yading@10: /*
yading@10:  * Common code between the AC-3 encoder and decoder
yading@10:  * Copyright (c) 2000 Fabrice Bellard
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * Common code between the AC-3 encoder and decoder.
yading@10:  */
yading@10: 
yading@10: #include "avcodec.h"
yading@10: #include "ac3.h"
yading@10: #include "get_bits.h"
yading@10: 
yading@10: /**
yading@10:  * Starting frequency coefficient bin for each critical band.
yading@10:  */
yading@10: const uint8_t ff_ac3_band_start_tab[AC3_CRITICAL_BANDS+1] = {
yading@10:       0,  1,   2,   3,   4,   5,   6,   7,   8,   9,
yading@10:      10,  11, 12,  13,  14,  15,  16,  17,  18,  19,
yading@10:      20,  21, 22,  23,  24,  25,  26,  27,  28,  31,
yading@10:      34,  37, 40,  43,  46,  49,  55,  61,  67,  73,
yading@10:      79,  85, 97, 109, 121, 133, 157, 181, 205, 229, 253
yading@10: };
yading@10: 
yading@10: #if CONFIG_HARDCODED_TABLES
yading@10: 
yading@10: /**
yading@10:  * Map each frequency coefficient bin to the critical band that contains it.
yading@10:  */
yading@10: const uint8_t ff_ac3_bin_to_band_tab[253] = {
yading@10:      0,
yading@10:      1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12,
yading@10:     13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
yading@10:     25, 26, 27, 28, 28, 28, 29, 29, 29, 30, 30, 30,
yading@10:     31, 31, 31, 32, 32, 32, 33, 33, 33, 34, 34, 34,
yading@10:     35, 35, 35, 35, 35, 35, 36, 36, 36, 36, 36, 36,
yading@10:     37, 37, 37, 37, 37, 37, 38, 38, 38, 38, 38, 38,
yading@10:     39, 39, 39, 39, 39, 39, 40, 40, 40, 40, 40, 40,
yading@10:     41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41,
yading@10:     42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42,
yading@10:     43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43,
yading@10:     44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44,
yading@10:     45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45,
yading@10:     45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45,
yading@10:     46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46,
yading@10:     46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46,
yading@10:     47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47,
yading@10:     47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47,
yading@10:     48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
yading@10:     48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48,
yading@10:     49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49,
yading@10:     49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49
yading@10: };
yading@10: 
yading@10: #else /* CONFIG_HARDCODED_TABLES */
yading@10: uint8_t ff_ac3_bin_to_band_tab[253];
yading@10: #endif
yading@10: 
yading@10: static inline int calc_lowcomp1(int a, int b0, int b1, int c)
yading@10: {
yading@10:     if ((b0 + 256) == b1) {
yading@10:         a = c;
yading@10:     } else if (b0 > b1) {
yading@10:         a = FFMAX(a - 64, 0);
yading@10:     }
yading@10:     return a;
yading@10: }
yading@10: 
yading@10: static inline int calc_lowcomp(int a, int b0, int b1, int bin)
yading@10: {
yading@10:     if (bin < 7) {
yading@10:         return calc_lowcomp1(a, b0, b1, 384);
yading@10:     } else if (bin < 20) {
yading@10:         return calc_lowcomp1(a, b0, b1, 320);
yading@10:     } else {
yading@10:         return FFMAX(a - 128, 0);
yading@10:     }
yading@10: }
yading@10: 
yading@10: void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd,
yading@10:                                int16_t *band_psd)
yading@10: {
yading@10:     int bin, band;
yading@10: 
yading@10:     /* exponent mapping to PSD */
yading@10:     for (bin = start; bin < end; bin++) {
yading@10:         psd[bin]=(3072 - (exp[bin] << 7));
yading@10:     }
yading@10: 
yading@10:     /* PSD integration */
yading@10:     bin  = start;
yading@10:     band = ff_ac3_bin_to_band_tab[start];
yading@10:     do {
yading@10:         int v = psd[bin++];
yading@10:         int band_end = FFMIN(ff_ac3_band_start_tab[band+1], end);
yading@10:         for (; bin < band_end; bin++) {
yading@10:             int max = FFMAX(v, psd[bin]);
yading@10:             /* logadd */
yading@10:             int adr = FFMIN(max - ((v + psd[bin] + 1) >> 1), 255);
yading@10:             v = max + ff_ac3_log_add_tab[adr];
yading@10:         }
yading@10:         band_psd[band++] = v;
yading@10:     } while (end > ff_ac3_band_start_tab[band]);
yading@10: }
yading@10: 
yading@10: int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd,
yading@10:                                int start, int end, int fast_gain, int is_lfe,
yading@10:                                int dba_mode, int dba_nsegs, uint8_t *dba_offsets,
yading@10:                                uint8_t *dba_lengths, uint8_t *dba_values,
