LCOV - code coverage report
Current view: top level - src/libavcodec - aacenc_tns.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 99 103 96.1 %
Date: 2017-01-28 02:43:52 Functions: 5 5 100.0 %

          Line data    Source code
       1             : /*
       2             :  * AAC encoder TNS
       3             :  * Copyright (C) 2015 Rostislav Pehlivanov
       4             :  *
       5             :  * This file is part of FFmpeg.
       6             :  *
       7             :  * FFmpeg is free software; you can redistribute it and/or
       8             :  * modify it under the terms of the GNU Lesser General Public
       9             :  * License as published by the Free Software Foundation; either
      10             :  * version 2.1 of the License, or (at your option) any later version.
      11             :  *
      12             :  * FFmpeg is distributed in the hope that it will be useful,
      13             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      14             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      15             :  * Lesser General Public License for more details.
      16             :  *
      17             :  * You should have received a copy of the GNU Lesser General Public
      18             :  * License along with FFmpeg; if not, write to the Free Software
      19             :  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
      20             :  */
      21             : 
      22             : /**
      23             :  * @file
      24             :  * AAC encoder temporal noise shaping
      25             :  * @author Rostislav Pehlivanov ( atomnuker gmail com )
      26             :  */
      27             : 
      28             : #include "libavutil/libm.h"
      29             : #include "aacenc.h"
      30             : #include "aacenc_tns.h"
      31             : #include "aactab.h"
      32             : #include "aacenc_utils.h"
      33             : #include "aacenc_quantization.h"
      34             : 
      35             : /* Could be set to 3 to save an additional bit at the cost of little quality */
      36             : #define TNS_Q_BITS 4
      37             : 
      38             : /* Coefficient resolution in short windows */
      39             : #define TNS_Q_BITS_IS8 4
      40             : 
      41             : /* We really need the bits we save here elsewhere */
      42             : #define TNS_ENABLE_COEF_COMPRESSION
      43             : 
      44             : /* TNS will only be used if the LPC gain is within these margins */
      45             : #define TNS_GAIN_THRESHOLD_LOW      1.4f
      46             : #define TNS_GAIN_THRESHOLD_HIGH     1.16f*TNS_GAIN_THRESHOLD_LOW
      47             : 
      48          78 : static inline int compress_coeffs(int *coef, int order, int c_bits)
      49             : {
      50             :     int i;
      51          78 :     const int low_idx   = c_bits ?  4 : 2;
      52          78 :     const int shift_val = c_bits ?  8 : 4;
      53          78 :     const int high_idx  = c_bits ? 11 : 5;
      54             : #ifndef TNS_ENABLE_COEF_COMPRESSION
      55             :     return 0;
      56             : #endif /* TNS_ENABLE_COEF_COMPRESSION */
      57         578 :     for (i = 0; i < order; i++)
      58         500 :         if (coef[i] >= low_idx && coef[i] <= high_idx)
      59           0 :             return 0;
      60         578 :     for (i = 0; i < order; i++)
      61         500 :         coef[i] -= (coef[i] > high_idx) ? shift_val : 0;
      62          78 :     return 1;
      63             : }
      64             : 
      65             : /**
      66             :  * Encode TNS data.
      67             :  * Coefficient compression is simply not lossless as it should be
      68             :  * on any decoder tested and as such is not active.
