LCOV - code coverage report
Current view: top level - libavcodec - lpc.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 137 150 91.3 %
Date: 2017-12-13 10:57:33 Functions: 8 9 88.9 %

          Line data    Source code
       1             : /*
       2             :  * LPC utility code
       3             :  * Copyright (c) 2006  Justin Ruggles <justin.ruggles@gmail.com>
       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             : #include "libavutil/common.h"
      23             : #include "libavutil/lls.h"
      24             : 
      25             : #define LPC_USE_DOUBLE
      26             : #include "lpc.h"
      27             : #include "libavutil/avassert.h"
      28             : 
      29             : 
      30             : /**
      31             :  * Apply Welch window function to audio block
      32             :  */
      33        3969 : static void lpc_apply_welch_window_c(const int32_t *data, int len,
      34             :                                      double *w_data)
      35             : {
      36             :     int i, n2;
      37             :     double w;
      38             :     double c;
      39             : 
      40        3969 :     n2 = (len >> 1);
      41        3969 :     c = 2.0 / (len - 1.0);
      42             : 
      43        3969 :     if (len & 1) {
      44        1050 :         for(i=0; i<n2; i++) {
      45        1048 :             w = c - i - 1.0;
      46        1048 :             w = 1.0 - (w * w);
      47        1048 :             w_data[i] = data[i] * w;
      48        1048 :             w_data[len-1-i] = data[len-1-i] * w;
      49             :         }
      50           2 :         return;
      51             :     }
      52             : 
      53        3967 :     w_data+=n2;
      54        3967 :       data+=n2;
      55     9253857 :     for(i=0; i<n2; i++) {
      56     9249890 :         w = c - n2 + i;
      57     9249890 :         w = 1.0 - (w * w);
      58     9249890 :         w_data[-i-1] = data[-i-1] * w;
      59     9249890 :         w_data[+i  ] = data[+i  ] * w;
      60             :     }
      61             : }
      62             : 
      63             : /**
      64             :  * Calculate autocorrelation data from audio samples
      65             :  * A Welch window function is applied before calculation.
      66             :  */
      67        5978 : static void lpc_compute_autocorr_c(const double *data, int len, int lag,
      68             :                                    double *autoc)
      69             : {
      70             :     int i, j;
      71             : 
      72       45593 :     for(j=0; j<lag; j+=2){
      73       39615 :         double sum0 = 1.0, sum1 = 1.0;
      74   134961493 :         for(i=j; i<len; i++){
      75   134921878 :             sum0 += data[i] * data[i-j];
      76   134921878 :             sum1 += data[i] * data[i-j-1];
      77             :         }
      78       39615 :         autoc[j  ] = sum0;
      79       39615 :         autoc[j+1] = sum1;
      80             :     }
      81             : 
      82        5978 :     if(j==lag){
      83        5714 :         double sum = 1.0;
      84     9775627 :         for(i=j-1; i<len; i+=2){
      85    19539826 :             sum += data[i  ] * data[i-j  ]
      86     9769913 :                  + data[i+1] * data[i-j+1];
      87             :         }
      88        5714 :         autoc[j] = sum;
      89             :     }
      90        5978 : }
      91             : 
      92             : /**
      93             :  * Quantize LPC coefficients
      94             :  */
      95       11765 : static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
      96             :                                int32_t *lpc_out, int *shift, int min_shift,
      97             :                                int max_shift, int zero_shift)
      98             : {
      99             :     int i;
     100             :     double cmax, error;
     101             :     int32_t qmax;
     102             :     int sh;
     103             : 
     104             :     /* define maximum levels */
     105       11765 :     qmax = (1 << (precision - 1)) - 1;
     106             : 
     107             :     /* find maximum coefficient value */
     108       11765 :     cmax = 0.0;
     109       69630 :     for(i=0; i<order; i++) {
     110       57865 :         cmax= FFMAX(cmax, fabs(lpc_in[i]));
     111             :     }
     112             : 
     113             :     /* if maximum value quantizes to zero, return all zeros */
     114       11765 :     if(cmax * (1 << max_shift) < 1.0) {
     115           0 :         *shift = zero_shift;
     116           0 :         memset(lpc_out, 0, sizeof(int32_t) * order);
     117           0 :         return;
     118             :     }
     119             : 
     120             :     /* calculate level shift which scales max coeff to available bits */
     121       11765 :     sh = max_shift;
     122       44004 :     while((cmax * (1 << sh) > qmax) && (sh > min_shift)) {
     123       20474 :         sh--;
     124             :     }
     125             : 
     126             :     /* since negative shift values are unsupported in decoder, scale down
     127             :        coefficients instead */
