jpegls.c
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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 Libav.
7  *
8  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
28 #include "jpegls.h"
29 
31  int i;
32 
33  state->twonear = state->near * 2 + 1;
34  state->range = ((state->maxval + state->twonear - 1) / state->twonear) + 1;
35 
36  // QBPP = ceil(log2(RANGE))
37  for(state->qbpp = 0; (1 << state->qbpp) < state->range; state->qbpp++);
38 
39  if(state->bpp < 8)
40  state->limit = 16 + 2 * state->bpp - state->qbpp;
41  else
42  state->limit = (4 * state->bpp) - 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 
54 static inline int iso_clip(int v, int vmin, int vmax){
55  if(v > vmax || v < vmin) return vmin;
56  else return v;
57 }
58 
60  const int basic_t1= 3;
61  const int basic_t2= 7;
62  const int basic_t3= 21;
63  int factor;
64 
65  if(s->maxval==0 || reset_all) s->maxval= (1 << s->bpp) - 1;
66 
67  if(s->maxval >=128){
68  factor= (FFMIN(s->maxval, 4095) + 128)>>8;
69 
70  if(s->T1==0 || reset_all)
71  s->T1= iso_clip(factor*(basic_t1-2) + 2 + 3*s->near, s->near+1, s->maxval);
72  if(s->T2==0 || reset_all)
73  s->T2= iso_clip(factor*(basic_t2-3) + 3 + 5*s->near, s->T1, s->maxval);
74  if(s->T3==0 || reset_all)
75  s->T3= iso_clip(factor*(basic_t3-4) + 4 + 7*s->near, s->T2, s->maxval);
76  }else{
77  factor= 256 / (s->maxval + 1);
78 
79  if(s->T1==0 || reset_all)
80  s->T1= iso_clip(FFMAX(2, basic_t1/factor + 3*s->near), s->near+1, s->maxval);
81  if(s->T2==0 || reset_all)
82  s->T2= iso_clip(FFMAX(3, basic_t2/factor + 5*s->near), s->T1, s->maxval);
83  if(s->T3==0 || reset_all)
84  s->T3= iso_clip(FFMAX(4, basic_t3/factor + 7*s->near), s->T2, s->maxval);
85  }
86 
87  if(s->reset==0 || reset_all) s->reset= 64;
88 // av_log(NULL, AV_LOG_DEBUG, "[JPEG-LS RESET] T=%i,%i,%i\n", s->T1, s->T2, s->T3);
89 }