xref: /third_party/ffmpeg/libavcodec/jpegls.c (revision cabdff1a) 
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
33void ff_jpegls_init_state(JLSState *state)
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 */
56static 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
64void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all)
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}
104