2 * Copyright (c) 2012 Konstantin Shishkov
4 * This file is part of FFmpeg.
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.
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.
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
23 * Common header for Microsoft Screen 1 and 2
26 #ifndef AVCODEC_MSS12_H
27 #define AVCODEC_MSS12_H
29 #include "libavutil/intreadwrite.h"
32 #include "bytestream.h"
34 #define MODEL_MIN_SYMS 2
35 #define MODEL_MAX_SYMS 256
36 #define THRESH_ADAPTIVE -1
38 #define THRESH_HIGH 50
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];
45 int thr_weight
, threshold
;
48 typedef struct ArithCoder
{
54 int (*get_model_sym
)(struct ArithCoder
*c
, Model
*m
);
55 int (*get_number
) (struct ArithCoder
*c
, int n
);
58 typedef struct PixContext
{
59 int cache_size
, num_syms
;
61 Model cache_model
, full_model
;
62 Model sec_models
[15][4];
63 int special_initial_cache
;
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
;
75 typedef struct MSS12Context
{
76 AVCodecContext
*avctx
;
79 uint8_t *last_pal_pic
;
84 uint8_t *last_rgb_pic
;
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
);
102 #define ARITH_GET_BIT(prefix) \
103 static int prefix ## _get_bit(ArithCoder *c) \
105 int range = c->high - c->low + 1; \
106 int bit = 2 * c->value - c->low >= c->high; \
109 c->low += range >> 1; \
111 c->high = c->low + (range >> 1) - 1; \
113 prefix ## _normalise(c); \
118 #define ARITH_GET_MODEL_SYM(prefix) \
119 static int prefix ## _get_model_sym(ArithCoder *c, Model *m) \
123 idx = prefix ## _get_prob(c, m->cum_prob); \
125 val = m->idx2sym[idx]; \
126 ff_mss12_model_update(m, idx); \
128 prefix ## _normalise(c); \
133 #endif /* AVCODEC_MSS12_H */