272 lines
8.8 KiB
C
272 lines
8.8 KiB
C
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/*
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* Bluetooth low-complexity, subband codec (SBC)
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*
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* Copyright (C) 2017 Aurelien Jacobs <aurel@gnuage.org>
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* Copyright (C) 2012-2013 Intel Corporation
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* Copyright (C) 2008-2010 Nokia Corporation
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* Copyright (C) 2004-2010 Marcel Holtmann <marcel@holtmann.org>
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* Copyright (C) 2004-2005 Henryk Ploetz <henryk@ploetzli.ch>
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* Copyright (C) 2005-2008 Brad Midgley <bmidgley@xmission.com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* SBC common functions for the encoder and decoder
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*/
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#include "avcodec.h"
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#include "sbc.h"
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/* A2DP specification: Appendix B, page 69 */
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static const int sbc_offset4[4][4] = {
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{ -1, 0, 0, 0 },
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{ -2, 0, 0, 1 },
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{ -2, 0, 0, 1 },
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{ -2, 0, 0, 1 }
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};
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/* A2DP specification: Appendix B, page 69 */
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static const int sbc_offset8[4][8] = {
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{ -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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* Calculates the CRC-8 of the first len bits in data
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*/
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uint8_t ff_sbc_crc8(const AVCRC *ctx, const uint8_t *data, size_t len)
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{
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size_t byte_length = len >> 3;
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int bit_length = len & 7;
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uint8_t crc;
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crc = av_crc(ctx, 0x0F, data, byte_length);
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if (bit_length) {
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uint8_t bits = data[byte_length];
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while (bit_length--) {
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int8_t mask = bits ^ crc;
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crc = (crc << 1) ^ ((mask >> 7) & 0x1D);
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bits <<= 1;
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}
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}
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return crc;
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}
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/*
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* Code straight from the spec to calculate the bits array
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* Takes a pointer to the frame in question and a pointer to the bits array
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*/
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void ff_sbc_calculate_bits(const struct sbc_frame *frame, int (*bits)[8])
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{
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int subbands = frame->subbands;
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uint8_t sf = frame->frequency;
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if (frame->mode == MONO || frame->mode == DUAL_CHANNEL) {
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int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice;
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int ch, sb;
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for (ch = 0; ch < frame->channels; ch++) {
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max_bitneed = 0;
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if (frame->allocation == SNR) {
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for (sb = 0; sb < subbands; sb++) {
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bitneed[ch][sb] = frame->scale_factor[ch][sb];
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if (bitneed[ch][sb] > max_bitneed)
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max_bitneed = bitneed[ch][sb];
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}
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} else {
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for (sb = 0; sb < subbands; sb++) {
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if (frame->scale_factor[ch][sb] == 0)
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bitneed[ch][sb] = -5;
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else {
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if (subbands == 4)
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loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb];
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else
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loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb];
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if (loudness > 0)
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bitneed[ch][sb] = loudness / 2;
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else
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bitneed[ch][sb] = loudness;
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}
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if (bitneed[ch][sb] > max_bitneed)
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max_bitneed = bitneed[ch][sb];
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}
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}
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bitcount = 0;
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slicecount = 0;
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bitslice = max_bitneed + 1;
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do {
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bitslice--;
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bitcount += slicecount;
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slicecount = 0;
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for (sb = 0; sb < subbands; sb++) {
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if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16))
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slicecount++;
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else if (bitneed[ch][sb] == bitslice + 1)
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slicecount += 2;
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}
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} while (bitcount + slicecount < frame->bitpool);
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if (bitcount + slicecount == frame->bitpool) {
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bitcount += slicecount;
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bitslice--;
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}
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for (sb = 0; sb < subbands; sb++) {
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if (bitneed[ch][sb] < bitslice + 2)
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bits[ch][sb] = 0;
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else {
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bits[ch][sb] = bitneed[ch][sb] - bitslice;
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if (bits[ch][sb] > 16)
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bits[ch][sb] = 16;
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}
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}
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for (sb = 0; bitcount < frame->bitpool &&
