| /* |
| * AAC encoder TNS |
| * Copyright (C) 2015 Rostislav Pehlivanov |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg 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. |
| * |
| * FFmpeg 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 FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| /** |
| * @file |
| * AAC encoder temporal noise shaping |
| * @author Rostislav Pehlivanov ( atomnuker gmail com ) |
| */ |
| |
| #include "aacenc.h" |
| #include "aacenc_tns.h" |
| #include "aactab.h" |
| #include "aacenc_utils.h" |
| #include "aacenc_quantization.h" |
| |
| /** |
| * Encode TNS data. |
| * Coefficient compression saves a single bit per coefficient. |
| */ |
| void ff_aac_encode_tns_info(AACEncContext *s, SingleChannelElement *sce) |
| { |
| uint8_t u_coef; |
| const uint8_t coef_res = TNS_Q_BITS == 4; |
| int i, w, filt, coef_len, coef_compress = 0; |
| const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE; |
| TemporalNoiseShaping *tns = &sce->tns; |
| |
| if (!sce->tns.present) |
| return; |
| |
| for (i = 0; i < sce->ics.num_windows; i++) { |
| put_bits(&s->pb, 2 - is8, sce->tns.n_filt[i]); |
| if (tns->n_filt[i]) { |
| put_bits(&s->pb, 1, coef_res); |
| for (filt = 0; filt < tns->n_filt[i]; filt++) { |
| put_bits(&s->pb, 6 - 2 * is8, tns->length[i][filt]); |
| put_bits(&s->pb, 5 - 2 * is8, tns->order[i][filt]); |
| if (tns->order[i][filt]) { |
| put_bits(&s->pb, 1, !!tns->direction[i][filt]); |
| put_bits(&s->pb, 1, !!coef_compress); |
| coef_len = coef_res + 3 - coef_compress; |
| for (w = 0; w < tns->order[i][filt]; w++) { |
| u_coef = (tns->coef_idx[i][filt][w])&(~(~0<<coef_len)); |
| put_bits(&s->pb, coef_len, u_coef); |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| static inline void quantize_coefs(double *coef, int *idx, float *lpc, int order) |
| { |
| int i; |
| uint8_t u_coef; |
| const float *quant_arr = tns_tmp2_map[TNS_Q_BITS == 4]; |
| const double iqfac_p = ((1 << (TNS_Q_BITS-1)) - 0.5)/(M_PI/2.0); |
| const double iqfac_m = ((1 << (TNS_Q_BITS-1)) + 0.5)/(M_PI/2.0); |
| for (i = 0; i < order; i++) { |
| idx[i] = ceilf(asin(coef[i])*((coef[i] >= 0) ? iqfac_p : iqfac_m)); |
| u_coef = (idx[i])&(~(~0<<TNS_Q_BITS)); |
| lpc[i] = quant_arr[u_coef]; |
| } |
| } |
| |
| /* Apply TNS filter */ |
| void ff_aac_apply_tns(AACEncContext *s, SingleChannelElement *sce) |
| { |
| TemporalNoiseShaping *tns = &sce->tns; |
| IndividualChannelStream *ics = &sce->ics; |
| int w, filt, m, i, top, order, bottom, start, end, size, inc; |
| const int mmm = FFMIN(ics->tns_max_bands, ics->max_sfb); |
| float lpc[TNS_MAX_ORDER]; |
| |
| for (w = 0; w < ics->num_windows; w++) { |
| bottom = ics->num_swb; |
| for (filt = 0; filt < tns->n_filt[w]; filt++) { |
| top = bottom; |
| bottom = FFMAX(0, top - tns->length[w][filt]); |
| order = tns->order[w][filt]; |
| if (order == 0) |
| continue; |
| |
| // tns_decode_coef |
| compute_lpc_coefs(tns->coef[w][filt], order, lpc, 0, 0, 0); |
| |
| start = ics->swb_offset[FFMIN(bottom, mmm)]; |
