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 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 60 typedef 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 68 struct MSS12Context; 69 70 typedef struct SliceContext { 71 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 77 typedef 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 96 int ff_mss12_decode_rect(SliceContext *ctx, ArithCoder *acoder, 97 int x, int y, int width, int height); 98 void ff_mss12_model_update(Model *m, int val); 99 void ff_mss12_slicecontext_reset(SliceContext *sc); 100 int ff_mss12_decode_init(MSS12Context *c, int version, 101 SliceContext *sc1, SliceContext *sc2); 102 int ff_mss12_decode_end(MSS12Context *ctx); 103 104 #define ARITH_GET_BIT(prefix) \ 105 static 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) \ 121 static 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