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  1. /*
  2.  * AAC encoder utilities
  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 utilities
  25.  * @author Rostislav Pehlivanov ( atomnuker gmail com )
  26.  */
  27.  
  28. #ifndef AVCODEC_AACENC_UTILS_H
  29. #define AVCODEC_AACENC_UTILS_H
  30.  
  31. #include "aac.h"
  32. #include "aac_tablegen_decl.h"
  33. #include "aacenctab.h"
  34.  
  35. #define ROUND_STANDARD 0.4054f
  36. #define ROUND_TO_ZERO 0.1054f
  37. #define C_QUANT 0.4054f
  38.  
  39. static inline void abs_pow34_v(float *out, const float *in, const int size)
  40. {
  41.     int i;
  42.     for (i = 0; i < size; i++) {
  43.         float a = fabsf(in[i]);
  44.         out[i] = sqrtf(a * sqrtf(a));
  45.     }
  46. }
  47.  
  48. /**
  49.  * Quantize one coefficient.
  50.  * @return absolute value of the quantized coefficient
  51.  * @see 3GPP TS26.403 5.6.2 "Scalefactor determination"
  52.  */
  53. static inline int quant(float coef, const float Q, const float rounding)
  54. {
  55.     float a = coef * Q;
  56.     return sqrtf(a * sqrtf(a)) + rounding;
  57. }
  58.  
  59. static inline void quantize_bands(int *out, const float *in, const float *scaled,
  60.                                   int size, float Q34, int is_signed, int maxval,
  61.                                   const float rounding)
  62. {
  63.     int i;
  64.     double qc;
  65.     for (i = 0; i < size; i++) {
  66.         qc = scaled[i] * Q34;
  67.         out[i] = (int)FFMIN(qc + rounding, (double)maxval);
  68.         if (is_signed && in[i] < 0.0f) {
  69.             out[i] = -out[i];
  70.         }
  71.     }
  72. }
  73.  
  74. static inline float find_max_val(int group_len, int swb_size, const float *scaled)
  75. {
  76.     float maxval = 0.0f;
  77.     int w2, i;
  78.     for (w2 = 0; w2 < group_len; w2++) {
  79.         for (i = 0; i < swb_size; i++) {
  80.             maxval = FFMAX(maxval, scaled[w2*128+i]);
  81.         }
  82.     }
  83.     return maxval;
  84. }
  85.  
  86. static inline int find_min_book(float maxval, int sf)
  87. {
  88.     float Q = ff_aac_pow2sf_tab[POW_SF2_ZERO - sf + SCALE_ONE_POS - SCALE_DIV_512];
  89.     float Q34 = sqrtf(Q * sqrtf(Q));
  90.     int qmaxval, cb;
  91.     qmaxval = maxval * Q34 + C_QUANT;
  92.     if      (qmaxval ==  0) cb = 0;
  93.     else if (qmaxval ==  1) cb = 1;
  94.     else if (qmaxval ==  2) cb = 3;
  95.     else if (qmaxval <=  4) cb = 5;
  96.     else if (qmaxval <=  7) cb = 7;
  97.     else if (qmaxval <= 12) cb = 9;
  98.     else                    cb = 11;
  99.     return cb;
  100. }
  101.  
  102. /** Return the minimum scalefactor where the quantized coef does not clip. */
  103. static inline uint8_t coef2minsf(float coef)
  104. {
  105.     return av_clip_uint8(log2f(coef)*4 - 69 + SCALE_ONE_POS - SCALE_DIV_512);
  106. }
  107.  
  108. /** Return the maximum scalefactor where the quantized coef is not zero. */
  109. static inline uint8_t coef2maxsf(float coef)
  110. {
  111.     return av_clip_uint8(log2f(coef)*4 +  6 + SCALE_ONE_POS - SCALE_DIV_512);
  112. }
  113.  
  114. /*
  115.  * Returns the closest possible index to an array of float values, given a value.
  116.  */
  117. static inline int quant_array_idx(const float val, const float *arr, const int num)
  118. {
  119.     int i, index = 0;
  120.     float quant_min_err = INFINITY;
  121.     for (i = 0; i < num; i++) {
  122.         float error = (val - arr[i])*(val - arr[i]);
  123.         if (error < quant_min_err) {
  124.             quant_min_err = error;
  125.             index = i;
  126.         }
  127.     }
  128.     return index;
  129. }
  130.  
  131. #define ERROR_IF(cond, ...) \
  132.     if (cond) { \
  133.         av_log(avctx, AV_LOG_ERROR, __VA_ARGS__); \
  134.         return AVERROR(EINVAL); \
  135.     }
  136.  
  137. #define WARN_IF(cond, ...) \
  138.     if (cond) { \
  139.         av_log(avctx, AV_LOG_WARNING, __VA_ARGS__); \
  140.     }
  141.  
  142.  
  143. #endif /* AVCODEC_AACENC_UTILS_H */
  144.