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) 2010-2014, 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/Debug.h" |
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40 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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41 | #include "TLibCommon/TComCodingStatistics.h" |
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42 | #endif |
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43 | |
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44 | //! \ingroup TLibDecoder |
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45 | //! \{ |
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46 | |
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47 | TDecBinCABAC::TDecBinCABAC() |
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48 | : m_pcTComBitstream( 0 ) |
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49 | { |
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50 | } |
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51 | |
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52 | TDecBinCABAC::~TDecBinCABAC() |
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53 | { |
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54 | } |
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55 | |
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56 | Void |
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57 | TDecBinCABAC::init( TComInputBitstream* pcTComBitstream ) |
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58 | { |
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59 | m_pcTComBitstream = pcTComBitstream; |
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60 | } |
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61 | |
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62 | Void |
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63 | TDecBinCABAC::uninit() |
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64 | { |
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65 | m_pcTComBitstream = 0; |
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66 | } |
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67 | |
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68 | Void |
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69 | TDecBinCABAC::start() |
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70 | { |
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71 | assert( m_pcTComBitstream->getNumBitsUntilByteAligned() == 0 ); |
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72 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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73 | TComCodingStatistics::UpdateCABACStat(STATS__CABAC_INITIALISATION, 512, 510, 0); |
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74 | #endif |
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75 | m_uiRange = 510; |
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76 | m_bitsNeeded = -8; |
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77 | m_uiValue = (m_pcTComBitstream->readByte() << 8); |
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78 | m_uiValue |= m_pcTComBitstream->readByte(); |
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79 | } |
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80 | |
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81 | Void |
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82 | TDecBinCABAC::finish() |
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83 | { |
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84 | UInt lastByte; |
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85 | |
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86 | m_pcTComBitstream->peekPreviousByte( lastByte ); |
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87 | // Check for proper stop/alignment pattern |
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88 | assert( ((lastByte << (8 + m_bitsNeeded)) & 0xff) == 0x80 ); |
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89 | } |
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90 | |
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91 | /** |
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92 | - Copy CABAC state. |
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93 | . |
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94 | \param pcTDecBinIf The source CABAC engine. |
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95 | */ |
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96 | Void |
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97 | TDecBinCABAC::copyState( const TDecBinIf* pcTDecBinIf ) |
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98 | { |
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99 | const TDecBinCABAC* pcTDecBinCABAC = pcTDecBinIf->getTDecBinCABAC(); |
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100 | m_uiRange = pcTDecBinCABAC->m_uiRange; |
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101 | m_uiValue = pcTDecBinCABAC->m_uiValue; |
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102 | m_bitsNeeded= pcTDecBinCABAC->m_bitsNeeded; |
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103 | } |
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104 | |
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105 | |
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106 | |
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107 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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108 | Void TDecBinCABAC::decodeBin( UInt& ruiBin, ContextModel &rcCtxModel, const TComCodingStatisticsClassType &whichStat ) |
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109 | #else |
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110 | Void TDecBinCABAC::decodeBin( UInt& ruiBin, ContextModel &rcCtxModel ) |
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111 | #endif |
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112 | { |
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113 | #ifdef DEBUG_CABAC_BINS |
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114 | const UInt startingRange = m_uiRange; |
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115 | #endif |
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116 | |
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117 | UInt uiLPS = TComCABACTables::sm_aucLPSTable[ rcCtxModel.getState() ][ ( m_uiRange >> 6 ) - 4 ]; |
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118 | m_uiRange -= uiLPS; |
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119 | UInt scaledRange = m_uiRange << 7; |
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120 | |
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121 | if( m_uiValue < scaledRange ) |
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122 | { |
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123 | // MPS path |
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124 | ruiBin = rcCtxModel.getMps(); |
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125 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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126 | TComCodingStatistics::UpdateCABACStat(whichStat, m_uiRange+uiLPS, m_uiRange, Int(ruiBin)); |
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127 | #endif |
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128 | rcCtxModel.updateMPS(); |
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129 | |
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130 | if ( scaledRange < ( 256 << 7 ) ) |
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131 | { |
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132 | m_uiRange = scaledRange >> 6; |
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133 | m_uiValue += m_uiValue; |
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134 | |
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135 | if ( ++m_bitsNeeded == 0 ) |
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136 | { |
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137 | m_bitsNeeded = -8; |
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138 | m_uiValue += m_pcTComBitstream->readByte(); |
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139 | } |
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140 | } |
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141 | } |
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142 | else |
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143 | { |
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144 | // LPS path |
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145 | ruiBin = 1 - rcCtxModel.getMps(); |
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146 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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147 | TComCodingStatistics::UpdateCABACStat(whichStat, m_uiRange+uiLPS, uiLPS, Int(ruiBin)); |
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148 | #endif |
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149 | Int numBits = TComCABACTables::sm_aucRenormTable[ uiLPS >> 3 ]; |
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150 | m_uiValue = ( m_uiValue - scaledRange ) << numBits; |
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151 | m_uiRange = uiLPS << numBits; |
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152 | rcCtxModel.updateLPS(); |
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153 | |
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154 | m_bitsNeeded += numBits; |
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155 | |
