Libav
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 {
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  if (state->bpp < 8)
42  state->limit = 2 * state->bpp - state->qbpp + 16;
43  else
44  state->limit = 4 * state->bpp - state->qbpp;
45 
46  for (i = 0; i < 367; i++) {
47  state->A[i] = FFMAX(state->range + 32 >> 6, 2);
48  state->N[i] = 1;
49  }
50 }
51 
55 static inline int iso_clip(int v, int vmin, int vmax)
56 {
57  if (v > vmax || v < vmin)
58  return vmin;
59  else
60  return v;
61 }
62 
64 {
65  const int basic_t1 = 3;
66  const int basic_t2 = 7;
67  const int basic_t3 = 21;
68  int factor;
69 
70  if (s->maxval == 0 || reset_all)
71  s->maxval = (1 << s->bpp) - 1;
72 
73  if (s->maxval >= 128) {
74  factor = FFMIN(s->maxval, 4095) + 128 >> 8;
75 
76  if (s->T1 == 0 || reset_all)
77  s->T1 = iso_clip(factor * (basic_t1 - 2) + 2 + 3 * s->near,
78  s->near + 1, s->maxval);
79  if (s->T2 == 0 || reset_all)
80  s->T2 = iso_clip(factor * (basic_t2 - 3) + 3 + 5 * s->near,
81  s->T1, s->maxval);
82  if (s->T3 == 0 || reset_all)
83  s->T3 = iso_clip(factor * (basic_t3 - 4) + 4 + 7 * s->near,
84  s->T2, s->maxval);
85  } else {
86  factor = 256 / (s->maxval + 1);
87 
88  if (s->T1 == 0 || reset_all)
89  s->T1 = iso_clip(FFMAX(2, basic_t1 / factor + 3 * s->near),
90  s->near + 1, s->maxval);
91  if (s->T2 == 0 || reset_all)
92  s->T2 = iso_clip(FFMAX(3, basic_t2 / factor + 5 * s->near),
93  s->T1, s->maxval);
94  if (s->T3 == 0 || reset_all)
95  s->T3 = iso_clip(FFMAX(4, basic_t3 / factor + 7 * s->near),
96  s->T2, s->maxval);
97  }
98 
99  if (s->reset == 0 || reset_all)
100  s->reset = 64;
101  av_dlog(NULL, "[JPEG-LS RESET] T=%i,%i,%i\n", s->T1, s->T2, s->T3);
102 }
int reset
Definition: jpegls.h:41
int T2
Definition: jpegls.h:39
int twonear
Definition: jpegls.h:42
av_dlog(ac->avr,"%d samples - audio_convert: %s to %s (%s)\n", len, av_get_sample_fmt_name(ac->in_fmt), av_get_sample_fmt_name(ac->out_fmt), use_generic?ac->func_descr_generic:ac->func_descr)
int limit
Definition: jpegls.h:41
int bpp
Definition: jpegls.h:41
int maxval
Definition: jpegls.h:41
static int iso_clip(int v, int vmin, int vmax)
Custom value clipping function used in T1, T2, T3 calculation.
Definition: jpegls.c:55
void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all)
Calculate JPEG-LS codec values.
Definition: jpegls.c:63
#define FFMAX(a, b)
Definition: common.h:55
int near
Definition: jpegls.h:42
#define FFMIN(a, b)
Definition: common.h:57
int qbpp
Definition: jpegls.h:41
NULL
Definition: eval.c:55
int A[367]
Definition: jpegls.h:40
JPEG-LS common code.
int T1
Definition: jpegls.h:39
int range
Definition: jpegls.h:41
int N[367]
Definition: jpegls.h:40
static uint32_t state
Definition: trasher.c:27
int T3
Definition: jpegls.h:39
void ff_jpegls_init_state(JLSState *state)
Calculate initial JPEG-LS parameters.
Definition: jpegls.c:30
for(j=16;j >0;--j)