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 extern const SINT16 sbc_enc_as16Offset4[4][4]; 32 extern const SINT16 sbc_enc_as16Offset8[4][8]; 33 34 /**************************************************************************** 35 * BitAlloc - Calculates the required number of bits for the given scale factor 36 * and the number of subbands. 37 * 38 * RETURNS : N/A 39 */ 40 41 void sbc_enc_bit_alloc_ste(SBC_ENC_PARAMS *pstrCodecParams) 42 { 43 /* CAUTIOM -> mips optim for arm 32 require to use SINT32 instead of SINT16 */ 44 /* Do not change variable type or name */ 45 SINT32 s32MaxBitNeed; /*to store the max bits needed per sb*/ 46 SINT32 s32BitCount; /*the used number of bits*/ 47 SINT32 s32SliceCount; /*to store hwo many slices can be put in bitpool*/ 48 SINT32 s32BitSlice; /*number of bitslices in bitpool*/ 49 SINT32 s32Sb; /*counter for sub-band*/ 50 SINT32 s32Ch; /*counter for channel*/ 51 SINT16 *ps16BitNeed; /*temp memory to store required number of bits*/ 52 SINT32 s32Loudness; /*used in Loudness calculation*/ 53 SINT16 *ps16GenBufPtr,*pas16ScaleFactor; 54 SINT16 *ps16GenArrPtr; 55 SINT16 *ps16GenTabPtr; 56 SINT32 s32NumOfSubBands = pstrCodecParams->s16NumOfSubBands; 57 SINT32 s32BitPool = pstrCodecParams->s16BitPool; 58 59 /* bitneed values are derived from scale factor */ 60 if (pstrCodecParams->s16AllocationMethod == SBC_SNR) 61 { 62 ps16BitNeed = pstrCodecParams->as16ScaleFactor; 63 s32MaxBitNeed = pstrCodecParams->s16MaxBitNeed; 64 } 65 else 66 { 67 ps16BitNeed = pstrCodecParams->s16ScartchMemForBitAlloc; 68 pas16ScaleFactor=pstrCodecParams->as16ScaleFactor; 69 s32MaxBitNeed = 0; 70 ps16GenBufPtr = ps16BitNeed; 71 for (s32Ch = 0; s32Ch < 2; s32Ch++) 72 { 73 if (s32NumOfSubBands == 4) 74 { 75 ps16GenTabPtr = (SINT16 *)sbc_enc_as16Offset4[pstrCodecParams->s16SamplingFreq]; 76 } 77 else 78 { 79 ps16GenTabPtr = (SINT16 *)sbc_enc_as16Offset8[pstrCodecParams->s16SamplingFreq]; 80 } 81 82 for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) 83 { 84 if (*pas16ScaleFactor == 0) 85 *ps16GenBufPtr = -5; 86 else 87 { 88 s32Loudness = (SINT32)(*pas16ScaleFactor - *ps16GenTabPtr); 89 90 if (s32Loudness > 0) 91 *ps16GenBufPtr = (SINT16)(s32Loudness >> 1); 92 else 93 *ps16GenBufPtr = (SINT16)s32Loudness; 94 } 95 96 if (*ps16GenBufPtr > s32MaxBitNeed) 97 s32MaxBitNeed = *ps16GenBufPtr; 98 pas16ScaleFactor++; 99 ps16GenBufPtr++; 100 ps16GenTabPtr++; 101 } 102 } 103 } 104 105 /* iterative process to find out hwo many bitslices fit into the bitpool */ 106 s32BitSlice = s32MaxBitNeed + 1; 107 s32BitCount = s32BitPool; 108 s32SliceCount = 0; 109 do 110 { 111 s32BitSlice --; 112 s32BitCount -= s32SliceCount; 113 s32SliceCount = 0; 114 ps16GenBufPtr = ps16BitNeed; 115 116 for (s32Sb = 0; s32Sb < 2*s32NumOfSubBands; s32Sb++) 117 { 118 if ( (*ps16GenBufPtr >= s32BitSlice + 1) && (*ps16GenBufPtr < s32BitSlice + 16) ) 119 { 120 if (*(ps16GenBufPtr) == s32BitSlice+1) 121 s32SliceCount += 2; 122 else 123 s32SliceCount++; 124 } 125 ps16GenBufPtr++; 126 } 127 } while (s32BitCount-s32SliceCount>0); 128 129 if (s32BitCount-s32SliceCount == 0) 130 { 131 s32BitCount -= s32SliceCount; 132 s32BitSlice --; 133 } 134 135 /* Bits are distributed until the last bitslice is reached */ 136 ps16GenBufPtr = ps16BitNeed; 137 ps16GenArrPtr = pstrCodecParams->as16Bits; 138 for (s32Ch = 0; s32Ch < 2; s32Ch++) 139 { 140 for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) 141 { 142 if (*ps16GenBufPtr < s32BitSlice+2) 143 *ps16GenArrPtr = 0; 144 else 145 *ps16GenArrPtr = ((*(ps16GenBufPtr)-s32BitSlice) < 16) ? 146 (SINT16)(*(ps16GenBufPtr)-s32BitSlice):16; 147 ps16GenBufPtr++; 148 ps16GenArrPtr++; 149 } 150 } 151 152 /* the remaining bits are allocated starting at subband 0 */ 153 s32Ch=0; 154 s32Sb=0; 155 ps16GenBufPtr = ps16BitNeed; 156 ps16GenArrPtr -= 2*s32NumOfSubBands; 157 158 while ( (s32BitCount > 0) && (s32Sb < s32NumOfSubBands) ) 159 { 160 if ( (*(ps16GenArrPtr) >= 2) && (*(ps16GenArrPtr) < 16) ) 161 { 162 (*(ps16GenArrPtr))++; 163 s32BitCount--; 164 } 165 else if ((*ps16GenBufPtr == s32BitSlice+1) && (s32BitCount > 1)) 166 { 167 *(ps16GenArrPtr) = 2; 168 s32BitCount -= 2; 169 } 170 if(s32Ch == 1) 171 { 172 s32Ch = 0; 173 s32Sb++; 174 ps16GenBufPtr = ps16BitNeed+s32Sb; 175 ps16GenArrPtr = pstrCodecParams->as16Bits+s32Sb; 176 177 } 178 else 179 { 180 s32Ch =1; 181 ps16GenBufPtr = ps16BitNeed+s32NumOfSubBands+s32Sb; 182 ps16GenArrPtr = pstrCodecParams->as16Bits+s32NumOfSubBands+s32Sb; 183 } 184 } 185 186 s32Ch=0; 187 s32Sb=0; 188 ps16GenArrPtr = pstrCodecParams->as16Bits; 189 190 while ((s32BitCount >0) && (s32Sb < s32NumOfSubBands)) 191 { 192 if(*(ps16GenArrPtr) < 16) 193 { 194 (*(ps16GenArrPtr))++; 195 s32BitCount--; 196 } 197 if (s32Ch == 1) 198 { 199 s32Ch = 0; 200 s32Sb++; 201 ps16GenArrPtr = pstrCodecParams->as16Bits+s32Sb; 202 } 203 else 204 { 205 s32Ch = 1; 206 ps16GenArrPtr = pstrCodecParams->as16Bits+s32NumOfSubBands+s32Sb; 207 } 208 } 209 } 210 211 /*End of BitAlloc() function*/ 212 213
