| 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 */ |