      69             :  */
      70       12123 : void ff_aac_encode_tns_info(AACEncContext *s, SingleChannelElement *sce)
      71             : {
      72       12123 :     TemporalNoiseShaping *tns = &sce->tns;
      73       12123 :     int i, w, filt, coef_compress = 0, coef_len;
      74       12123 :     const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE;
      75       12123 :     const int c_bits = is8 ? TNS_Q_BITS_IS8 == 4 : TNS_Q_BITS == 4;
      76             : 
      77       12123 :     if (!sce->tns.present)
      78       12083 :         return;
      79             : 
      80         199 :     for (i = 0; i < sce->ics.num_windows; i++) {
      81         159 :         put_bits(&s->pb, 2 - is8, sce->tns.n_filt[i]);
      82         159 :         if (!tns->n_filt[i])
      83         104 :             continue;
      84          55 :         put_bits(&s->pb, 1, c_bits);
      85         133 :         for (filt = 0; filt < tns->n_filt[i]; filt++) {
      86          78 :             put_bits(&s->pb, 6 - 2 * is8, tns->length[i][filt]);
      87          78 :             put_bits(&s->pb, 5 - 2 * is8, tns->order[i][filt]);
      88          78 :             if (!tns->order[i][filt])
      89           0 :                 continue;
      90          78 :             put_bits(&s->pb, 1, tns->direction[i][filt]);
      91          78 :             coef_compress = compress_coeffs(tns->coef_idx[i][filt],
      92             :                                             tns->order[i][filt], c_bits);
      93          78 :             put_bits(&s->pb, 1, coef_compress);
      94          78 :             coef_len = c_bits + 3 - coef_compress;
      95         578 :             for (w = 0; w < tns->order[i][filt]; w++)
      96         500 :                 put_bits(&s->pb, coef_len, tns->coef_idx[i][filt][w]);
      97             :         }
      98             :     }
      99             : }
     100             : 
     101             : /* Apply TNS filter */
     102        1865 : void ff_aac_apply_tns(AACEncContext *s, SingleChannelElement *sce)
     103             : {
     104        1865 :     TemporalNoiseShaping *tns = &sce->tns;
     105        1865 :     IndividualChannelStream *ics = &sce->ics;
     106             :     int w, filt, m, i, top, order, bottom, start, end, size, inc;
     107        1865 :     const int mmm = FFMIN(ics->tns_max_bands, ics->max_sfb);
     108             :     float lpc[TNS_MAX_ORDER];
     109             : 
     110        4038 :     for (w = 0; w < ics->num_windows; w++) {
     111        2173 :         bottom = ics->num_swb;
     112        2251 :         for (filt = 0; filt < tns->n_filt[w]; filt++) {
     113          78 :             top    = bottom;
     114          78 :             bottom = FFMAX(0, top - tns->length[w][filt]);
     115          78 :             order  = tns->order[w][filt];
     116          78 :             if (order == 0)
     117           0 :                 continue;
     118             : 
     119             :             // tns_decode_coef
     120          78 :             compute_lpc_coefs(tns->coef[w][filt], order, lpc, 0, 0, 0);
     121             : 
     122          78 :             start = ics->swb_offset[FFMIN(bottom, mmm)];
     123          78 :             end   = ics->swb_offset[FFMIN(   top, mmm)];
     124          78 :             if ((size = end - start) <= 0)
     125           0 :                 continue;
     126          78 :             if (tns->direction[w][filt]) {
     127          29 :                 inc = -1;
     128          29 :                 start = end - 1;
     129             :             } else {
     130          49 :                 inc = 1;
     131             :             }
     132          78 :             start += w * 128;
     133             : 
     134             :             /* AR filter */
     135       15366 :             for (m = 0; m < size; m++, start += inc) {
     136      108546 :                 for (i = 1; i <= FFMIN(m, order); i++) {
     137       93258 :                     sce->coeffs[start] += lpc[i-1]*sce->pcoeffs[start - i*inc];
     138             :                 }
     139             :             }
     140             :         }
     141             :     }
     142        1865 : }
     143             : 
     144             : /*
     145             :  * c_bits - 1 if 4 bit coefficients, 0 if 3 bit coefficients
     146             :  */