     128       11765 :     if(sh == 0 && cmax > qmax) {
     129           0 :         double scale = ((double)qmax) / cmax;
     130           0 :         for(i=0; i<order; i++) {
     131           0 :             lpc_in[i] *= scale;
     132             :         }
     133             :     }
     134             : 
     135             :     /* output quantized coefficients and level shift */
     136       11765 :     error=0;
     137       69630 :     for(i=0; i<order; i++) {
     138       57865 :         error -= lpc_in[i] * (1 << sh);
     139       57865 :         lpc_out[i] = av_clip(lrintf(error), -qmax, qmax);
     140       57865 :         error -= lpc_out[i];
     141             :     }
     142       11765 :     *shift = sh;
     143             : }
     144             : 
     145        8933 : static int estimate_best_order(double *ref, int min_order, int max_order)
     146             : {
     147             :     int i, est;
     148             : 
     149        8933 :     est = min_order;
     150       64596 :     for(i=max_order-1; i>=min_order-1; i--) {
     151       64422 :         if(ref[i] > 0.10) {
     152        8759 :             est = i+1;
     153        8759 :             break;
     154             :         }
     155             :     }
     156        8933 :     return est;
     157             : }
     158             : 
     159           0 : int ff_lpc_calc_ref_coefs(LPCContext *s,
     160             :                           const int32_t *samples, int order, double *ref)
     161             : {
     162             :     double autoc[MAX_LPC_ORDER + 1];
     163             : 
     164           0 :     s->lpc_apply_welch_window(samples, s->blocksize, s->windowed_samples);
     165           0 :     s->lpc_compute_autocorr(s->windowed_samples, s->blocksize, order, autoc);
     166           0 :     compute_ref_coefs(autoc, order, ref, NULL);
     167             : 
     168           0 :     return order;
     169             : }
     170             : 
     171        2009 : double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len,
     172             :                                int order, double *ref)
     173             : {
     174             :     int i;
     175        2009 :     double signal = 0.0f, avg_err = 0.0f;
     176        2009 :     double autoc[MAX_LPC_ORDER+1] = {0}, error[MAX_LPC_ORDER+1] = {0};
     177        2009 :     const double a = 0.5f, b = 1.0f - a;
     178             : 
     179             :     /* Apply windowing */
     180      570190 :     for (i = 0; i <= len / 2; i++) {
     181      568181 :         double weight = a - b*cos((2*M_PI*i)/(len - 1));
     182      568181 :         s->windowed_samples[i] = weight*samples[i];
     183      568181 :         s->windowed_samples[len-1-i] = weight*samples[len-1-i];
     184             :     }
     185             : 
     186        2009 :     s->lpc_compute_autocorr(s->windowed_samples, len, order, autoc);
     187        2009 :     signal = autoc[0];
     188        2009 :     compute_ref_coefs(autoc, order, ref, error);
     189       24797 :     for (i = 0; i < order; i++)
     190       22788 :         avg_err = (avg_err + error[i])/2.0f;
     191        2009 :     return signal/avg_err;
     192             : }
     193             : 
     194             : /**
     195             :  * Calculate LPC coefficients for multiple orders
     196             :  *
     197             :  * @param lpc_type LPC method for determining coefficients,
     198             :  *                 see #FFLPCType for details
     199             :  */
     200        9169 : int ff_lpc_calc_coefs(LPCContext *s,
     201             :                       const int32_t *samples, int blocksize, int min_order,
     202             :                       int max_order, int precision,
     203             :                       int32_t coefs[][MAX_LPC_ORDER], int *shift,
     204             :                       enum FFLPCType lpc_type, int lpc_passes,
     205             :                       int omethod, int min_shift, int max_shift, int zero_shift)
     206             : {
     207             :     double autoc[MAX_LPC_ORDER+1];
     208        9169 :     double ref[MAX_LPC_ORDER] = { 0 };
     209             :     double lpc[MAX_LPC_ORDER][MAX_LPC_ORDER];
     210        9169 :     int i, j, pass = 0;
     211             :     int opt_order;
     212             : 
     213             :     av_assert2(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER &&
     214             :            lpc_type > FF_LPC_TYPE_FIXED);
     215        9169 :     av_assert0(lpc_type == FF_LPC_TYPE_CHOLESKY || lpc_type == FF_LPC_TYPE_LEVINSON);
     216             : 
     217             :     /* reinit LPC context if parameters have changed */
     218       18325 :     if (blocksize != s->blocksize || max_order != s->max_order ||
     219        9156 :         lpc_type  != s->lpc_type) {
     220          14 :         ff_lpc_end(s);
     221          14 :         ff_lpc_init(s, blocksize, max_order, lpc_type);
     222             :     }
     223             : 
     224        9169 :     if(lpc_passes <= 0)
     225        2589 :         lpc_passes = 2;
     226             : 
     227        9169 :     if (lpc_type == FF_LPC_TYPE_LEVINSON || (lpc_type == FF_LPC_TYPE_CHOLESKY && lpc_passes > 1)) {
