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jpegls.h
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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 #ifndef AVCODEC_JPEGLS_H
29 #define AVCODEC_JPEGLS_H
30 
31 #include "libavutil/common.h"
32 #include "avcodec.h"
33 
34 typedef struct JpeglsContext {
37 
38 typedef struct JLSState {
39  int T1, T2, T3;
40  int A[367], B[367], C[365], N[367];
42  int near, twonear;
43  int run_index[4];
44 } JLSState;
45 
46 extern const uint8_t ff_log2_run[32];
47 
48 /**
49  * Calculate initial JPEG-LS parameters
50  */
52 
53 /**
54  * Calculate quantized gradient value, used for context determination
55  */
56 static inline int ff_jpegls_quantize(JLSState *s, int v)
57 {
58  if (v == 0)
59  return 0;
60  if (v < 0) {
61  if (v <= -s->T3)
62  return -4;
63  if (v <= -s->T2)
64  return -3;
65  if (v <= -s->T1)
66  return -2;
67  if (v < -s->near)
68  return -1;
69  return 0;
70  } else {
71  if (v <= s->near)
72  return 0;
73  if (v < s->T1)
74  return 1;
75  if (v < s->T2)
76  return 2;
77  if (v < s->T3)
78  return 3;
79  return 4;
80  }
81 }
82 
83 /**
84  * Calculate JPEG-LS codec values
85  */
86 void ff_jpegls_reset_coding_parameters(JLSState *s, int reset_all);
87 
88 static inline void ff_jpegls_downscale_state(JLSState *state, int Q)
89 {
90  if (state->N[Q] == state->reset) {
91  state->A[Q] >>= 1;
92  state->B[Q] >>= 1;
93  state->N[Q] >>= 1;
94  }
95  state->N[Q]++;
96 }
97 
99  int Q, int err)
100 {
101  if(FFABS(err) > 0xFFFF)
102  return -0x10000;
103  state->A[Q] += FFABS(err);
104  err *= state->twonear;
105  state->B[Q] += err;
106 
107  ff_jpegls_downscale_state(state, Q);
108 
109  if (state->B[Q] <= -state->N[Q]) {
110  state->B[Q] = FFMAX(state->B[Q] + state->N[Q], 1 - state->N[Q]);
111  if (state->C[Q] > -128)
112  state->C[Q]--;
113  } else if (state->B[Q] > 0) {
114  state->B[Q] = FFMIN(state->B[Q] - state->N[Q], 0);
115  if (state->C[Q] < 127)
116  state->C[Q]++;
117  }
118 
119  return err;
120 }
121 
122 #define R(a, i) (bits == 8 ? ((uint8_t *)(a))[i] : ((uint16_t *)(a))[i])
123 #define W(a, i, v) (bits == 8 ? (((uint8_t *)(a))[i] = v) : (((uint16_t *)(a))[i] = v))
124 
125 #endif /* AVCODEC_JPEGLS_H */