - c->bytestream_start; |
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166 | } |
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167 | } |
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168 | |||
169 | /** |
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170 | * Skip @p n bytes and reset the decoder. |
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171 | * @return the address of the first skipped byte or NULL if there's less than @p n bytes left |
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172 | */ |
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173 | static av_unused const uint8_t* skip_bytes(CABACContext *c, int n) { |
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174 | const uint8_t *ptr = c->bytestream; |
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175 | |||
176 | if (c->low & 0x1) |
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177 | ptr--; |
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178 | #if CABAC_BITS == 16 |
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179 | if (c->low & 0x1FF) |
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180 | ptr--; |
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181 | #endif |
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182 | if ((int) (c->bytestream_end - ptr) < n) |
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183 | return NULL; |
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184 | ff_init_cabac_decoder(c, ptr + n, c->bytestream_end - ptr - n); |
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185 | |||
186 | return ptr; |
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187 | } |
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188 | |||
189 | #endif /* AVCODEC_CABAC_FUNCTIONS_H */>(CABAC_BITS+1)){ |