     228        9169 :         s->lpc_apply_welch_window(samples, blocksize, s->windowed_samples);
     229             : 
     230        9169 :         s->lpc_compute_autocorr(s->windowed_samples, blocksize, max_order, autoc);
     231             : 
     232        9169 :         compute_lpc_coefs(autoc, max_order, &lpc[0][0], MAX_LPC_ORDER, 0, 1);
     233             : 
     234      106947 :         for(i=0; i<max_order; i++)
     235       97778 :             ref[i] = fabs(lpc[i][i]);
     236             : 
     237        9169 :         pass++;
     238             :     }
     239             : 
     240        9169 :     if (lpc_type == FF_LPC_TYPE_CHOLESKY) {
     241         182 :         LLSModel *m = s->lls_models;
     242         182 :         LOCAL_ALIGNED(32, double, var, [FFALIGN(MAX_LPC_ORDER+1,4)]);
     243         182 :         double av_uninit(weight);
     244         182 :         memset(var, 0, FFALIGN(MAX_LPC_ORDER+1,4)*sizeof(*var));
     245             : 
     246        1638 :         for(j=0; j<max_order; j++)
     247        1456 :             m[0].coeff[max_order-1][j] = -lpc[max_order-1][j];
     248             : 
     249         364 :         for(; pass<lpc_passes; pass++){
     250         182 :             avpriv_init_lls(&m[pass&1], max_order);
     251             : 
     252         182 :             weight=0;
     253      836626 :             for(i=max_order; i<blocksize; i++){
     254     8364440 :                 for(j=0; j<=max_order; j++)
     255     7527996 :                     var[j]= samples[i-j];
     256             : 
     257      836444 :                 if(pass){
     258             :                     double eval, inv, rinv;
     259      836444 :                     eval= m[pass&1].evaluate_lls(&m[(pass-1)&1], var+1, max_order-1);
     260      836444 :                     eval= (512>>pass) + fabs(eval - var[0]);
     261      836444 :                     inv = 1/eval;
     262      836444 :                     rinv = sqrt(inv);
     263     8364440 :                     for(j=0; j<=max_order; j++)
     264     7527996 :                         var[j] *= rinv;
     265      836444 :                     weight += inv;
     266             :                 }else
     267           0 :                     weight++;
     268             : 
     269      836444 :                 m[pass&1].update_lls(&m[pass&1], var);
     270             :             }
     271         182 :             avpriv_solve_lls(&m[pass&1], 0.001, 0);
     272             :         }
     273             : 
     274        1638 :         for(i=0; i<max_order; i++){
     275       13104 :             for(j=0; j<max_order; j++)
     276       11648 :                 lpc[i][j]=-m[(pass-1)&1].coeff[i][j];
     277        1456 :             ref[i]= sqrt(m[(pass-1)&1].variance[i] / weight) * (blocksize - max_order) / 4000;
     278             :         }
     279        1456 :         for(i=max_order-1; i>0; i--)
     280        1274 :             ref[i] = ref[i-1] - ref[i];
     281             :     }
     282             : 
     283        9169 :     opt_order = max_order;
     284             : 
     285        9169 :     if(omethod == ORDER_METHOD_EST) {
     286        8933 :         opt_order = estimate_best_order(ref, min_order, max_order);
     287        8933 :         i = opt_order-1;
     288        8933 :         quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i],
     289             :                            min_shift, max_shift, zero_shift);
     290             :     } else {
     291        3068 :         for(i=min_order-1; i<max_order; i++) {
     292        2832 :             quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i],
     293             :                                min_shift, max_shift, zero_shift);
     294             :         }
     295             :     }
     296             : 
     297        9169 :     return opt_order;
     298             : }
     299             : 
     300          64 : av_cold int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
     301             :                         enum FFLPCType lpc_type)
     302             : {
     303          64 :     s->blocksize = blocksize;
     304          64 :     s->max_order = max_order;
     305          64 :     s->lpc_type  = lpc_type;
     306             : 
     307          64 :     s->windowed_buffer = av_mallocz((blocksize + 2 + FFALIGN(max_order, 4)) *
     308             :                                     sizeof(*s->windowed_samples));
     309          64 :     if (!s->windowed_buffer)
     310           0 :         return AVERROR(ENOMEM);
     311          64 :     s->windowed_samples = s->windowed_buffer + FFALIGN(max_order, 4);
     312             : 
     313          64 :     s->lpc_apply_welch_window = lpc_apply_welch_window_c;
     314          64 :     s->lpc_compute_autocorr   = lpc_compute_autocorr_c;
     315             : 
     316             :     if (ARCH_X86)
     317          64 :         ff_lpc_init_x86(s);
     318             : 
     319          64 :     return 0;
     320             : }
     321             : 
     322          64 : av_cold void ff_lpc_end(LPCContext *s)
     323             : {
     324          64 :     av_freep(&s->windowed_buffer);
     325          64 : }

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