FFmpeg
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 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 <stddef.h>
29 #include "libavutil/internal.h"
30 #include "libavutil/intmath.h"
31 #include "jpegls.h"
32 
34 {
35  int i;
36 
37  state->twonear = state->near * 2 + 1;
38  state->range = (state->maxval + state->twonear - 1) / state->twonear + 1;
39 
40  // QBPP = ceil(log2(RANGE))
41  for (state->qbpp = 0; (1 << state->qbpp) < state->range; state->qbpp++)
42  ;
43 
44  state->bpp = FFMAX(av_log2(state->maxval) + 1, 2);
45  state->limit = 2*(state->bpp + FFMAX(state->bpp, 8)) - state->qbpp;
46 
47  for (i = 0; i < 367; i++) {
48  state->A[i] = FFMAX(state->range + 32 >> 6, 2);
49  state->N[i] = 1;
50  }
51 }
52 
53 /**
54  * Custom value clipping function used in T1, T2, T3 calculation
55  */
56 static inline int iso_clip(int v, int vmin, int vmax)
57 {
58  if (v > vmax || v < vmin)
59  return vmin;
60  else
61  return v;
62 }
63 
65 {
66  const int basic_t1 = 3;
67  const int basic_t2 = 7;
68  const int basic_t3 = 21;
69  int factor;
70 
71  if (s->maxval == 0 || reset_all)
72  s->maxval = (1 << s->bpp) - 1;
73 
74  if (s->maxval >= 128) {
75  factor = FFMIN(s->maxval, 4095) + 128 >> 8;
76 
77  if (s->T1 == 0 || reset_all)
78  s->T1 = iso_clip(factor * (basic_t1 - 2) + 2 + 3 * s->near,
79  s->near + 1, s->maxval);
80  if (s->T2 == 0 || reset_all)
81  s->T2 = iso_clip(factor * (basic_t2 - 3) + 3 + 5 * s->near,
82  s->T1, s->maxval);
83  if (s->T3 == 0 || reset_all)
84  s->T3 = iso_clip(factor * (basic_t3 - 4) + 4 + 7 * s->near,
85  s->T2, s->maxval);
86  } else {
87  factor = 256 / (s->maxval + 1);
88 
89  if (s->T1 == 0 || reset_all)
90  s->T1 = iso_clip(FFMAX(2, basic_t1 / factor + 3 * s->near),
91  s->near + 1, s->maxval);
92  if (s->T2 == 0 || reset_all)
93  s->T2 = iso_clip(FFMAX(3, basic_t2 / factor + 5 * s->near),
94  s->T1, s->maxval);
95  if (s->T3 == 0 || reset_all)
96  s->T3 = iso_clip(FFMAX(4, basic_t3 / factor + 7 * s->near),
97  s->T2, s->maxval);
98  }
99 
100  if (s->reset == 0 || reset_all)
101  s->reset = 64;
102  ff_dlog(NULL, "[JPEG-LS RESET] T=%i,%i,%i\n", s->T1, s->T2, s->T3);
103 }
state
static struct @318 state
FFMAX
#define FFMAX(a, b)
Definition: macros.h:47
JLSState
Definition: jpegls.h:36
jpegls.h
s
#define s(width, name)
Definition: cbs_vp9.c:257
NULL
#define NULL
Definition: coverity.c:32
for
for(j=16;j >0;--j)
Definition: h264pred_template.c:469
ff_dlog
#define ff_dlog(a,...)
Definition: tableprint_vlc.h:29
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:271
ff_jpegls_init_state
void ff_jpegls_init_state(JLSState *state)
Calculate initial JPEG-LS parameters.
Definition: jpegls.c:33
internal.h
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
ff_jpegls_reset_coding_parameters
void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all)
Calculate JPEG-LS codec values.
Definition: jpegls.c:64
factor
static const int factor[16]
Definition: vf_pp7.c:76
iso_clip
static int iso_clip(int v, int vmin, int vmax)
Custom value clipping function used in T1, T2, T3 calculation.
Definition: jpegls.c:56
av_log2
int av_log2(unsigned v)
Definition: intmath.c:26
intmath.h