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mss12.h
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1 /*
2  * Copyright (c) 2012 Konstantin Shishkov
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * Common header for Microsoft Screen 1 and 2
24  */
25 
26 #ifndef AVCODEC_MSS12_H
27 #define AVCODEC_MSS12_H
28 
29 #include "libavutil/intreadwrite.h"
30 #include "avcodec.h"
31 #include "get_bits.h"
32 #include "bytestream.h"
33 
34 #define MODEL_MIN_SYMS 2
35 #define MODEL_MAX_SYMS 256
36 #define THRESH_ADAPTIVE -1
37 #define THRESH_LOW 15
38 #define THRESH_HIGH 50
39 
40 typedef struct Model {
41  int16_t cum_prob[MODEL_MAX_SYMS + 1];
42  int16_t weights[MODEL_MAX_SYMS + 1];
43  uint8_t idx2sym[MODEL_MAX_SYMS + 1];
44  int num_syms;
45  int thr_weight, threshold;
46 } Model;
47 
48 typedef struct ArithCoder {
49  int low, high, value;
50  union {
51  GetBitContext *gb;
52  GetByteContext *gB;
53  } gbc;
54  int (*get_model_sym)(struct ArithCoder *c, Model *m);
55  int (*get_number) (struct ArithCoder *c, int n);
56 } ArithCoder;
57 
58 typedef struct PixContext {
59  int cache_size, num_syms;
60  uint8_t cache[12];
61  Model cache_model, full_model;
62  Model sec_models[15][4];
63  int special_initial_cache;
64 } PixContext;
65 
66 struct MSS12Context;
67 
68 typedef struct SliceContext {
69  struct MSS12Context *c;
70  Model intra_region, inter_region;
71  Model pivot, edge_mode, split_mode;
72  PixContext intra_pix_ctx, inter_pix_ctx;
73 } SliceContext;
74 
75 typedef struct MSS12Context {
76  AVCodecContext *avctx;
77  uint32_t pal[256];
78  uint8_t *pal_pic;
79  uint8_t *last_pal_pic;
80  int pal_stride;
81  uint8_t *mask;
82  int mask_stride;
83  uint8_t *rgb_pic;
84  uint8_t *last_rgb_pic;
85  int rgb_stride;
86  int free_colours;
87  int keyframe;
88  int mvX, mvY;
89  int corrupted;
90  int slice_split;
91  int full_model_syms;
92 } MSS12Context;
93 
94 int ff_mss12_decode_rect(SliceContext *ctx, ArithCoder *acoder,
95  int x, int y, int width, int height);
96 void ff_mss12_model_update(Model *m, int val);
97 void ff_mss12_slicecontext_reset(SliceContext *sc);
98 int ff_mss12_decode_init(MSS12Context *c, int version,
99  SliceContext *sc1, SliceContext *sc2);
100 int ff_mss12_decode_end(MSS12Context *ctx);
101 
102 #define ARITH_GET_BIT(prefix) \
103 static int prefix ## _get_bit(ArithCoder *c) \
104 { \
105  int range = c->high - c->low + 1; \
106  int bit = 2 * c->value - c->low >= c->high; \
107  \
108  if (bit) \
109  c->low += range >> 1; \
110  else \
111  c->high = c->low + (range >> 1) - 1; \
112  \
113  prefix ## _normalise(c); \
114  \
115  return bit; \
116 }
117 
118 #define ARITH_GET_MODEL_SYM(prefix) \
119 static int prefix ## _get_model_sym(ArithCoder *c, Model *m) \
120 { \
121  int idx, val; \
122  \
123  idx = prefix ## _get_prob(c, m->cum_prob); \
124  \
125  val = m->idx2sym[idx]; \
126  ff_mss12_model_update(m, idx); \
127  \
128  prefix ## _normalise(c); \
129  \
130  return val; \
131 }
132 
133 #endif /* AVCODEC_MSS12_H */
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