1 /****************************************************************************** 2 * 3 * Copyright (C) 1999-2012 Broadcom Corporation 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at: 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 ******************************************************************************/ 18 19 /****************************************************************************** 20 * 21 * This file contains the code for bit allocation algorithm. It calculates 22 * the number of bits required for the encoded stream of data. 23 * 24 ******************************************************************************/ 25 26 /*Includes*/ 27 #include "sbc_encoder.h" 28 #include "sbc_enc_func_declare.h" 29 30 /*global arrays*/ 31 const SINT16 sbc_enc_as16Offset4[4][4] = { {-1, 0, 0, 0}, {-2, 0, 0, 1}, 32 {-2, 0, 0, 1}, {-2, 0, 0, 1} }; 33 const SINT16 sbc_enc_as16Offset8[4][8] = { {-2, 0, 0, 0, 0, 0, 0, 1}, 34 {-3, 0, 0, 0, 0, 0, 1, 2}, 35 {-4, 0, 0, 0, 0, 0, 1, 2}, 36 {-4, 0, 0, 0, 0, 0, 1, 2} }; 37 38 /**************************************************************************** 39 * BitAlloc - Calculates the required number of bits for the given scale factor 40 * and the number of subbands. 41 * 42 * RETURNS : N/A 43 */ 44 45 void sbc_enc_bit_alloc_mono(SBC_ENC_PARAMS *pstrCodecParams) 46 { 47 SINT32 s32MaxBitNeed; /*to store the max bits needed per sb*/ 48 SINT32 s32BitCount; /*the used number of bits*/ 49 SINT32 s32SliceCount; /*to store hwo many slices can be put in bitpool*/ 50 SINT32 s32BitSlice; /*number of bitslices in bitpool*/ 51 SINT32 s32Sb; /*counter for sub-band*/ 52 SINT32 s32Ch; /*counter for channel*/ 53 SINT16 *ps16BitNeed; /*temp memory to store required number of bits*/ 54 SINT32 s32Loudness; /*used in Loudness calculation*/ 55 SINT16 *ps16GenBufPtr; 56 SINT16 *ps16GenArrPtr; 57 SINT16 *ps16GenTabPtr; 58 SINT32 s32NumOfSubBands = pstrCodecParams->s16NumOfSubBands; 59 60 ps16BitNeed = pstrCodecParams->s16ScartchMemForBitAlloc; 61 62 for (s32Ch = 0; s32Ch < pstrCodecParams->s16NumOfChannels; s32Ch++) 63 { 64 ps16GenBufPtr = ps16BitNeed + s32Ch*s32NumOfSubBands; 65 ps16GenArrPtr = pstrCodecParams->as16Bits+s32Ch*SBC_MAX_NUM_OF_SUBBANDS; 66 67 /* bitneed values are derived from scale factor */ 68 if (pstrCodecParams->s16AllocationMethod == SBC_SNR) 69 { 70 ps16BitNeed = pstrCodecParams->as16ScaleFactor; 71 ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; 72 } 73 else 74 { 75 ps16GenBufPtr = ps16BitNeed + s32Ch*s32NumOfSubBands; 76 if(s32NumOfSubBands == 4) 77 { 78 ps16GenTabPtr = (SINT16 *) 79 sbc_enc_as16Offset4[pstrCodecParams->s16SamplingFreq]; 80 } 81 else 82 { 83 ps16GenTabPtr = (SINT16 *) 84 sbc_enc_as16Offset8[pstrCodecParams->s16SamplingFreq]; 85 } 86 for(s32Sb=0; s32Sb<s32NumOfSubBands; s32Sb++) 87 { 88 if(pstrCodecParams->as16ScaleFactor[s32Ch*s32NumOfSubBands+s32Sb] == 