LCOV - code coverage report
Current view: top level - libavcodec - lpc.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 41 42 97.6 %
Date: 2017-12-12 11:08:38 Functions: 3 3 100.0 %

          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             : #ifndef AVCODEC_LPC_H
      23             : #define AVCODEC_LPC_H
      24             : 
      25             : #include <stdint.h>
      26             : #include "libavutil/avassert.h"
      27             : #include "libavutil/lls.h"
      28             : #include "aac_defines.h"
      29             : 
      30             : #define ORDER_METHOD_EST     0
      31             : #define ORDER_METHOD_2LEVEL  1
      32             : #define ORDER_METHOD_4LEVEL  2
      33             : #define ORDER_METHOD_8LEVEL  3
      34             : #define ORDER_METHOD_SEARCH  4
      35             : #define ORDER_METHOD_LOG     5
      36             : 
      37             : #define MIN_LPC_ORDER        1
      38             : #define MAX_LPC_ORDER       32
      39             : 
      40             : /**
      41             :  * LPC analysis type
      42             :  */
      43             : enum FFLPCType {
      44             :     FF_LPC_TYPE_DEFAULT     = -1, ///< use the codec default LPC type
      45             :     FF_LPC_TYPE_NONE        =  0, ///< do not use LPC prediction or use all zero coefficients
      46             :     FF_LPC_TYPE_FIXED       =  1, ///< fixed LPC coefficients
      47             :     FF_LPC_TYPE_LEVINSON    =  2, ///< Levinson-Durbin recursion
      48             :     FF_LPC_TYPE_CHOLESKY    =  3, ///< Cholesky factorization
      49             :     FF_LPC_TYPE_NB              , ///< Not part of ABI
      50             : };
      51             : 
      52             : typedef struct LPCContext {
      53             :     int blocksize;
      54             :     int max_order;
      55             :     enum FFLPCType lpc_type;
      56             :     double *windowed_buffer;
      57             :     double *windowed_samples;
      58             : 
      59             :     /**
      60             :      * Apply a Welch window to an array of input samples.
      61             :      * The output samples have the same scale as the input, but are in double
      62             :      * sample format.
      63             :      * @param data    input samples
      64             :      * @param len     number of input samples
      65             :      * @param w_data  output samples
      66             :      */
      67             :     void (*lpc_apply_welch_window)(const int32_t *data, int len,
      68             :                                    double *w_data);
      69             :     /**
      70             :      * Perform autocorrelation on input samples with delay of 0 to lag.
      71             :      * @param data  input samples.
      72             :      *              constraints: no alignment needed, but must have at
      73             :      *              least lag*sizeof(double) valid bytes preceding it, and
      74             :      *              size must be at least (len+1)*sizeof(double) if data is
      75             :      *              16-byte aligned or (len+2)*sizeof(double) if data is
      76             :      *              unaligned.
      77             :      * @param len   number of input samples to process
      78             :      * @param lag   maximum delay to calculate
      79             :      * @param autoc output autocorrelation coefficients.
      80             :      *              constraints: array size must be at least lag+1.
      81             :      */
      82             :     void (*lpc_compute_autocorr)(const double *data, int len, int lag,
      83             :                                  double *autoc);
      84             : 
      85             :     // TODO: these should be allocated to reduce ABI compatibility issues
      86             :     LLSModel lls_models[2];
      87             : } LPCContext;
      88             : 
      89             : 
      90             : /**
      91             :  * Calculate LPC coefficients for multiple orders
      92             :  */
      93             : int ff_lpc_calc_coefs(LPCContext *s,
      94             :                       const int32_t *samples, int blocksize, int min_order,
      95             :                       int max_order, int precision,
      96             :                       int32_t coefs[][MAX_LPC_ORDER], int *shift,
      97             :                       enum FFLPCType lpc_type, int lpc_passes,
      98             :                       int omethod, int min_shift, int max_shift, int zero_shift);
      99             : 
     100             : int ff_lpc_calc_ref_coefs(LPCContext *s,
     101             :                           const int32_t *samples, int order, double *ref);
     102             : 
     103             : double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len,
     104             :                                int order, double *ref);
     105             : 
     106             : /**
     107             :  * Initialize LPCContext.
     108             :  */
     109             : int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
     110             :                 enum FFLPCType lpc_type);
     111             : void ff_lpc_init_x86(LPCContext *s);
     112             : 
     113             : /**
     114             :  * Uninitialize LPCContext.