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156 | if ( m_bitsNeeded >= 0 ) |
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157 | { |
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158 | m_uiValue += m_pcTComBitstream->readByte() << m_bitsNeeded; |
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159 | m_bitsNeeded -= 8; |
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160 | } |
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161 | } |
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162 | |
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163 | #ifdef DEBUG_CABAC_BINS |
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164 | if ((g_debugCounter + debugCabacBinWindow) >= debugCabacBinTargetLine) |
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165 | { |
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166 | std::cout << g_debugCounter << ": coding bin value " << ruiBin << ", range = [" << startingRange << "->" << m_uiRange << "]\n"; |
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167 | } |
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168 | |
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169 | if (g_debugCounter >= debugCabacBinTargetLine) |
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170 | { |
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171 | Char breakPointThis; |
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172 | breakPointThis = 7; |
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173 | } |
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174 | if (g_debugCounter >= (debugCabacBinTargetLine + debugCabacBinWindow)) |
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175 | { |
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176 | exit(0); |
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177 | } |
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178 | g_debugCounter++; |
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179 | #endif |
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180 | } |
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181 | |
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182 | |
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183 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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184 | Void TDecBinCABAC::decodeBinEP( UInt& ruiBin, const TComCodingStatisticsClassType &whichStat ) |
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185 | #else |
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186 | Void TDecBinCABAC::decodeBinEP( UInt& ruiBin ) |
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187 | #endif |
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188 | { |
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189 | if (m_uiRange == 256) |
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190 | { |
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191 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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192 | decodeAlignedBinsEP(ruiBin, 1, whichStat); |
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193 | #else |
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194 | decodeAlignedBinsEP(ruiBin, 1); |
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195 | #endif |
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196 | return; |
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197 | } |
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198 | |
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199 | m_uiValue += m_uiValue; |
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200 | |
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201 | if ( ++m_bitsNeeded >= 0 ) |
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202 | { |
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203 | m_bitsNeeded = -8; |
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204 | m_uiValue += m_pcTComBitstream->readByte(); |
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205 | } |
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206 | |
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207 | ruiBin = 0; |
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208 | UInt scaledRange = m_uiRange << 7; |
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209 | if ( m_uiValue >= scaledRange ) |
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210 | { |
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211 | ruiBin = 1; |
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212 | m_uiValue -= scaledRange; |
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213 | } |
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214 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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215 | TComCodingStatistics::IncrementStatisticEP(whichStat, 1, Int(ruiBin)); |
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216 | #endif |
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217 | } |
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218 | |
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219 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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220 | Void TDecBinCABAC::decodeBinsEP( UInt& ruiBin, Int numBins, const TComCodingStatisticsClassType &whichStat ) |
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221 | #else |
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222 | Void TDecBinCABAC::decodeBinsEP( UInt& ruiBin, Int numBins ) |
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223 | #endif |
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224 | { |
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225 | if (m_uiRange == 256) |
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226 | { |
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227 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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228 | decodeAlignedBinsEP(ruiBin, numBins, whichStat); |
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229 | #else |
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230 | decodeAlignedBinsEP(ruiBin, numBins); |
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231 | #endif |
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232 | return; |
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233 | } |
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234 | |
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235 | UInt bins = 0; |
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236 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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237 | Int origNumBins=numBins; |
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238 | #endif |
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239 | while ( numBins > 8 ) |
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240 | { |
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241 | m_uiValue = ( m_uiValue << 8 ) + ( m_pcTComBitstream->readByte() << ( 8 + m_bitsNeeded ) ); |
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242 | |
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243 | UInt scaledRange = m_uiRange << 15; |
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244 | for ( Int i = 0; i < 8; i++ ) |
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245 | { |
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246 | bins += bins; |
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247 | scaledRange >>= 1; |
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248 | if ( m_uiValue >= scaledRange ) |
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249 | { |
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250 | bins++; |
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251 | m_uiValue -= scaledRange; |
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252 | } |
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253 | } |
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254 | numBins -= 8; |
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255 | } |
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256 | |
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257 | m_bitsNeeded += numBins; |
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258 | m_uiValue <<= numBins; |
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259 | |
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260 | if ( m_bitsNeeded >= 0 ) |
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261 | { |
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262 | m_uiValue += m_pcTComBitstream->readByte() << m_bitsNeeded; |
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263 | m_bitsNeeded -= 8; |
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264 | } |
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265 | |
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266 | UInt scaledRange = m_uiRange << ( numBins + 7 ); |
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267 | for ( Int i = 0; i < numBins; i++ ) |
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268 | { |
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269 | bins += bins; |
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270 | scaledRange >>= 1; |
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271 | if ( m_uiValue >= scaledRange ) |
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272 | { |
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273 | bins++; |
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274 | m_uiValue -= scaledRange; |
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275 | } |
