diff options
Diffstat (limited to 'libavcodec/aacenc_tns.c')
| -rw-r--r-- | libavcodec/aacenc_tns.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/libavcodec/aacenc_tns.c b/libavcodec/aacenc_tns.c new file mode 100644 index 0000000000..637b81385e --- /dev/null +++ b/libavcodec/aacenc_tns.c @@ -0,0 +1,194 @@ +/* + * 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; +} |