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sb < subbands; sb++) {
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if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) {
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bits[ch][sb]++;
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bitcount++;
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} else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) {
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bits[ch][sb] = 2;
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bitcount += 2;
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}
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}
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for (sb = 0; bitcount < frame->bitpool &&
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sb < subbands; sb++) {
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if (bits[ch][sb] < 16) {
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bits[ch][sb]++;
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bitcount++;
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}
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}
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}
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} else if (frame->mode == STEREO || frame->mode == JOINT_STEREO) {
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int bitneed[2][8], loudness, max_bitneed, bitcount, slicecount, bitslice;
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int ch, sb;
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max_bitneed = 0;
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if (frame->allocation == SNR) {
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for (ch = 0; ch < 2; ch++) {
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for (sb = 0; sb < subbands; sb++) {
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bitneed[ch][sb] = frame->scale_factor[ch][sb];
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if (bitneed[ch][sb] > max_bitneed)
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max_bitneed = bitneed[ch][sb];
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}
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}
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} else {
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for (ch = 0; ch < 2; ch++) {
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for (sb = 0; sb < subbands; sb++) {
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if (frame->scale_factor[ch][sb] == 0)
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bitneed[ch][sb] = -5;
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else {
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if (subbands == 4)
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loudness = frame->scale_factor[ch][sb] - sbc_offset4[sf][sb];
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else
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loudness = frame->scale_factor[ch][sb] - sbc_offset8[sf][sb];
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if (loudness > 0)
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bitneed[ch][sb] = loudness / 2;
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else
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bitneed[ch][sb] = loudness;
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}
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if (bitneed[ch][sb] > max_bitneed)
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max_bitneed = bitneed[ch][sb];
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}
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}
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}
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bitcount = 0;
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slicecount = 0;
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bitslice = max_bitneed + 1;
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do {
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bitslice--;
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bitcount += slicecount;
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slicecount = 0;
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for (ch = 0; ch < 2; ch++) {
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for (sb = 0; sb < subbands; sb++) {
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if ((bitneed[ch][sb] > bitslice + 1) && (bitneed[ch][sb] < bitslice + 16))
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slicecount++;
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else if (bitneed[ch][sb] == bitslice + 1)
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slicecount += 2;
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}
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}
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} while (bitcount + slicecount < frame->bitpool);
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if (bitcount + slicecount == frame->bitpool) {
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bitcount += slicecount;
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bitslice--;
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}
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for (ch = 0; ch < 2; ch++) {
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for (sb = 0; sb < subbands; sb++) {
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if (bitneed[ch][sb] < bitslice + 2) {
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bits[ch][sb] = 0;
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} else {
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bits[ch][sb] = bitneed[ch][sb] - bitslice;
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if (bits[ch][sb] > 16)
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bits[ch][sb] = 16;
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}
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}
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}
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ch = 0;
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sb = 0;
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while (bitcount < frame->bitpool) {
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if ((bits[ch][sb] >= 2) && (bits[ch][sb] < 16)) {
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bits[ch][sb]++;
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bitcount++;
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} else if ((bitneed[ch][sb] == bitslice + 1) && (frame->bitpool > bitcount + 1)) {
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bits[ch][sb] = 2;
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bitcount += 2;
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}
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if (ch == 1) {
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ch = 0;
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sb++;
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if (sb >= subbands)
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break;
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} else
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ch = 1;
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}
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ch = 0;
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sb = 0;
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while (bitcount < frame->bitpool) {
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if (bits[ch][sb] < 16) {
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bits[ch][sb]++;
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bitcount++;
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}
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if (ch == 1) {
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ch = 0;
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sb++;
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if (sb >= subbands)
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break;
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} else
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ch = 1;
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}
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}
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}
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