1 | /* The copyright in this software is being made available under the BSD |
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2 | * License, included below. This software may be subject to other third party |
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3 | * and contributor rights, including patent rights, and no such rights are |
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4 | * granted under this license. |
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5 | * |
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6 | * Copyright (c) 2010-2015, ITU/ISO/IEC |
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7 | * All rights reserved. |
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8 | * |
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9 | * Redistribution and use in source and binary forms, with or without |
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10 | * modification, are permitted provided that the following conditions are met: |
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11 | * |
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12 | * * Redistributions of source code must retain the above copyright notice, |
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13 | * this list of conditions and the following disclaimer. |
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14 | * * Redistributions in binary form must reproduce the above copyright notice, |
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15 | * this list of conditions and the following disclaimer in the documentation |
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16 | * and/or other materials provided with the distribution. |
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17 | * * Neither the name of the ITU/ISO/IEC nor the names of its contributors may |
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18 | * be used to endorse or promote products derived from this software without |
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19 | * specific prior written permission. |
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20 | * |
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21 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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22 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS |
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25 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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26 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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27 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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28 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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29 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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30 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF |
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31 | * THE POSSIBILITY OF SUCH DAMAGE. |
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32 | */ |
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33 | |
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34 | /** \file TDecBinCoderCABAC.cpp |
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35 | \brief binary entropy decoder of CABAC |
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36 | */ |
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37 | |
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38 | #include "TDecBinCoderCABAC.h" |
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39 | #include "../TLibCommon/TComRom.h" |
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40 | |
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41 | //! \ingroup TLibDecoder |
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42 | //! \{ |
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43 | |
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44 | TDecBinCABAC::TDecBinCABAC() |
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45 | : m_pcTComBitstream( 0 ) |
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46 | { |
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47 | } |
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48 | |
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49 | TDecBinCABAC::~TDecBinCABAC() |
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50 | { |
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51 | } |
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52 | |
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53 | Void |
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54 | TDecBinCABAC::init( TComInputBitstream* pcTComBitstream ) |
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55 | { |
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56 | m_pcTComBitstream = pcTComBitstream; |
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57 | } |
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58 | |
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59 | Void |
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60 | TDecBinCABAC::uninit() |
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61 | { |
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62 | m_pcTComBitstream = 0; |
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63 | } |
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64 | |
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65 | Void |
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66 | TDecBinCABAC::start() |
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67 | { |
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68 | assert( m_pcTComBitstream->getNumBitsUntilByteAligned() == 0 ); |
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69 | m_uiRange = 510; |
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70 | m_bitsNeeded = -8; |
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71 | m_uiValue = (m_pcTComBitstream->readByte() << 8); |
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72 | m_uiValue |= m_pcTComBitstream->readByte(); |
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73 | } |
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74 | |
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75 | Void |
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76 | TDecBinCABAC::finish() |
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77 | { |
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78 | UInt lastByte; |
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79 | |
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80 | m_pcTComBitstream->peekPreviousByte( lastByte ); |
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81 | // Check for proper stop/alignment pattern |
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82 | assert( ((lastByte << (8 + m_bitsNeeded)) & 0xff) == 0x80 ); |
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83 | } |
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84 | |
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85 | /** |
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86 | - Copy CABAC state. |
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87 | . |
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88 | \param pcTDecBinIf The source CABAC engine. |
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89 | */ |
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90 | Void |
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91 | TDecBinCABAC::copyState( TDecBinIf* pcTDecBinIf ) |
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92 | { |
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93 | TDecBinCABAC* pcTDecBinCABAC = pcTDecBinIf->getTDecBinCABAC(); |
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94 | m_uiRange = pcTDecBinCABAC->m_uiRange; |
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95 | m_uiValue = pcTDecBinCABAC->m_uiValue; |
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96 | m_bitsNeeded= pcTDecBinCABAC->m_bitsNeeded; |
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97 | } |
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98 | |
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99 | |
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100 | Void |
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101 | TDecBinCABAC::decodeBin( UInt& ruiBin, ContextModel &rcCtxModel ) |
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102 | { |
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103 | UInt uiLPS = TComCABACTables::sm_aucLPSTable[ rcCtxModel.getState() ][ ( m_uiRange >> 6 ) - 4 ]; |
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104 | m_uiRange -= uiLPS; |
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105 | UInt scaledRange = m_uiRange << 7; |
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106 | |
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107 | if( m_uiValue < scaledRange ) |
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108 | { |
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109 | // MPS path |
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110 | ruiBin = rcCtxModel.getMps(); |
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111 | rcCtxModel.updateMPS(); |
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112 | |
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113 | if ( scaledRange >= ( 256 << 7 ) ) |
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114 | { |
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115 | return; |
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116 | } |
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117 | |
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118 | m_uiRange = scaledRange >> 6; |
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119 | m_uiValue += m_uiValue; |
