1 /****************************************************************************** 2 * 3 * Copyright 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_enc_func_declare.h" 28 #include "sbc_encoder.h" 29 30 /*global arrays*/ 31 const int16_t sbc_enc_as16Offset4[4][4] = { 32 {-1, 0, 0, 0}, {-2, 0, 0, 1}, {-2, 0, 0, 1}, {-2, 0, 0, 1}}; 33 const int16_t 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 int32_t s32MaxBitNeed; /*to store the max bits needed per sb*/ 47 int32_t s32BitCount; /*the used number of bits*/ 48 int32_t s32SliceCount; /*to store hwo many slices can be put in bitpool*/ 49 int32_t s32BitSlice; /*number of bitslices in bitpool*/ 50 int32_t s32Sb; /*counter for sub-band*/ 51 int32_t s32Ch; /*counter for channel*/ 52 int16_t* ps16BitNeed; /*temp memory to store required number of bits*/ 53 int32_t s32Loudness; /*used in Loudness calculation*/ 54 int16_t* ps16GenBufPtr; 55 int16_t* ps16GenArrPtr; 56 int16_t* ps16GenTabPtr; 57 int32_t s32NumOfSubBands = pstrCodecParams->s16NumOfSubBands; 58 59 ps16BitNeed = pstrCodecParams->s16ScartchMemForBitAlloc; 60 61 for (s32Ch = 0; s32Ch < pstrCodecParams->s16NumOfChannels; s32Ch++) { 62 ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; 63 ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * SBC_MAX_NUM_OF_SUBBANDS; 64 65 /* bitneed values are derived from scale factor */ 66 if (pstrCodecParams->s16AllocationMethod == SBC_SNR) { 67 ps16BitNeed = pstrCodecParams->as16ScaleFactor; 68 ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; 69 } else { 70 ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; 71 if (s32NumOfSubBands == 4) { 72 ps16GenTabPtr = 73 (int16_t*)sbc_enc_as16Offset4[pstrCodecParams->s16SamplingFreq]; 74 } else { 75 ps16GenTabPtr = 76 (int16_t*)sbc_enc_as16Offset8[pstrCodecParams->s16SamplingFreq]; 77 } 78 for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) { 79 if (pstrCodecParams 80 ->as16ScaleFactor[s32Ch * s32NumOfSubBands + s32Sb] == 0) 81 *(ps16GenBufPtr) = -5; 82 else { 83 s32Loudness = (int32_t)( 84 pstrCodecParams 85 ->as16ScaleFactor[s32Ch * s32NumOfSubBands + s32Sb] - 86 *ps16GenTabPtr); 87 if (s32Loudness > 0) 88 *(ps16GenBufPtr) = (int16_t)(s32Loudness >> 1); 89 else 90 *(ps16GenBufPtr) = (int16_t)s32Loudness; 91 } 92 ps16GenBufPtr++; 93 ps16GenTabPtr++; 94 } 95 } 96 97 /* max bitneed index is searched*/ 98 s32MaxBitNeed = 0; 99 ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; 100 for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) { 101 if (*(ps16GenBufPtr) > s32MaxBitNeed) s32MaxBitNeed = *(ps16GenBufPtr); 102 103 ps16GenBufPtr++; 104 } 105 ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; 106 /*iterative process to find hwo many bitslices fit into the bitpool*/ 107 s32BitSlice = s32MaxBitNeed + 1; 108 s32BitCount = pstrCodecParams->s16BitPool; 109 s32SliceCount = 0; 110 do { 111 s32BitSlice--; 112 s32BitCount -= s32SliceCount; 113 s32SliceCount = 0; 114 115 for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) { 116 if ((((*ps16GenBufPtr - s32BitSlice) < 16) && 117 (*ps16GenBufPtr - s32BitSlice) >= 1)) { 118 if ((*ps16GenBufPtr - s32BitSlice) == 1) 119 s32SliceCount += 2; 120 else 121 s32SliceCount++; 122 } 123 ps16GenBufPtr++; 124 125 } /*end of for*/ 126 ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; 127 } while (s32BitCount - s32SliceCount > 0); 128 129 if (s32BitCount == 0) { 130 s32BitCount -= s32SliceCount; 131 s32BitSlice--; 132 } 133 134 /*Bits are distributed until the last bitslice is reached*/ 135 ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * s32NumOfSubBands; 136 ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; 137 for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) { 138 if (*(ps16GenBufPtr) < s32BitSlice + 2) 139 *(ps16GenArrPtr) = 0; 140 else 141 *(ps16GenArrPtr) = ((*(ps16GenBufPtr)-s32BitSlice) < 16) 142 ? (int16_t)(*(ps16GenBufPtr)-s32BitSlice) 143 : 16; 144 145 ps16GenBufPtr++; 146 ps16GenArrPtr++; 147 } 148 ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * s32NumOfSubBands; 149 ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; 150 /*the remaining bits are allocated starting at subband 0*/ 151 s32Sb = 0; 152 while ((s32BitCount > 0) && (s32Sb < s32NumOfSubBands)) { 153 if ((*(ps16GenArrPtr) >= 2) && (*(ps16GenArrPtr) < 16)) { 154 (*(ps16GenArrPtr))++; 155 s32BitCount--; 156 } else if ((*(ps16GenBufPtr) == s32BitSlice + 1) && (s32BitCount > 1)) { 157 *(ps16GenArrPtr) = 2; 158 s32BitCount -= 2; 159 } 160 s32Sb++; 161 ps16GenArrPtr++; 162 ps16GenBufPtr++; 163 } 164 ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * s32NumOfSubBands; 165 166 s32Sb = 0; 167 while ((s32BitCount > 0) && (s32Sb < s32NumOfSubBands)) { 168 if (*(ps16GenArrPtr) < 16) { 169 (*(ps16GenArrPtr))++; 170 s32BitCount--; 171 } 172 s32Sb++; 173 ps16GenArrPtr++; 174 } 175 } 176 } 177 /*End of BitAlloc() function*/ 178