     147          78 : static inline void quantize_coefs(double *coef, int *idx, float *lpc, int order,
     148             :                                   int c_bits)
     149             : {
     150             :     int i;
     151          78 :     const float *quant_arr = tns_tmp2_map[c_bits];
     152         578 :     for (i = 0; i < order; i++) {
     153         500 :         idx[i] = quant_array_idx(coef[i], quant_arr, c_bits ? 16 : 8);
     154         500 :         lpc[i] = quant_arr[idx[i]];
     155             :     }
     156          78 : }
     157             : 
     158             : /*
     159             :  * 3 bits per coefficient with 8 short windows
     160             :  */
     161        1865 : void ff_aac_search_for_tns(AACEncContext *s, SingleChannelElement *sce)
     162             : {
     163        1865 :     TemporalNoiseShaping *tns = &sce->tns;
     164        1865 :     int w, g, count = 0;
     165             :     double gain, coefs[MAX_LPC_ORDER];
     166        1865 :     const int mmm = FFMIN(sce->ics.tns_max_bands, sce->ics.max_sfb);
     167        1865 :     const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE;
     168        1865 :     const int c_bits = is8 ? TNS_Q_BITS_IS8 == 4 : TNS_Q_BITS == 4;
     169        1865 :     const int sfb_start = av_clip(tns_min_sfb[is8][s->samplerate_index], 0, mmm);
     170        1865 :     const int sfb_end   = av_clip(sce->ics.num_swb, 0, mmm);
     171        1865 :     const int order = is8 ? 7 : s->profile == FF_PROFILE_AAC_LOW ? 12 : TNS_MAX_ORDER;
     172        3713 :     const int slant = sce->ics.window_sequence[0] == LONG_STOP_SEQUENCE  ? 1 :
     173        1848 :                       sce->ics.window_sequence[0] == LONG_START_SEQUENCE ? 0 : 2;
     174        1865 :     const int sfb_len = sfb_end - sfb_start;
     175        1865 :     const int coef_len = sce->ics.swb_offset[sfb_end] - sce->ics.swb_offset[sfb_start];
     176             : 
     177        1865 :     if (coef_len <= 0 || sfb_len <= 0) {
     178          87 :         sce->tns.present = 0;
     179          87 :         return;
     180             :     }
     181             : 
     182        3787 :     for (w = 0; w < sce->ics.num_windows; w++) {
     183        2009 :         float en[2] = {0.0f, 0.0f};
     184        2009 :         int oc_start = 0, os_start = 0;
     185        2009 :         int coef_start = sce->ics.swb_offset[sfb_start];
     186             : 
     187       49992 :         for (g = sfb_start; g < sce->ics.num_swb && g <= sfb_end; g++) {
     188       47983 :             FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[w*16+g];
     189       47983 :             if (g > sfb_start + (sfb_len/2))
     190       23770 :                 en[1] += band->energy;
     191             :             else
     192       24213 :                 en[0] += band->energy;
     193             :         }
     194             : 
     195             :         /* LPC */
     196        2009 :         gain = ff_lpc_calc_ref_coefs_f(&s->lpc, &sce->coeffs[w*128 + coef_start],
     197             :                                        coef_len, order, coefs);
     198             : 
     199        2009 :         if (!order || !isfinite(gain) || gain < TNS_GAIN_THRESHOLD_LOW || gain > TNS_GAIN_THRESHOLD_HIGH)
     200        1954 :             continue;
     201             : 
     202          55 :         tns->n_filt[w] = is8 ? 1 : order != TNS_MAX_ORDER ? 2 : 3;
     203         133 :         for (g = 0; g < tns->n_filt[w]; g++) {
     204          78 :             tns->direction[w][g] = slant != 2 ? slant : en[g] < en[!g];
     205          78 :             tns->order[w][g] = g < tns->n_filt[w] ? order/tns->n_filt[w] : order - oc_start;
     206          78 :             tns->length[w][g] = g < tns->n_filt[w] ? sfb_len/tns->n_filt[w] : sfb_len - os_start;
     207          78 :             quantize_coefs(&coefs[oc_start], tns->coef_idx[w][g], tns->coef[w][g],
     208             :                             tns->order[w][g], c_bits);
     209          78 :             oc_start += tns->order[w][g];
     210          78 :             os_start += tns->length[w][g];
     211             :         }
     212          55 :         count++;
     213             :     }
     214        1778 :     sce->tns.present = !!count;
     215             : }

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