| end = ics->swb_offset[FFMIN( top, mmm)]; |
| if ((size = end - start) <= 0) |
| continue; |
| if (tns->direction[w][filt]) { |
| inc = -1; |
| start = end - 1; |
| } else { |
| inc = 1; |
| } |
| start += w * 128; |
| |
| // ar filter |
| for (m = 0; m < size; m++, start += inc) |
| for (i = 1; i <= FFMIN(m, order); i++) |
| sce->coeffs[start] += lpc[i-1]*sce->pcoeffs[start - i*inc]; |
| } |
| } |
| } |
| |
| void ff_aac_search_for_tns(AACEncContext *s, SingleChannelElement *sce) |
| { |
| TemporalNoiseShaping *tns = &sce->tns; |
| int w, w2, g, count = 0; |
| const int mmm = FFMIN(sce->ics.tns_max_bands, sce->ics.max_sfb); |
| const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE; |
| const int order = is8 ? 7 : s->profile == FF_PROFILE_AAC_LOW ? 12 : TNS_MAX_ORDER; |
| |
| int sfb_start = av_clip(tns_min_sfb[is8][s->samplerate_index], 0, mmm); |
| int sfb_end = av_clip(sce->ics.num_swb, 0, mmm); |
| |
| for (w = 0; w < sce->ics.num_windows; w++) { |
| float e_ratio = 0.0f, threshold = 0.0f, spread = 0.0f, en[2] = {0.0, 0.0f}; |
| double gain = 0.0f, coefs[MAX_LPC_ORDER] = {0}; |
| int coef_start = w*sce->ics.num_swb + sce->ics.swb_offset[sfb_start]; |
| int coef_len = sce->ics.swb_offset[sfb_end] - sce->ics.swb_offset[sfb_start]; |
| |
| for (g = 0; g < sce->ics.num_swb; g++) { |
| if (w*16+g < sfb_start || w*16+g > sfb_end) |
| continue; |
| for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) { |
| FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g]; |
| if ((w+w2)*16+g > sfb_start + ((sfb_end - sfb_start)/2)) |
| en[1] += band->energy; |
| else |
| en[0] += band->energy; |
| threshold += band->threshold; |
| spread += band->spread; |
| } |
| } |
| |
| if (coef_len <= 0 || (sfb_end - sfb_start) <= 0) |
| continue; |
| else |
| e_ratio = en[0]/en[1]; |
| |
| /* LPC */ |
| gain = ff_lpc_calc_ref_coefs_f(&s->lpc, &sce->coeffs[coef_start], |
| coef_len, order, coefs); |
| |
| if (gain > TNS_GAIN_THRESHOLD_LOW && gain < TNS_GAIN_THRESHOLD_HIGH && |
| (en[0]+en[1]) > TNS_GAIN_THRESHOLD_LOW*threshold && |
| spread < TNS_SPREAD_THRESHOLD && order) { |
| if (is8 || order < 2 || (e_ratio > TNS_E_RATIO_LOW && e_ratio < TNS_E_RATIO_HIGH)) { |
| tns->n_filt[w] = 1; |
| for (g = 0; g < tns->n_filt[w]; g++) { |
| tns->length[w][g] = sfb_end - sfb_start; |
| tns->direction[w][g] = en[0] < en[1]; |
| tns->order[w][g] = order; |
| quantize_coefs(coefs, tns->coef_idx[w][g], tns->coef[w][g], |
| order); |
| } |
| } else { /* 2 filters due to energy disbalance */ |
| tns->n_filt[w] = 2; |
| for (g = 0; g < tns->n_filt[w]; g++) { |
| tns->direction[w][g] = en[g] < en[!g]; |
| tns->order[w][g] = !g ? order/2 : order - tns->order[w][g-1]; |
| tns->length[w][g] = !g ? (sfb_end - sfb_start)/2 : \ |
| (sfb_end - sfb_start) - tns->length[w][g-1]; |
| quantize_coefs(&coefs[!g ? 0 : order - tns->order[w][g-1]], |
| tns->coef_idx[w][g], tns->coef[w][g], |
| tns->order[w][g]); |
| } |
| } |
| count++; |
| } |
| } |
| |
| sce->tns.present = !!count; |
| } |