yading@10:                                int16_t *mask)
yading@10: {
yading@10:     int16_t excite[AC3_CRITICAL_BANDS]; /* excitation */
yading@10:     int band;
yading@10:     int band_start, band_end, begin, end1;
yading@10:     int lowcomp, fastleak, slowleak;
yading@10: 
yading@10:     /* excitation function */
yading@10:     band_start = ff_ac3_bin_to_band_tab[start];
yading@10:     band_end   = ff_ac3_bin_to_band_tab[end-1] + 1;
yading@10: 
yading@10:     if (band_start == 0) {
yading@10:         lowcomp = 0;
yading@10:         lowcomp = calc_lowcomp1(lowcomp, band_psd[0], band_psd[1], 384);
yading@10:         excite[0] = band_psd[0] - fast_gain - lowcomp;
yading@10:         lowcomp = calc_lowcomp1(lowcomp, band_psd[1], band_psd[2], 384);
yading@10:         excite[1] = band_psd[1] - fast_gain - lowcomp;
yading@10:         begin = 7;
yading@10:         for (band = 2; band < 7; band++) {
yading@10:             if (!(is_lfe && band == 6))
yading@10:                 lowcomp = calc_lowcomp1(lowcomp, band_psd[band], band_psd[band+1], 384);
yading@10:             fastleak = band_psd[band] - fast_gain;
yading@10:             slowleak = band_psd[band] - s->slow_gain;
yading@10:             excite[band] = fastleak - lowcomp;
yading@10:             if (!(is_lfe && band == 6)) {
yading@10:                 if (band_psd[band] <= band_psd[band+1]) {
yading@10:                     begin = band + 1;
yading@10:                     break;
yading@10:                 }
yading@10:             }
yading@10:         }
yading@10: 
yading@10:         end1 = FFMIN(band_end, 22);
yading@10:         for (band = begin; band < end1; band++) {
yading@10:             if (!(is_lfe && band == 6))
yading@10:                 lowcomp = calc_lowcomp(lowcomp, band_psd[band], band_psd[band+1], band);
yading@10:             fastleak = FFMAX(fastleak - s->fast_decay, band_psd[band] - fast_gain);
yading@10:             slowleak = FFMAX(slowleak - s->slow_decay, band_psd[band] - s->slow_gain);
yading@10:             excite[band] = FFMAX(fastleak - lowcomp, slowleak);
yading@10:         }
yading@10:         begin = 22;
yading@10:     } else {
yading@10:         /* coupling channel */
yading@10:         begin = band_start;
yading@10:         fastleak = (s->cpl_fast_leak << 8) + 768;
yading@10:         slowleak = (s->cpl_slow_leak << 8) + 768;
yading@10:     }
yading@10: 
yading@10:     for (band = begin; band < band_end; band++) {
yading@10:         fastleak = FFMAX(fastleak - s->fast_decay, band_psd[band] - fast_gain);
yading@10:         slowleak = FFMAX(slowleak - s->slow_decay, band_psd[band] - s->slow_gain);
yading@10:         excite[band] = FFMAX(fastleak, slowleak);
yading@10:     }
yading@10: 
yading@10:     /* compute masking curve */
yading@10: 
yading@10:     for (band = band_start; band < band_end; band++) {
yading@10:         int tmp = s->db_per_bit - band_psd[band];
yading@10:         if (tmp > 0) {
yading@10:             excite[band] += tmp >> 2;
yading@10:         }
yading@10:         mask[band] = FFMAX(ff_ac3_hearing_threshold_tab[band >> s->sr_shift][s->sr_code], excite[band]);
yading@10:     }
yading@10: 
yading@10:     /* delta bit allocation */
yading@10: 
yading@10:     if (dba_mode == DBA_REUSE || dba_mode == DBA_NEW) {
yading@10:         int i, seg, delta;
yading@10:         if (dba_nsegs > 8)
yading@10:             return -1;
yading@10:         band = band_start;
yading@10:         for (seg = 0; seg < dba_nsegs; seg++) {
yading@10:             band += dba_offsets[seg];
yading@10:             if (band >= AC3_CRITICAL_BANDS || dba_lengths[seg] > AC3_CRITICAL_BANDS-band)
yading@10:                 return -1;
yading@10:             if (dba_values[seg] >= 4) {
yading@10:                 delta = (dba_values[seg] - 3) << 7;
yading@10:             } else {
yading@10:                 delta = (dba_values[seg] - 4) << 7;
yading@10:             }
yading@10:             for (i = 0; i < dba_lengths[seg]; i++) {
yading@10:                 mask[band++] += delta;
yading@10:             }
yading@10:         }
yading@10:     }
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: /**
yading@10:  * Initialize some tables.
yading@10:  * note: This function must remain thread safe because it is called by the
yading@10:  *       AVParser init code.
yading@10:  */
yading@10: av_cold void ff_ac3_common_init(void)
yading@10: {
yading@10: #if !CONFIG_HARDCODED_TABLES
yading@10:     /* compute ff_ac3_bin_to_band_tab from ff_ac3_band_start_tab */
yading@10:     int bin = 0, band;
yading@10:     for (band = 0; band < AC3_CRITICAL_BANDS; band++) {
yading@10:         int band_end = ff_ac3_band_start_tab[band+1];
yading@10:         while (bin < band_end)
yading@10:             ff_ac3_bin_to_band_tab[bin++] = band;
yading@10:     }
yading@10: #endif /* !CONFIG_HARDCODED_TABLES */
yading@10: }