xref: /third_party/ffmpeg/libavcodec/mss12.h (revision cabdff1a) 
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
40typedef 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
48typedef struct ArithCoder {
49    int low, high, value;
50    int overread;
51#define MAX_OVERREAD 16
52    union {
53        GetBitContext *gb;
54        GetByteContext *gB;
55    } gbc;
56    int (*get_model_sym)(struct ArithCoder *c, Model *m);
57    int (*get_number)   (struct ArithCoder *c, int n);
58} ArithCoder;
59
60typedef struct PixContext {
61    int cache_size, num_syms;
62    uint8_t cache[12];
63    Model cache_model, full_model;
64    Model sec_models[15][4];
65    int special_initial_cache;
66} PixContext;
67
68struct MSS12Context;
69
70typedef struct SliceContext {
71    const struct MSS12Context *c;
72    Model      intra_region, inter_region;
73    Model      pivot, edge_mode, split_mode;
74    PixContext intra_pix_ctx, inter_pix_ctx;
75} SliceContext;
76
77typedef struct MSS12Context {
78    AVCodecContext *avctx;
79    uint32_t       pal[256];
80    uint8_t        *pal_pic;
81    uint8_t        *last_pal_pic;
82    ptrdiff_t      pal_stride;
83    uint8_t        *mask;
84    ptrdiff_t      mask_stride;
85    uint8_t        *rgb_pic;
86    uint8_t        *last_rgb_pic;
87    ptrdiff_t      rgb_stride;
88    int            free_colours;
89    int            keyframe;
90    int            mvX, mvY;
91    int            corrupted;
92    int            slice_split;
93    int            full_model_syms;
94} MSS12Context;
95
96int ff_mss12_decode_rect(SliceContext *ctx, ArithCoder *acoder,
97                         int x, int y, int width, int height);
98void ff_mss12_model_update(Model *m, int val);
99void ff_mss12_slicecontext_reset(SliceContext *sc);
100int ff_mss12_decode_init(MSS12Context *c, int version,
101                         SliceContext *sc1, SliceContext *sc2);
102int ff_mss12_decode_end(MSS12Context *ctx);
103
104#define ARITH_GET_BIT(prefix)                                           \
105static int prefix ## _get_bit(ArithCoder *c)                            \
106{                                                                       \
107    int range = c->high - c->low + 1;                                   \
108    int bit   = 2 * c->value - c->low >= c->high;                       \
109                                                                        \
110    if (bit)                                                            \
111        c->low += range >> 1;                                           \
112    else                                                                \
113        c->high = c->low + (range >> 1) - 1;                            \
114                                                                        \
115    prefix ## _normalise(c);                                            \
116                                                                        \
117    return bit;                                                         \
118}
119
120#define ARITH_GET_MODEL_SYM(prefix)                                     \
121static int prefix ## _get_model_sym(ArithCoder *c, Model *m)            \
122{                                                                       \
123    int idx, val;                                                       \
124                                                                        \
125    idx = prefix ## _get_prob(c, m->cum_prob);                          \
126                                                                        \
127    val = m->idx2sym[idx];                                              \
128    ff_mss12_model_update(m, idx);                                      \
129                                                                        \
130    prefix ## _normalise(c);                                            \
131                                                                        \
132    return val;                                                         \
133}
134
135#endif /* AVCODEC_MSS12_H */
136