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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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} |