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120 | |
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121 | if ( ++m_bitsNeeded == 0 ) |
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122 | { |
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123 | m_bitsNeeded = -8; |
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124 | m_uiValue += m_pcTComBitstream->readByte(); |
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125 | } |
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126 | } |
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127 | else |
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128 | { |
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129 | // LPS path |
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130 | Int numBits = TComCABACTables::sm_aucRenormTable[ uiLPS >> 3 ]; |
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131 | m_uiValue = ( m_uiValue - scaledRange ) << numBits; |
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132 | m_uiRange = uiLPS << numBits; |
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133 | ruiBin = 1 - rcCtxModel.getMps(); |
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134 | rcCtxModel.updateLPS(); |
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135 | |
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136 | m_bitsNeeded += numBits; |
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137 | |
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138 | if ( m_bitsNeeded >= 0 ) |
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139 | { |
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140 | m_uiValue += m_pcTComBitstream->readByte() << m_bitsNeeded; |
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141 | m_bitsNeeded -= 8; |
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142 | } |
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143 | } |
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144 | } |
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145 | |
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146 | Void |
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147 | TDecBinCABAC::decodeBinEP( UInt& ruiBin ) |
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148 | { |
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149 | m_uiValue += m_uiValue; |
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150 | |
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151 | if ( ++m_bitsNeeded >= 0 ) |
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152 | { |
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153 | m_bitsNeeded = -8; |
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154 | m_uiValue += m_pcTComBitstream->readByte(); |
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155 | } |
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156 | |
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157 | ruiBin = 0; |
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158 | UInt scaledRange = m_uiRange << 7; |
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159 | if ( m_uiValue >= scaledRange ) |
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160 | { |
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161 | ruiBin = 1; |
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162 | m_uiValue -= scaledRange; |
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163 | } |
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164 | } |
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165 | |
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166 | Void TDecBinCABAC::decodeBinsEP( UInt& ruiBin, Int numBins ) |
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167 | { |
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168 | UInt bins = 0; |
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169 | |
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170 | while ( numBins > 8 ) |
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171 | { |
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172 | m_uiValue = ( m_uiValue << 8 ) + ( m_pcTComBitstream->readByte() << ( 8 + m_bitsNeeded ) ); |
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173 | |
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174 | UInt scaledRange = m_uiRange << 15; |
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175 | for ( Int i = 0; i < 8; i++ ) |
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176 | { |
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177 | bins += bins; |
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178 | scaledRange >>= 1; |
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179 | if ( m_uiValue >= scaledRange ) |
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180 | { |
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181 | bins++; |
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182 | m_uiValue -= scaledRange; |
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183 | } |
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184 | } |
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185 | numBins -= 8; |
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186 | } |
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187 | |
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188 | m_bitsNeeded += numBins; |
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189 | m_uiValue <<= numBins; |
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190 | |
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191 | if ( m_bitsNeeded >= 0 ) |
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192 | { |
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193 | m_uiValue += m_pcTComBitstream->readByte() << m_bitsNeeded; |
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194 | m_bitsNeeded -= 8; |
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195 | } |
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196 | |
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197 | UInt scaledRange = m_uiRange << ( numBins + 7 ); |
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198 | for ( Int i = 0; i < numBins; i++ ) |
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199 | { |
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200 | bins += bins; |
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201 | scaledRange >>= 1; |
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202 | if ( m_uiValue >= scaledRange ) |
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203 | { |
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204 | bins++; |
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205 | m_uiValue -= scaledRange; |
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206 | } |
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207 | } |
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208 | |
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209 | ruiBin = bins; |
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210 | } |
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211 | |
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212 | Void |
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213 | TDecBinCABAC::decodeBinTrm( UInt& ruiBin ) |
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214 | { |
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215 | m_uiRange -= 2; |
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216 | UInt scaledRange = m_uiRange << 7; |
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217 | if( m_uiValue >= scaledRange ) |
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218 | { |
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219 | ruiBin = 1; |
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220 | } |
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221 | else |
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222 | { |
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223 | ruiBin = 0; |
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224 | if ( scaledRange < ( 256 << 7 ) ) |
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225 | { |
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226 | m_uiRange = scaledRange >> 6; |
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227 | m_uiValue += m_uiValue; |
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228 | |
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229 | if ( ++m_bitsNeeded == 0 ) |
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230 | { |
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231 | m_bitsNeeded = -8; |
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232 | m_uiValue += m_pcTComBitstream->readByte(); |
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233 | } |
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234 | } |
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235 | } |
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236 | } |
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237 | |
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238 | /** Read a PCM code. |
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239 | * \param uiLength code bit-depth |
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240 | * \param ruiCode pointer to PCM code value |
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241 | * \returns Void |
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242 | */ |
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243 | Void TDecBinCABAC::xReadPCMCode(UInt uiLength, UInt& ruiCode) |
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244 | { |
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245 | assert ( uiLength > 0 ); |
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246 | m_pcTComBitstream->read (uiLength, ruiCode); |
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247 | } |
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248 | //! \} |
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