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  1. /*
  2.  * JPEG-LS common code
  3.  * Copyright (c) 2003 Michael Niedermayer
  4.  * Copyright (c) 2006 Konstantin Shishkov
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. /**
  24.  * @file
  25.  * JPEG-LS common code.
  26.  */
  27.  
  28. #include "jpegls.h"
  29.  
  30. void ff_jpegls_init_state(JLSState *state)
  31. {
  32.     int i;
  33.  
  34.     state->twonear = state->near * 2 + 1;
  35.     state->range   = (state->maxval + state->twonear - 1) / state->twonear + 1;
  36.  
  37.     // QBPP = ceil(log2(RANGE))
  38.     for (state->qbpp = 0; (1 << state->qbpp) < state->range; state->qbpp++)
  39.         ;
  40.  
  41.     state->bpp   = FFMAX(av_log2(state->maxval) + 1, 2);
  42.     state->limit = 2*(state->bpp + FFMAX(state->bpp, 8)) - state->qbpp;
  43.  
  44.     for (i = 0; i < 367; i++) {
  45.         state->A[i] = FFMAX(state->range + 32 >> 6, 2);
  46.         state->N[i] = 1;
  47.     }
  48. }
  49.  
  50. /**
  51.  * Custom value clipping function used in T1, T2, T3 calculation
  52.  */
  53. static inline int iso_clip(int v, int vmin, int vmax)
  54. {
  55.     if (v > vmax || v < vmin)
  56.         return vmin;
  57.     else
  58.         return v;
  59. }
  60.  
  61. void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all)
  62. {
  63.     const int basic_t1 = 3;
  64.     const int basic_t2 = 7;
  65.     const int basic_t3 = 21;
  66.     int factor;
  67.  
  68.     if (s->maxval == 0 || reset_all)
  69.         s->maxval = (1 << s->bpp) - 1;
  70.  
  71.     if (s->maxval >= 128) {
  72.         factor = FFMIN(s->maxval, 4095) + 128 >> 8;
  73.  
  74.         if (s->T1 == 0 || reset_all)
  75.             s->T1 = iso_clip(factor * (basic_t1 - 2) + 2 + 3 * s->near,
  76.                              s->near + 1, s->maxval);
  77.         if (s->T2 == 0 || reset_all)
  78.             s->T2 = iso_clip(factor * (basic_t2 - 3) + 3 + 5 * s->near,
  79.                              s->T1, s->maxval);
  80.         if (s->T3 == 0 || reset_all)
  81.             s->T3 = iso_clip(factor * (basic_t3 - 4) + 4 + 7 * s->near,
  82.                              s->T2, s->maxval);
  83.     } else {
  84.         factor = 256 / (s->maxval + 1);
  85.  
  86.         if (s->T1 == 0 || reset_all)
  87.             s->T1 = iso_clip(FFMAX(2, basic_t1 / factor + 3 * s->near),
  88.                              s->near + 1, s->maxval);
  89.         if (s->T2 == 0 || reset_all)
  90.             s->T2 = iso_clip(FFMAX(3, basic_t2 / factor + 5 * s->near),
  91.                              s->T1, s->maxval);
  92.         if (s->T3 == 0 || reset_all)
  93.             s->T3 = iso_clip(FFMAX(4, basic_t3 / factor + 7 * s->near),
  94.                              s->T2, s->maxval);
  95.     }
  96.  
  97.     if (s->reset == 0 || reset_all)
  98.         s->reset = 64;
  99.     av_dlog(NULL, "[JPEG-LS RESET] T=%i,%i,%i\n", s->T1, s->T2, s->T3);
  100. }
  101.