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276 | } |
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277 | |
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278 | ruiBin = bins; |
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279 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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280 | TComCodingStatistics::IncrementStatisticEP(whichStat, origNumBins, Int(ruiBin)); |
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281 | #endif |
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282 | } |
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283 | |
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284 | Void TDecBinCABAC::align() |
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285 | { |
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286 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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287 | TComCodingStatistics::UpdateCABACStat(STATS__CABAC_EP_BIT_ALIGNMENT, m_uiRange, 256, 0); |
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288 | #endif |
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289 | m_uiRange = 256; |
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290 | } |
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291 | |
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292 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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293 | Void TDecBinCABAC::decodeAlignedBinsEP( UInt& ruiBins, Int numBins, const class TComCodingStatisticsClassType &whichStat ) |
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294 | #else |
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295 | Void TDecBinCABAC::decodeAlignedBinsEP( UInt& ruiBins, Int numBins ) |
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296 | #endif |
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297 | { |
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298 | Int binsRemaining = numBins; |
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299 | ruiBins = 0; |
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300 | |
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301 | assert(m_uiRange == 256); //aligned decode only works when range = 256 |
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302 | |
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303 | while (binsRemaining > 0) |
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304 | { |
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305 | const UInt binsToRead = std::min<UInt>(binsRemaining, 8); //read bytes if able to take advantage of the system's byte-read function |
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306 | const UInt binMask = (1 << binsToRead) - 1; |
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307 | |
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308 | //The MSB of m_uiValue is known to be 0 because range is 256. Therefore: |
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309 | // > The comparison against the symbol range of 128 is simply a test on the next-most-significant bit |
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310 | // > "Subtracting" the symbol range if the decoded bin is 1 simply involves clearing that bit. |
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311 | // |
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312 | //As a result, the required bins are simply the <binsToRead> next-most-significant bits of m_uiValue |
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313 | //(m_uiValue is stored MSB-aligned in a 16-bit buffer - hence the shift of 15) |
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314 | // |
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315 | // m_uiValue = |0|V|V|V|V|V|V|V|V|B|B|B|B|B|B|B| (V = usable bit, B = potential buffered bit (buffer refills when m_bitsNeeded >= 0)) |
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316 | // |
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317 | const UInt newBins = (m_uiValue >> (15 - binsToRead)) & binMask; |
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318 | |
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319 | ruiBins = (ruiBins << binsToRead) | newBins; |
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320 | m_uiValue = (m_uiValue << binsToRead) & 0x7FFF; |
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321 | |
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322 | binsRemaining -= binsToRead; |
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323 | m_bitsNeeded += binsToRead; |
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324 | |
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325 | if (m_bitsNeeded >= 0) |
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326 | { |
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327 | m_uiValue |= m_pcTComBitstream->readByte() << m_bitsNeeded; |
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328 | m_bitsNeeded -= 8; |
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329 | } |
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330 | } |
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331 | |
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332 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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333 | TComCodingStatistics::IncrementStatisticEP(whichStat, numBins, Int(ruiBins)); |
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334 | #endif |
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335 | } |
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336 | |
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337 | Void |
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338 | TDecBinCABAC::decodeBinTrm( UInt& ruiBin ) |
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339 | { |
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340 | m_uiRange -= 2; |
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341 | UInt scaledRange = m_uiRange << 7; |
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342 | if( m_uiValue >= scaledRange ) |
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343 | { |
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344 | ruiBin = 1; |
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345 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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346 | TComCodingStatistics::UpdateCABACStat(STATS__CABAC_TRM_BITS, m_uiRange+2, 2, ruiBin); |
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347 | TComCodingStatistics::IncrementStatisticEP(STATS__BYTE_ALIGNMENT_BITS, -m_bitsNeeded, 0); |
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348 | #endif |
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349 | } |
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350 | else |
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351 | { |
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352 | ruiBin = 0; |
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353 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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354 | TComCodingStatistics::UpdateCABACStat(STATS__CABAC_TRM_BITS, m_uiRange+2, m_uiRange, ruiBin); |
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355 | #endif |
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356 | if ( scaledRange < ( 256 << 7 ) ) |
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357 | { |
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358 | m_uiRange = scaledRange >> 6; |
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359 | m_uiValue += m_uiValue; |
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360 | |
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361 | if ( ++m_bitsNeeded == 0 ) |
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362 | { |
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363 | m_bitsNeeded = -8; |
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364 | m_uiValue += m_pcTComBitstream->readByte(); |
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365 | } |
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366 | } |
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367 | } |
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368 | } |
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369 | |
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370 | /** Read a PCM code. |
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371 | * \param uiLength code bit-depth |
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372 | * \param ruiCode pointer to PCM code value |
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373 | * \returns Void |
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374 | */ |
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375 | Void TDecBinCABAC::xReadPCMCode(UInt uiLength, UInt& ruiCode) |
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376 | { |
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377 | assert ( uiLength > 0 ); |
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378 | m_pcTComBitstream->read (uiLength, ruiCode); |
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379 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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380 | TComCodingStatistics::IncrementStatisticEP(STATS__CABAC_PCM_CODE_BITS, uiLength, ruiCode); |
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381 | #endif |
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382 | } |
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383 | //! \} |
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