forked from KolibriOS/kolibrios
172 lines
6.0 KiB
C
172 lines
6.0 KiB
C
/*
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* G.722 ADPCM audio encoder/decoder
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*
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* Copyright (c) CMU 1993 Computer Science, Speech Group
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* Chengxiang Lu and Alex Hauptmann
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* Copyright (c) 2005 Steve Underwood <steveu at coppice.org>
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* Copyright (c) 2009 Kenan Gillet
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* Copyright (c) 2010 Martin Storsjo
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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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* G.722 ADPCM audio codec
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*
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* This G.722 decoder is a bit-exact implementation of the ITU G.722
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* specification for all three specified bitrates - 64000bps, 56000bps
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* and 48000bps. It passes the ITU tests.
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*
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* @note For the 56000bps and 48000bps bitrates, the lowest 1 or 2 bits
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* respectively of each byte are ignored.
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*/
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#include "mathops.h"
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#include "g722.h"
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static const int8_t sign_lookup[2] = { -1, 1 };
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static const int16_t inv_log2_table[32] = {
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2048, 2093, 2139, 2186, 2233, 2282, 2332, 2383,
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2435, 2489, 2543, 2599, 2656, 2714, 2774, 2834,
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2896, 2960, 3025, 3091, 3158, 3228, 3298, 3371,
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3444, 3520, 3597, 3676, 3756, 3838, 3922, 4008
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};
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static const int16_t high_log_factor_step[2] = { 798, -214 };
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const int16_t ff_g722_high_inv_quant[4] = { -926, -202, 926, 202 };
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/**
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* low_log_factor_step[index] == wl[rl42[index]]
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*/
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static const int16_t low_log_factor_step[16] = {
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-60, 3042, 1198, 538, 334, 172, 58, -30,
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3042, 1198, 538, 334, 172, 58, -30, -60
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};
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const int16_t ff_g722_low_inv_quant4[16] = {
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0, -2557, -1612, -1121, -786, -530, -323, -150,
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2557, 1612, 1121, 786, 530, 323, 150, 0
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};
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const int16_t ff_g722_low_inv_quant6[64] = {
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-17, -17, -17, -17, -3101, -2738, -2376, -2088,
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-1873, -1689, -1535, -1399, -1279, -1170, -1072, -982,
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-899, -822, -750, -682, -618, -558, -501, -447,
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-396, -347, -300, -254, -211, -170, -130, -91,
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3101, 2738, 2376, 2088, 1873, 1689, 1535, 1399,
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1279, 1170, 1072, 982, 899, 822, 750, 682,
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618, 558, 501, 447, 396, 347, 300, 254,
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211, 170, 130, 91, 54, 17, -54, -17
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};
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/**
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* quadrature mirror filter (QMF) coefficients
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*
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* ITU-T G.722 Table 11
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*/
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static const int16_t qmf_coeffs[12] = {
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3, -11, 12, 32, -210, 951, 3876, -805, 362, -156, 53, -11,
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};
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/**
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* adaptive predictor
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*
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* @param cur_diff the dequantized and scaled delta calculated from the
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* current codeword
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*/
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static void do_adaptive_prediction(struct G722Band *band, const int cur_diff)
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{
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int sg[2], limit, i, cur_qtzd_reconst;
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const int cur_part_reconst = band->s_zero + cur_diff < 0;
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sg[0] = sign_lookup[cur_part_reconst != band->part_reconst_mem[0]];
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sg[1] = sign_lookup[cur_part_reconst == band->part_reconst_mem[1]];
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band->part_reconst_mem[1] = band->part_reconst_mem[0];
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band->part_reconst_mem[0] = cur_part_reconst;
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band->pole_mem[1] = av_clip((sg[0] * av_clip(band->pole_mem[0], -8191, 8191) >> 5) +
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(sg[1] << 7) + (band->pole_mem[1] * 127 >> 7), -12288, 12288);
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limit = 15360 - band->pole_mem[1];
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band->pole_mem[0] = av_clip(-192 * sg[0] + (band->pole_mem[0] * 255 >> 8), -limit, limit);
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if (cur_diff) {
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for (i = 0; i < 6; i++)
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band->zero_mem[i] = ((band->zero_mem[i]*255) >> 8) +
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((band->diff_mem[i]^cur_diff) < 0 ? -128 : 128);
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} else
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for (i = 0; i < 6; i++)
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band->zero_mem[i] = (band->zero_mem[i]*255) >> 8;
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for (i = 5; i > 0; i--)
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band->diff_mem[i] = band->diff_mem[i-1];
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band->diff_mem[0] = av_clip_int16(cur_diff << 1);
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band->s_zero = 0;
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for (i = 5; i >= 0; i--)
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band->s_zero += (band->zero_mem[i]*band->diff_mem[i]) >> 15;
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cur_qtzd_reconst = av_clip_int16((band->s_predictor + cur_diff) << 1);
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band->s_predictor = av_clip_int16(band->s_zero +
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(band->pole_mem[0] * cur_qtzd_reconst >> 15) +
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(band->pole_mem[1] * band->prev_qtzd_reconst >> 15));
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band->prev_qtzd_reconst = cur_qtzd_reconst;
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}
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static inline int linear_scale_factor(const int log_factor)
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{
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const int wd1 = inv_log2_table[(log_factor >> 6) & 31];
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const int shift = log_factor >> 11;
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return shift < 0 ? wd1 >> -shift : wd1 << shift;
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}
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void ff_g722_update_low_predictor(struct G722Band *band, const int ilow)
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{
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do_adaptive_prediction(band,
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band->scale_factor * ff_g722_low_inv_quant4[ilow] >> 10);
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// quantizer adaptation
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band->log_factor = av_clip((band->log_factor * 127 >> 7) +
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low_log_factor_step[ilow], 0, 18432);
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band->scale_factor = linear_scale_factor(band->log_factor - (8 << 11));
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}
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void ff_g722_update_high_predictor(struct G722Band *band, const int dhigh,
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const int ihigh)
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{
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do_adaptive_prediction(band, dhigh);
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// quantizer adaptation
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band->log_factor = av_clip((band->log_factor * 127 >> 7) +
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high_log_factor_step[ihigh&1], 0, 22528);
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band->scale_factor = linear_scale_factor(band->log_factor - (10 << 11));
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}
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void ff_g722_apply_qmf(const int16_t *prev_samples, int *xout1, int *xout2)
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{
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int i;
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*xout1 = 0;
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*xout2 = 0;
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for (i = 0; i < 12; i++) {
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MAC16(*xout2, prev_samples[2*i ], qmf_coeffs[i ]);
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MAC16(*xout1, prev_samples[2*i+1], qmf_coeffs[11-i]);
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}
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}
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