1 /* /////////////////////////////////////////////////////////////////////// 2 // 3 // INTEL CORPORATION PROPRIETARY INFORMATION 4 // This software is supplied under the terms of a license agreement or 5 // nondisclosure agreement with Intel Corporation and may not be copied 6 // or disclosed except in accordance with the terms of that agreement. 7 // Copyright (c) 2001-2006 Intel Corporation. All Rights Reserved. 8 // 9 // Description: h264 bistream decoding 10 // 11 ///////////////////////////////////////////////////////////////////////*/ 12 13 14 #include "h264.h" 15 #include "h264parse.h" 16 #include "viddec_parser_ops.h" 17 18 19 20 21 22 /** 23 get_codeNum :Get codenum based on sec 9.1 of H264 spec. 24 @param cxt : Buffer adress & size are part inputs, the cxt is updated 25 with codeNum & sign on sucess. 26 Assumption: codeNum is a max of 32 bits 27 28 @retval 1 : Sucessfuly found a code num, cxt is updated with codeNum, sign, and size of code. 29 @retval 0 : Couldn't find a code in the current buffer. 30 be freed. 31 */ 32 33 uint32_t h264_get_codeNum(void *parent, h264_Info* pInfo) 34 { 35 int32_t leadingZeroBits= 0; 36 uint32_t temp = 0, match = 0, noOfBits = 0, count = 0; 37 uint32_t codeNum =0; 38 uint32_t bits_offset =0, byte_offset =0; 39 uint8_t is_emul =0; 40 uint8_t is_first_byte = 1; 41 uint32_t length =0; 42 uint32_t bits_need_add_in_first_byte =0; 43 int32_t bits_operation_result=0; 44 45 //remove warning 46 pInfo = pInfo; 47 48 ////// Step 1: parse through zero bits until we find a bit with value 1. 49 viddec_pm_get_au_pos(parent, &bits_offset, &byte_offset, &is_emul); 50 51 52 while(!match) 53 { 54 if ((bits_offset != 0) && ( is_first_byte == 1)) 55 { 56 //we handle byte at a time, if we have offset then for first 57 // byte handle only 8 - offset bits 58 noOfBits = (uint8_t)(8 - bits_offset); 59 bits_operation_result = viddec_pm_peek_bits(parent, &temp, noOfBits); 60 61 62 temp = (temp << bits_offset); 63 if(temp!=0) 64 { 65 bits_need_add_in_first_byte = bits_offset; 66 } 67 is_first_byte =0; 68 } 69 else 70 { 71 noOfBits = 8;/* always 8 bits as we read a byte at a time */ 72 bits_operation_result = viddec_pm_peek_bits(parent, &temp, 8); 73 74 } 75 76 if(-1==bits_operation_result) 77 { 78 return MAX_INT32_VALUE; 79 } 80 81 if(temp != 0) 82 { 83 // if byte!=0 we have at least one bit with value 1. 84 count=1; 85 while(((temp & 0x80) != 0x80) && (count <= noOfBits)) 86 { 87 count++; 88 temp = temp <<1; 89 } 90 //At this point we get the bit position of 1 in current byte(count). 91 92 match = 1; 93 leadingZeroBits += count; 94 } 95 else 96 { 97 // we don't have a 1 in current byte 98 leadingZeroBits += noOfBits; 99 } 100 101 if(!match) 102 { 103 //actually move the bitoff by viddec_pm_get_bits 104 viddec_pm_get_bits(parent, &temp, noOfBits); 105 } 106 else 107 { 108 //actually move the bitoff by viddec_pm_get_bits 109 viddec_pm_get_bits(parent, &temp, count); 110 } 111 112 } 113 ////// step 2: Now read the next (leadingZeroBits-1) bits to get the encoded value. 114 115 116 if(match) 117 { 118 119 viddec_pm_get_au_pos(parent, &bits_offset, &byte_offset, &is_emul); 120 /* bit position in current byte */ 121 //count = (uint8_t)((leadingZeroBits + bits_offset)& 0x7); 122 count = ((count + bits_need_add_in_first_byte)& 0x7); 123 124 leadingZeroBits --; 125 length = leadingZeroBits; 126 codeNum = 0; 127 noOfBits = 8 - count; 128 129 130 while(leadingZeroBits > 0) 131 { 132 if(noOfBits < (uint32_t)leadingZeroBits) 133 { 134 viddec_pm_get_bits(parent, &temp, noOfBits); 135 136 137 codeNum = (codeNum << noOfBits) | temp; 138 leadingZeroBits -= noOfBits; 139 } 140 else 141 { 142 viddec_pm_get_bits(parent, &temp, leadingZeroBits); 143 144 codeNum = (codeNum << leadingZeroBits) | temp; 145 leadingZeroBits = 0; 146 } 147 148 149 noOfBits = 8; 150 } 151 // update codeNum = 2 ** (leadingZeroBits) -1 + read_bits(leadingZeroBits). 152 codeNum = codeNum + (1 << length) -1; 153 154 } 155 156 viddec_pm_get_au_pos(parent, &bits_offset, &byte_offset, &is_emul); 157 if(bits_offset!=0) 158 { 159 viddec_pm_peek_bits(parent, &temp, 8-bits_offset); 160 } 161 162 return codeNum; 163 } 164 165 166 /*---------------------------------------*/ 167 /*---------------------------------------*/ 168 int32_t h264_GetVLCElement(void *parent, h264_Info* pInfo, uint8_t bIsSigned) 169 { 170 int32_t sval = 0; 171 signed char sign; 172 173 sval = h264_get_codeNum(parent , pInfo); 174 175 if(bIsSigned) //get signed integer golomb code else the value is unsigned 176 { 177 sign = (sval & 0x1)?1:-1; 178 sval = (sval +1) >> 1; 179 sval = sval * sign; 180 } 181 182 return sval; 183 } // Ipp32s H264Bitstream::GetVLCElement(bool bIsSigned) 184 185 /// 186 /// Check whether more RBSP data left in current NAL 187 /// 188 uint8_t h264_More_RBSP_Data(void *parent, h264_Info * pInfo) 189 { 190 uint8_t cnt = 0; 191 192 uint8_t is_emul =0; 193 uint8_t cur_byte = 0; 194 int32_t shift_bits =0; 195 uint32_t ctr_bit = 0; 196 uint32_t bits_offset =0, byte_offset =0; 197 198 //remove warning 199 pInfo = pInfo; 200 201 if (!viddec_pm_is_nomoredata(parent)) 202 return 1; 203 204 viddec_pm_get_au_pos(parent, &bits_offset, &byte_offset, &is_emul); 205 206 shift_bits = 7-bits_offset; 207 208 // read one byte 209 viddec_pm_get_cur_byte(parent, &cur_byte); 210 211 ctr_bit = ((cur_byte)>> (shift_bits--)) & 0x01; 212 213 // a stop bit has to be one 214 if (ctr_bit==0) 215 return 1; 216 217 while (shift_bits>=0 && !cnt) 218 { 219 cnt |= (((cur_byte)>> (shift_bits--)) & 0x01); // set up control bit 220 } 221 222 return (cnt); 223 } 224 225 226 227 ///////////// EOF///////////////////// 228 229
