/* * G.722 ADPCM audio encoder/decoder * * Copyright (c) CMU 1993 Computer Science, Speech Group * Chengxiang Lu and Alex Hauptmann * Copyright (c) 2005 Steve Underwood <steveu at coppice.org> * Copyright (c) 2009 Kenan Gillet * Copyright (c) 2010 Martin Storsjo * * This file is part of Libav. * * Libav is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * Libav is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * G.722 ADPCM audio codec * * This G.722 decoder is a bit-exact implementation of the ITU G.722 * specification for all three specified bitrates - 64000bps, 56000bps * and 48000bps. It passes the ITU tests. * * @note For the 56000bps and 48000bps bitrates, the lowest 1 or 2 bits * respectively of each byte are ignored. */ #include "mathops.h" #include "g722.h" static const int8_t sign_lookup[2] = { -1, 1 }; static const int16_t inv_log2_table[32] = { 2048, 2093, 2139, 2186, 2233, 2282, 2332, 2383, 2435, 2489, 2543, 2599, 2656, 2714, 2774, 2834, 2896, 2960, 3025, 3091, 3158, 3228, 3298, 3371, 3444, 3520, 3597, 3676, 3756, 3838, 3922, 4008 }; static const int16_t high_log_factor_step[2] = { 798, -214 }; const int16_t ff_g722_high_inv_quant[4] = { -926, -202, 926, 202 }; /** * low_log_factor_step[index] == wl[rl42[index]] */ static const int16_t low_log_factor_step[16] = { -60, 3042, 1198, 538, 334, 172, 58, -30, 3042, 1198, 538, 334, 172, 58, -30, -60 }; const int16_t ff_g722_low_inv_quant4[16] = { 0, -2557, -1612, -1121, -786, -530, -323, -150, 2557, 1612, 1121, 786, 530, 323, 150, 0 }; const int16_t ff_g722_low_inv_quant6[64] = { -17, -17, -17, -17, -3101, -2738, -2376, -2088, -1873, -1689, -1535, -1399, -1279, -1170, -1072, -982, -899, -822, -750, -682, -618, -558, -501, -447, -396, -347, -300, -254, -211, -170, -130, -91, 3101, 2738, 2376, 2088, 1873, 1689, 1535, 1399, 1279, 1170, 1072, 982, 899, 822, 750, 682, 618, 558, 501, 447, 396, 347, 300, 254, 211, 170, 130, 91, 54, 17, -54, -17 }; /** * quadrature mirror filter (QMF) coefficients * * ITU-T G.722 Table 11 */ static const int16_t qmf_coeffs[12] = { 3, -11, 12, 32, -210, 951, 3876, -805, 362, -156, 53, -11, }; /** * adaptive predictor * * @param cur_diff the dequantized and scaled delta calculated from the * current codeword */ static void do_adaptive_prediction(struct G722Band *band, const int cur_diff) { int sg[2], limit, i, cur_qtzd_reconst; const int cur_part_reconst = band->s_zero + cur_diff < 0; sg[0] = sign_lookup[cur_part_reconst != band->part_reconst_mem[0]]; sg[1] = sign_lookup[cur_part_reconst == band->part_reconst_mem[1]]; band->part_reconst_mem[1] = band->part_reconst_mem[0]; band->part_reconst_mem[0] = cur_part_reconst; band->pole_mem[1] = av_clip((sg[0] * av_clip(band->pole_mem[0], -8191, 8191) >> 5) + (sg[1] << 7) + (band->pole_mem[1] * 127 >> 7), -12288, 12288); limit = 15360 - band->pole_mem[1]; band->pole_mem[0] = av_clip(-192 * sg[0] + (band->pole_mem[0] * 255 >> 8), -limit, limit); if (cur_diff) { for (i = 0; i < 6; i++) band->zero_mem[i] = ((band->zero_mem[i]*255) >> 8) + ((band->diff_mem[i]^cur_diff) < 0 ? -128 : 128); } else for (i = 0; i < 6; i++) band->zero_mem[i] = (band->zero_mem[i]*255) >> 8; for (i = 5; i > 0; i--) band->diff_mem[i] = band->diff_mem[i-1]; band->diff_mem[0] = av_clip_int16(cur_diff << 1); band->s_zero = 0; for (i = 5; i >= 0; i--) band->s_zero += (band->zero_mem[i]*band->diff_mem[i]) >> 15; cur_qtzd_reconst = av_clip_int16((band->s_predictor + cur_diff) << 1); band->s_predictor = av_clip_int16(band->s_zero + (band->pole_mem[0] * cur_qtzd_reconst >> 15) + (band->pole_mem[1] * band->prev_qtzd_reconst >> 15)); band->prev_qtzd_reconst = cur_qtzd_reconst; } static inline int linear_scale_factor(const int log_factor) { const int wd1 = inv_log2_table[(log_factor >> 6) & 31]; const int shift = log_factor >> 11; return shift < 0 ? wd1 >> -shift : wd1 << shift; } void ff_g722_update_low_predictor(struct G722Band *band, const int ilow) { do_adaptive_prediction(band, band->scale_factor * ff_g722_low_inv_quant4[ilow] >> 10); // quantizer adaptation band->log_factor = av_clip((band->log_factor * 127 >> 7) + low_log_factor_step[ilow], 0, 18432); band->scale_factor = linear_scale_factor(band->log_factor - (8 << 11)); } void ff_g722_update_high_predictor(struct G722Band *band, const int dhigh, const int ihigh) { do_adaptive_prediction(band, dhigh); // quantizer adaptation band->log_factor = av_clip((band->log_factor * 127 >> 7) + high_log_factor_step[ihigh&1], 0, 22528); band->scale_factor = linear_scale_factor(band->log_factor - (10 << 11)); } void ff_g722_apply_qmf(const int16_t *prev_samples, int *xout1, int *xout2) { int i; *xout1 = 0; *xout2 = 0; for (i = 0; i < 12; i++) { MAC16(*xout2, prev_samples[2*i ], qmf_coeffs[i ]); MAC16(*xout1, prev_samples[2*i+1], qmf_coeffs[11-i]); } }