189 lines
7.2 KiB
C
189 lines
7.2 KiB
C
/******************************************************************************
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*
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* Copyright (C) 1999-2012 Broadcom Corporation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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******************************************************************************/
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/******************************************************************************
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*
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* This file contains the code for bit allocation algorithm. It calculates
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* the number of bits required for the encoded stream of data.
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*
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******************************************************************************/
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/*Includes*/
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#include "bt_target.h"
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#include "sbc_encoder.h"
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#include "sbc_enc_func_declare.h"
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#if (defined(SBC_ENC_INCLUDED) && SBC_ENC_INCLUDED == TRUE)
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/*global arrays*/
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const SINT16 sbc_enc_as16Offset4[4][4] = { { -1, 0, 0, 0}, { -2, 0, 0, 1},
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{ -2, 0, 0, 1}, { -2, 0, 0, 1}
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};
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const SINT16 sbc_enc_as16Offset8[4][8] = { { -2, 0, 0, 0, 0, 0, 0, 1},
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{ -3, 0, 0, 0, 0, 0, 1, 2},
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{ -4, 0, 0, 0, 0, 0, 1, 2},
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{ -4, 0, 0, 0, 0, 0, 1, 2}
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};
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/****************************************************************************
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* BitAlloc - Calculates the required number of bits for the given scale factor
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* and the number of subbands.
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*
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* RETURNS : N/A
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*/
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void sbc_enc_bit_alloc_mono(SBC_ENC_PARAMS *pstrCodecParams)
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{
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SINT32 s32MaxBitNeed; /*to store the max bits needed per sb*/
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SINT32 s32BitCount; /*the used number of bits*/
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SINT32 s32SliceCount; /*to store hwo many slices can be put in bitpool*/
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SINT32 s32BitSlice; /*number of bitslices in bitpool*/
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SINT32 s32Sb; /*counter for sub-band*/
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SINT32 s32Ch; /*counter for channel*/
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SINT16 *ps16BitNeed; /*temp memory to store required number of bits*/
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SINT32 s32Loudness; /*used in Loudness calculation*/
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SINT16 *ps16GenBufPtr;
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SINT16 *ps16GenArrPtr;
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SINT16 *ps16GenTabPtr;
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SINT32 s32NumOfSubBands = pstrCodecParams->s16NumOfSubBands;
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ps16BitNeed = pstrCodecParams->s16ScartchMemForBitAlloc;
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for (s32Ch = 0; s32Ch < pstrCodecParams->s16NumOfChannels; s32Ch++) {
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ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands;
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ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * SBC_MAX_NUM_OF_SUBBANDS;
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/* bitneed values are derived from scale factor */
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if (pstrCodecParams->s16AllocationMethod == SBC_SNR) {
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ps16BitNeed = pstrCodecParams->as16ScaleFactor;
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ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands;
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} else {
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ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands;
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if (s32NumOfSubBands == 4) {
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ps16GenTabPtr = (SINT16 *)
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sbc_enc_as16Offset4[pstrCodecParams->s16SamplingFreq];
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} else {
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ps16GenTabPtr = (SINT16 *)
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sbc_enc_as16Offset8[pstrCodecParams->s16SamplingFreq];
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}
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for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) {
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if (pstrCodecParams->as16ScaleFactor[s32Ch * s32NumOfSubBands + s32Sb] == 0) {
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*(ps16GenBufPtr) = -5;
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} else {
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s32Loudness =
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(SINT32)(pstrCodecParams->as16ScaleFactor[s32Ch * s32NumOfSubBands + s32Sb]
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- *ps16GenTabPtr);
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if (s32Loudness > 0) {
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*(ps16GenBufPtr) = (SINT16)(s32Loudness >> 1);
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} else {
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*(ps16GenBufPtr) = (SINT16)s32Loudness;
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}
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}
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ps16GenBufPtr++;
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ps16GenTabPtr++;
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}
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}
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/* max bitneed index is searched*/
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s32MaxBitNeed = 0;
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ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands;
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for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) {
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if ( *(ps16GenBufPtr) > s32MaxBitNeed) {
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s32MaxBitNeed = *(ps16GenBufPtr);
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}
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ps16GenBufPtr++;
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}
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ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands;
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/*iterative process to find hwo many bitslices fit into the bitpool*/
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s32BitSlice = s32MaxBitNeed + 1;
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s32BitCount = pstrCodecParams->s16BitPool;
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s32SliceCount = 0;
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do {
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s32BitSlice --;
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s32BitCount -= s32SliceCount;
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s32SliceCount = 0;
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for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) {
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if ( (((*ps16GenBufPtr - s32BitSlice) < 16) && (*ps16GenBufPtr - s32BitSlice) >= 1)) {
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if ((*ps16GenBufPtr - s32BitSlice) == 1) {
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s32SliceCount += 2;
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} else {
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s32SliceCount++;
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}
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}
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ps16GenBufPtr++;
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}/*end of for*/
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ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands;
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} while (s32BitCount - s32SliceCount > 0);
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if (s32BitCount == 0) {
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s32BitCount -= s32SliceCount;
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s32BitSlice --;
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}
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/*Bits are distributed until the last bitslice is reached*/
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ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * s32NumOfSubBands;
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ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands;
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for (s32Sb = 0; s32Sb < s32NumOfSubBands; s32Sb++) {
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if (*(ps16GenBufPtr) < s32BitSlice + 2) {
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*(ps16GenArrPtr) = 0;
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} else
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*(ps16GenArrPtr) = ((*(ps16GenBufPtr) - s32BitSlice) < 16) ?
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(SINT16)(*(ps16GenBufPtr) - s32BitSlice) : 16;
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ps16GenBufPtr++;
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ps16GenArrPtr++;
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}
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ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * s32NumOfSubBands;
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ps16GenBufPtr = ps16BitNeed + s32Ch * s32NumOfSubBands;
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/*the remaining bits are allocated starting at subband 0*/
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s32Sb = 0;
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while ( (s32BitCount > 0) && (s32Sb < s32NumOfSubBands) ) {
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if ( (*(ps16GenArrPtr) >= 2) && (*(ps16GenArrPtr) < 16) ) {
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(*(ps16GenArrPtr))++;
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s32BitCount--;
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} else if ( (*(ps16GenBufPtr) == s32BitSlice + 1) &&
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(s32BitCount > 1) ) {
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*(ps16GenArrPtr) = 2;
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s32BitCount -= 2;
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}
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s32Sb++;
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ps16GenArrPtr++;
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ps16GenBufPtr++;
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}
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ps16GenArrPtr = pstrCodecParams->as16Bits + s32Ch * s32NumOfSubBands;
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s32Sb = 0;
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while ( (s32BitCount > 0) && (s32Sb < s32NumOfSubBands) ) {
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if ( *(ps16GenArrPtr) < 16) {
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(*(ps16GenArrPtr))++;
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s32BitCount--;
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}
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s32Sb++;
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ps16GenArrPtr++;
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}
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}
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}
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/*End of BitAlloc() function*/
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#endif /* #if (defined(SBC_ENC_INCLUDED) && SBC_ENC_INCLUDED == TRUE) */
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