     115             :  */
     116             : void ff_lpc_end(LPCContext *s);
     117             : 
     118             : #if USE_FIXED
     119             : typedef int LPC_TYPE;
     120             : typedef unsigned LPC_TYPE_U;
     121             : #else
     122             : #ifdef LPC_USE_DOUBLE
     123             : typedef double LPC_TYPE;
     124             : typedef double LPC_TYPE_U;
     125             : #else
     126             : typedef float LPC_TYPE;
     127             : typedef float LPC_TYPE_U;
     128             : #endif
     129             : #endif // USE_FIXED
     130             : 
     131             : /**
     132             :  * Schur recursion.
     133             :  * Produces reflection coefficients from autocorrelation data.
     134             :  */
     135        2009 : static inline void compute_ref_coefs(const LPC_TYPE *autoc, int max_order,
     136             :                                      LPC_TYPE *ref, LPC_TYPE *error)
     137             : {
     138             :     int i, j;
     139             :     LPC_TYPE err;
     140             :     LPC_TYPE gen0[MAX_LPC_ORDER], gen1[MAX_LPC_ORDER];
     141             : 
     142       24797 :     for (i = 0; i < max_order; i++)
     143       22788 :         gen0[i] = gen1[i] = autoc[i + 1];
     144             : 
     145        2009 :     err    = autoc[0];
     146        2009 :     ref[0] = -gen1[0] / err;
     147        2009 :     err   +=  gen1[0] * ref[0];
     148        2009 :     if (error)
     149        2009 :         error[0] = err;
     150       22788 :     for (i = 1; i < max_order; i++) {
     151      141493 :         for (j = 0; j < max_order - i; j++) {
     152      120714 :             gen1[j] = gen1[j + 1] + ref[i - 1] * gen0[j];
     153      120714 :             gen0[j] = gen1[j + 1] * ref[i - 1] + gen0[j];
     154             :         }
     155       20779 :         ref[i] = -gen1[0] / err;
     156       20779 :         err   +=  gen1[0] * ref[i];
     157       20779 :         if (error)
     158       20779 :             error[i] = err;
     159             :     }
     160        2009 : }
     161             : 
     162             : /**
     163             :  * Levinson-Durbin recursion.
     164             :  * Produce LPC coefficients from autocorrelation data.
     165             :  */
     166       37695 : static inline int AAC_RENAME(compute_lpc_coefs)(const LPC_TYPE *autoc, int max_order,
     167             :                                     LPC_TYPE *lpc, int lpc_stride, int fail,
     168             :                                     int normalize)
     169             : {
     170             :     int i, j;
     171       37695 :     LPC_TYPE err = 0;
     172       37695 :     LPC_TYPE *lpc_last = lpc;
     173             : 
     174             :     av_assert2(normalize || !fail);
     175             : 
     176       37695 :     if (normalize)
     177       28753 :         err = *autoc++;
     178             : 
     179       37695 :     if (fail && (autoc[max_order - 1] == 0 || err <= 0))
     180           2 :         return -1;
     181             : 
     182      644720 :     for(i=0; i<max_order; i++) {
     183      607027 :         LPC_TYPE r = AAC_SRA_R(-autoc[i], 5);
     184             : 
     185      607027 :         if (normalize) {
     186     7878642 :             for(j=0; j<i; j++)
     187     7330478 :                 r -= lpc_last[j] * autoc[i-j-1];
     188             : 
     189      548164 :             r /= err;
     190      548164 :             err *= FIXR(1.0) - (r * r);
     191             :         }
     192             : 
     193      607027 :         lpc[i] = r;
     194             : 
     195     4534861 :         for(j=0; j < (i+1)>>1; j++) {
     196     3927834 :             LPC_TYPE f = lpc_last[    j];
     197     3927834 :             LPC_TYPE b = lpc_last[i-1-j];
     198     3927834 :             lpc[    j] = f + (LPC_TYPE_U)AAC_MUL26(r, b);
     199     3927834 :             lpc[i-1-j] = b + (LPC_TYPE_U)AAC_MUL26(r, f);
     200             :         }
     201             : 
     202      607027 :         if (fail && err < 0)
     203           0 :             return -1;
     204             : 
     205      607027 :         lpc_last = lpc;
     206      607027 :         lpc += lpc_stride;
     207             :     }
     208             : 
     209       37693 :     return 0;
     210             : }
     211             : 
     212             : #endif /* AVCODEC_LPC_H */

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