| /****************************************************************************** |
| * |
| * Copyright 1999-2012 Broadcom Corporation |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at: |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| ******************************************************************************/ |
| |
| /****************************************************************************** |
| * |
| * This file contains the code for bit allocation algorithm. It calculates |
| * the number of bits required for the encoded stream of data. |
| * |
| ******************************************************************************/ |
| |
| /*Includes*/ |
| #include "sbc_enc_func_declare.h" |
| #include "sbc_encoder.h" |
| |
| /*global arrays*/ |
| const int16_t sbc_enc_as16Offset4[4][4] = { |
| {-1, 0, 0, 0}, {-2, 0, 0, 1}, {-2, 0, 0, 1}, {-2, 0, 0, 1}}; |
| const int16_t sbc_enc_as16Offset8[4][8] = {{-2, 0, 0, 0, 0, 0, 0, 1}, |
| {-3, 0, 0, 0, 0, 0, 1, 2}, |
| {-4, 0, 0, 0, 0, 0, 1, 2}, |
| {-4, 0, 0, 0, 0, 0, 1, 2}}; |
| |
| /**************************************************************************** |
| * BitAlloc - Calculates the required number of bits for the given scale factor |
| * and the number of subbands. |
| * |
| * RETURNS : N/A |
| */ |
| |
| void sbc_enc_bit_alloc_mono(SBC_ENC_PARAMS* pstrCodecParams) { |
| int32_t s32MaxBitNeed; /*to store the max bits needed per sb*/ |
| int32_t s32BitCount; /*the used number of bits*/ |
| int32_t s32SliceCount; /*to store hwo many slices can be put in bitpool*/ |
| int32_t s32BitSlice; /*number of bitslices in bitpool*/ |
| int32_t s32Sb; /*counter for sub-band*/ |
| int32_t s32Ch; /*counter for channel*/ |
| int16_t* ps16BitNeed; /*temp memory to store required number of bits*/ |
| int32_t s32Loudness; /*used in Loudness calculation*/ |
| int16_t* ps16GenBufPtr; |
| int16_t* ps16GenArrPtr; |
| int16_t* ps16GenTabPtr; |
| int32_t s32NumOfSubBands = pstrCodecParams->s16NumOfSubBands; |
| |
| ps16BitNeed = pstrCodecParams->s16ScartchMemForBitAlloc; |
| |
| for (s32Ch = 0; s32Ch < pstrCodecParams->s16NumOfChannels; s32Ch++) { |
| ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; |
| ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * SBC_MAX_NUM_OF_SUBBANDS; |
| |
| /* bitneed values are derived from scale factor */ |
| if (pstrCodecParams->s16AllocationMethod == SBC_SNR) { |
| ps16BitNeed = pstrCodecParams->as16ScaleFactor; |
| ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; |
| } else { |
| ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; |
| if (s32NumOfSubBands == 4) { |
| ps16GenTabPtr = |
| (int16_t*)sbc_enc_as16Offset4[pstrCodecParams->s16SamplingFreq]; |
| } else { |
| ps16GenTabPtr = |
| (int16_t*)sbc_enc_as16Offset8[pstrCodecParams->s16SamplingFreq]; |
| } |
| for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) { |
| if (pstrCodecParams |
| ->as16ScaleFactor[s32Ch * s32NumOfSubBands + s32Sb] == 0) |
| *(ps16GenBufPtr) = -5; |
| else { |
| s32Loudness = (int32_t)( |
| pstrCodecParams |
| ->as16ScaleFactor[s32Ch * s32NumOfSubBands + s32Sb] - |
| *ps16GenTabPtr); |
| if (s32Loudness > 0) |
| *(ps16GenBufPtr) = (int16_t)(s32Loudness >> 1); |
| else |
| *(ps16GenBufPtr) = (int16_t)s32Loudness; |
| } |
| ps16GenBufPtr++; |
| ps16GenTabPtr++; |
| } |
| } |
| |
| /* max bitneed index is searched*/ |
| s32MaxBitNeed = 0; |
| ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; |
| for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) { |
| if (*(ps16GenBufPtr) > s32MaxBitNeed) s32MaxBitNeed = *(ps16GenBufPtr); |
| |
| ps16GenBufPtr++; |
| } |
| ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; |
| /*iterative process to find hwo many bitslices fit into the bitpool*/ |
| s32BitSlice = s32MaxBitNeed + 1; |
| s32BitCount = pstrCodecParams->s16BitPool; |
| s32SliceCount = 0; |
| do { |
| s32BitSlice--; |
| s32BitCount -= s32SliceCount; |
| s32SliceCount = 0; |
| |
| for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) { |
| if ((((*ps16GenBufPtr - s32BitSlice) < 16) && |
| (*ps16GenBufPtr - s32BitSlice) >= 1)) { |
| if ((*ps16GenBufPtr - s32BitSlice) == 1) |
| s32SliceCount += 2; |
| else |
| s32SliceCount++; |
| } |
| ps16GenBufPtr++; |
| |
| } /*end of for*/ |
| ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; |
| } while (s32BitCount - s32SliceCount > 0); |
| |
| if (s32BitCount == 0) { |
| s32BitCount -= s32SliceCount; |
| s32BitSlice--; |
| } |
| |
| /*Bits are distributed until the last bitslice is reached*/ |
| ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * s32NumOfSubBands; |
| ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; |
| for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) { |
| if (*(ps16GenBufPtr) < s32BitSlice + 2) |
| *(ps16GenArrPtr) = 0; |
| else |
| *(ps16GenArrPtr) = ((*(ps16GenBufPtr)-s32BitSlice) < 16) |
| ? (int16_t)(*(ps16GenBufPtr)-s32BitSlice) |
| : 16; |
| |
| ps16GenBufPtr++; |
| ps16GenArrPtr++; |
| } |
| ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * s32NumOfSubBands; |
| ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands; |
| /*the remaining bits are allocated starting at subband 0*/ |
| s32Sb = 0; |
| while ((s32BitCount > 0) && (s32Sb < s32NumOfSubBands)) { |
| if ((*(ps16GenArrPtr) >= 2) && (*(ps16GenArrPtr) < 16)) { |
| (*(ps16GenArrPtr))++; |
| s32BitCount--; |
| } else if ((*(ps16GenBufPtr) == s32BitSlice + 1) && (s32BitCount > 1)) { |
| *(ps16GenArrPtr) = 2; |
| s32BitCount -= 2; |
| } |
| s32Sb++; |
| ps16GenArrPtr++; |
| ps16GenBufPtr++; |
| } |
| ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * s32NumOfSubBands; |
| |
| s32Sb = 0; |
| while ((s32BitCount > 0) && (s32Sb < s32NumOfSubBands)) { |
| if (*(ps16GenArrPtr) < 16) { |
| (*(ps16GenArrPtr))++; |
| s32BitCount--; |
| } |
| s32Sb++; |
| ps16GenArrPtr++; |
| } |
| } |
| } |
| /*End of BitAlloc() function*/ |