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 | /** |
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35 | \file AnnexBread.h |
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36 | \brief reading functions for Annex B byte streams |
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37 | */ |
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38 | |
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39 | #pragma once |
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40 | |
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41 | #ifndef __ANNEXBREAD__ |
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42 | #define __ANNEXBREAD__ |
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43 | |
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44 | #include <stdint.h> |
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45 | #include <istream> |
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46 | #include <vector> |
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47 | |
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48 | #include "TLibCommon/TypeDef.h" |
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49 | |
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50 | //! \ingroup TLibDecoder |
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51 | //! \{ |
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52 | |
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53 | class InputByteStream |
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54 | { |
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55 | public: |
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56 | /** |
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57 | * Create a bytestream reader that will extract bytes from |
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58 | * istream. |
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59 | * |
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60 | * NB, it isn't safe to access istream while in use by a |
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61 | * InputByteStream. |
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62 | * |
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63 | * Side-effects: the exception mask of istream is set to eofbit |
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64 | */ |
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65 | InputByteStream(std::istream& istream) |
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66 | : m_NumFutureBytes(0) |
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67 | , m_FutureBytes(0) |
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68 | , m_Input(istream) |
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69 | { |
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70 | istream.exceptions(std::istream::eofbit | std::istream::badbit); |
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71 | } |
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72 | |
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73 | /** |
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74 | * Reset the internal state. Must be called if input stream is |
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75 | * modified externally to this class |
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76 | */ |
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77 | Void reset() |
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78 | { |
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79 | m_NumFutureBytes = 0; |
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80 | m_FutureBytes = 0; |
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81 | } |
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82 | |
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83 | /** |
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84 | * returns true if an EOF will be encountered within the next |
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85 | * n bytes. |
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86 | */ |
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87 | Bool eofBeforeNBytes(UInt n) |
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88 | { |
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89 | assert(n <= 4); |
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90 | if (m_NumFutureBytes >= n) |
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91 | { |
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92 | return false; |
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93 | } |
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94 | |
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95 | n -= m_NumFutureBytes; |
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96 | try |
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97 | { |
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98 | for (UInt i = 0; i < n; i++) |
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99 | { |
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100 | m_FutureBytes = (m_FutureBytes << 8) | m_Input.get(); |
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101 | m_NumFutureBytes++; |
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102 | } |
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103 | } |
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104 | catch (...) |
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105 | { |
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106 | return true; |
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107 | } |
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108 | return false; |
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109 | } |
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110 | |
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111 | /** |
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112 | * return the next n bytes in the stream without advancing |
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113 | * the stream pointer. |
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114 | * |
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115 | * Returns: an unsigned integer representing an n byte bigendian |
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116 | * word. |
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117 | * |
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118 | * If an attempt is made to read past EOF, an n-byte word is |
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119 | * returned, but the portion that required input bytes beyond EOF |
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120 | * is undefined. |
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121 | * |
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122 | */ |
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123 | uint32_t peekBytes(UInt n) |
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124 | { |
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125 | eofBeforeNBytes(n); |
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126 | return m_FutureBytes >> 8*(m_NumFutureBytes - n); |
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127 | } |
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128 | |
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129 | /** |
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130 | * consume and return one byte from the input. |
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131 | * |
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132 | * If bytestream is already at EOF prior to a call to readByte(), |
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133 | * an exception std::ios_base::failure is thrown. |
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134 | */ |
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135 | uint8_t readByte() |
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136 | { |
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137 | if (!m_NumFutureBytes) |
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138 | { |
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139 | uint8_t byte = m_Input.get(); |
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140 | return byte; |
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141 | } |
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142 | m_NumFutureBytes--; |
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143 | uint8_t wanted_byte = m_FutureBytes >> 8*m_NumFutureBytes; |
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144 | m_FutureBytes &= ~(0xff << 8*m_NumFutureBytes); |
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145 | return wanted_byte; |
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146 | } |
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147 | |
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148 | /** |
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149 | * consume and return n bytes from the input. n bytes from |
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150 | * bytestream are interpreted as bigendian when assembling |
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151 | * the return value. |
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152 | */ |
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153 | uint32_t readBytes(UInt n) |
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154 | { |
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155 | uint32_t val = 0; |
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156 | for (UInt i = 0; i < n; i++) |
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157 | { |
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158 | val = (val << 8) | readByte(); |
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159 | } |
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160 | return val; |
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161 | } |
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162 | |
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163 | #if RExt__DECODER_DEBUG_BIT_STATISTICS |
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164 | UInt GetNumBufferedBytes() const { return m_NumFutureBytes; } |
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165 | #endif |
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166 | |
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167 | private: |
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168 | UInt m_NumFutureBytes; /* number of valid bytes in m_FutureBytes */ |
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169 | uint32_t m_FutureBytes; /* bytes that have been peeked */ |
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170 | std::istream& m_Input; /* Input stream to read from */ |
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171 | }; |
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172 | |
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173 | /** |
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174 | * Statistics associated with AnnexB bytestreams |
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175 | */ |
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176 | struct AnnexBStats |
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177 | { |
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178 | UInt m_numLeadingZero8BitsBytes; |
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179 | UInt m_numZeroByteBytes; |
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180 | UInt m_numStartCodePrefixBytes; |
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181 | UInt m_numBytesInNALUnit; |
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182 | UInt m_numTrailingZero8BitsBytes; |
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183 | |
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184 | AnnexBStats& operator+=(const AnnexBStats& rhs) |
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185 | { |
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186 | this->m_numLeadingZero8BitsBytes += rhs.m_numLeadingZero8BitsBytes; |
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187 | this->m_numZeroByteBytes += rhs.m_numZeroByteBytes; |
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188 | this->m_numStartCodePrefixBytes += rhs.m_numStartCodePrefixBytes; |
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189 | this->m_numBytesInNALUnit += rhs.m_numBytesInNALUnit; |
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190 | this->m_numTrailingZero8BitsBytes += rhs.m_numTrailingZero8BitsBytes; |
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191 | return *this; |
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192 | } |
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193 | }; |
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194 | |
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195 | Bool byteStreamNALUnit(InputByteStream& bs, std::vector<uint8_t>& nalUnit, AnnexBStats& stats); |
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196 | |
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197 | //! \} |
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198 | |
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199 | #endif |
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