0) 89 *(ps16GenBufPtr) = -5; 90 else 91 { 92 s32Loudness = 93 (SINT32)(pstrCodecParams->as16ScaleFactor[s32Ch*s32NumOfSubBands+s32Sb] 94 - *ps16GenTabPtr); 95 if(s32Loudness > 0) 96 *(ps16GenBufPtr) = (SINT16)(s32Loudness >>1); 97 else 98 *(ps16GenBufPtr) = (SINT16)s32Loudness; 99 } 100 ps16GenBufPtr++; 101 ps16GenTabPtr++; 102 } 103 104 } 105 106 /* max bitneed index is searched*/ 107 s32MaxBitNeed = 0; 108 ps16GenBufPtr = ps16BitNeed + s32Ch*s32NumOfSubBands; 109 for(s32Sb=0; s32Sb<s32NumOfSubBands; s32Sb++) 110 { 111 if( *(ps16GenBufPtr) > s32MaxBitNeed) 112 s32MaxBitNeed = *(ps16GenBufPtr); 113 114 ps16GenBufPtr++; 115 } 116 ps16GenBufPtr = ps16BitNeed + s32Ch*s32NumOfSubBands; 117 /*iterative process to find hwo many bitslices fit into the bitpool*/ 118 s32BitSlice = s32MaxBitNeed + 1; 119 s32BitCount = pstrCodecParams->s16BitPool; 120 s32SliceCount = 0; 121 do 122 { 123 s32BitSlice --; 124 s32BitCount -= s32SliceCount; 125 s32SliceCount = 0; 126 127 for(s32Sb=0; s32Sb<s32NumOfSubBands; s32Sb++) 128 { 129 if( (((*ps16GenBufPtr-s32BitSlice)< 16) && (*ps16GenBufPtr-s32BitSlice) >= 1)) 130 { 131 if((*ps16GenBufPtr-s32BitSlice) == 1) 132 s32SliceCount+=2; 133 else 134 s32SliceCount++; 135 } 136 ps16GenBufPtr++; 137 138 }/*end of for*/ 139 ps16GenBufPtr = ps16BitNeed + s32Ch*s32NumOfSubBands; 140 }while(s32BitCount-s32SliceCount>0); 141 142 if(s32BitCount == 0) 143 { 144 s32BitCount -= s32SliceCount; 145 s32BitSlice --; 146 } 147 148 /*Bits are distributed until the last bitslice is reached*/ 149 ps16GenArrPtr = pstrCodecParams->as16Bits+s32Ch*s32NumOfSubBands; 150 ps16GenBufPtr = ps16BitNeed + s32Ch*s32NumOfSubBands; 151 for(s32Sb=0; s32Sb<s32NumOfSubBands; s32Sb++) 152 { 153 if(*(ps16GenBufPtr) < s32BitSlice+2) 154 *(ps16GenArrPtr) = 0; 155 else 156 *(ps16GenArrPtr) = ((*(ps16GenBufPtr)-s32BitSlice)<16) ? 157 (SINT16)(*(ps16GenBufPtr)-s32BitSlice) : 16; 158 159 ps16GenBufPtr++; 160 ps16GenArrPtr++; 161 } 162 ps16GenArrPtr = pstrCodecParams->as16Bits+s32Ch*s32NumOfSubBands; 163 ps16GenBufPtr = ps16BitNeed + s32Ch*s32NumOfSubBands; 164 /*the remaining bits are allocated starting at subband 0*/ 165 s32Sb=0; 166 while( (s32BitCount > 0) && (s32Sb < s32NumOfSubBands) ) 167 { 168 if( (*(ps16GenArrPtr) >= 2) && (*(ps16GenArrPtr) < 16) ) 169 { 170 (*(ps16GenArrPtr))++; 171 s32BitCount--; 172 } 173 else if( (*(ps16GenBufPtr) == s32BitSlice+1) && 174 (s32BitCount > 1) ) 175 { 176 *(ps16GenArrPtr) = 2; 177 s32BitCount -= 2; 178 } 179 s32Sb++; 180 ps16GenArrPtr++; 181 ps16GenBufPtr++; 182 } 183 ps16GenArrPtr = pstrCodecParams->as16Bits+s32Ch*s32NumOfSubBands; 184 185 186 s32Sb=0; 187 while( (s32BitCount > 0) && (s32Sb < s32NumOfSubBands) ) 188 { 189 if( *(ps16GenArrPtr) < 16) 190 { 191 (*(ps16GenArrPtr))++; 192 s32BitCount--; 193 } 194 s32Sb++; 195 ps16GenArrPtr++; 196 } 197 } 198 } 199 /*End of BitAlloc() function*/ 200
