FFmpeg
jpegls.c
Go to the documentation of this file.
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 "libavutil/log.h"
32 #include "jpegls.h"
33 
35 {
36  int i;
37 
38  state->twonear = state->near * 2 + 1;
39  state->range = (state->maxval + state->twonear - 1) / state->twonear + 1;
40 
41  // QBPP = ceil(log2(RANGE))
42  for (state->qbpp = 0; (1 << state->qbpp) < state->range; state->qbpp++)
43  ;
44 
45  state->bpp = FFMAX(av_log2(state->maxval) + 1, 2);
46  state->limit = 2*(state->bpp + FFMAX(state->bpp, 8)) - state->qbpp;
47 
48  for (i = 0; i < 367; i++) {
49  state->A[i] = FFMAX(state->range + 32 >> 6, 2);
50  state->N[i] = 1;
51  }
52 }
53 
54 /**
55  * Custom value clipping function used in T1, T2, T3 calculation
56  */
57 static inline int iso_clip(int v, int vmin, int vmax)
58 {
59  if (v > vmax || v < vmin)
60  return vmin;
61  else
62  return v;
63 }
64 
66 {
67  const int basic_t1 = 3;
68  const int basic_t2 = 7;
69  const int basic_t3 = 21;
70  int factor;
71 
72  if (s->maxval == 0 || reset_all)
73  s->maxval = (1 << s->bpp) - 1;
74 
75  if (s->maxval >= 128) {
76  factor = FFMIN(s->maxval, 4095) + 128 >> 8;
77 
78  if (s->T1 == 0 || reset_all)
79  s->T1 = iso_clip(factor * (basic_t1 - 2) + 2 + 3 * s->near,
80  s->near + 1, s->maxval);
81  if (s->T2 == 0 || reset_all)
82  s->T2 = iso_clip(factor * (basic_t2 - 3) + 3 + 5 * s->near,
83  s->T1, s->maxval);
84  if (s->T3 == 0 || reset_all)
85  s->T3 = iso_clip(factor * (basic_t3 - 4) + 4 + 7 * s->near,
86  s->T2, s->maxval);
87  } else {
88  factor = 256 / (s->maxval + 1);
89 
90  if (s->T1 == 0 || reset_all)
91  s->T1 = iso_clip(FFMAX(2, basic_t1 / factor + 3 * s->near),
92  s->near + 1, s->maxval);
93  if (s->T2 == 0 || reset_all)
94  s->T2 = iso_clip(FFMAX(3, basic_t2 / factor + 5 * s->near),
95  s->T1, s->maxval);
96  if (s->T3 == 0 || reset_all)
97  s->T3 = iso_clip(FFMAX(4, basic_t3 / factor + 7 * s->near),
98  s->T2, s->maxval);
99  }
100 
101  if (s->reset == 0 || reset_all)
102  s->reset = 64;
103  ff_dlog(NULL, "[JPEG-LS RESET] T=%i,%i,%i\n", s->T1, s->T2, s->T3);
104 }
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:198
NULL
#define NULL
Definition: coverity.c:32
ff_dlog
#define ff_dlog(a,...)
Definition: tableprint_vlc.h:28
for
for(k=2;k<=8;++k)
Definition: h264pred_template.c:425
log.h
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
ff_jpegls_init_state
void ff_jpegls_init_state(JLSState *state)
Calculate initial JPEG-LS parameters.
Definition: jpegls.c:34
internal.h
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
state
static struct @416 state
ff_jpegls_reset_coding_parameters
void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all)
Calculate JPEG-LS codec values.
Definition: jpegls.c:65
factor
static const int factor[16]
Definition: vf_pp7.c:79
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:57
av_log2
int av_log2(unsigned v)
Definition: intmath.c:26
intmath.h