blob: d366fdb1dc778c4f5d2b8c7f8d810f21fbd76cca
| 1 | /* |
| 2 | * Copyright (c) 1990 James Ashton - Sydney University |
| 3 | * Copyright (c) 2012 Stefano Sabatini |
| 4 | * |
| 5 | * This file is part of FFmpeg. |
| 6 | * |
| 7 | * FFmpeg is free software; you can redistribute it and/or |
| 8 | * modify it under the terms of the GNU Lesser General Public |
| 9 | * License as published by the Free Software Foundation; either |
| 10 | * version 2.1 of the License, or (at your option) any later version. |
| 11 | * |
| 12 | * FFmpeg is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | * Lesser General Public License for more details. |
| 16 | * |
| 17 | * You should have received a copy of the GNU Lesser General Public |
| 18 | * License along with FFmpeg; if not, write to the Free Software |
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 20 | */ |
| 21 | |
| 22 | /** |
| 23 | * @file |
| 24 | * X-Face common definitions. |
| 25 | */ |
| 26 | |
| 27 | #ifndef AVCODEC_XFACE_H |
| 28 | #define AVCODEC_XFACE_H |
| 29 | |
| 30 | #include <stdint.h> |
| 31 | |
| 32 | /* define the face size - 48x48x1 */ |
| 33 | #define XFACE_WIDTH 48 |
| 34 | #define XFACE_HEIGHT 48 |
| 35 | #define XFACE_PIXELS (XFACE_WIDTH * XFACE_HEIGHT) |
| 36 | |
| 37 | /* compressed output uses the full range of printable characters. |
| 38 | * In ASCII these are in a contiguous block so we just need to know |
| 39 | * the first and last. The total number of printables is needed too. */ |
| 40 | #define XFACE_FIRST_PRINT '!' |
| 41 | #define XFACE_LAST_PRINT '~' |
| 42 | #define XFACE_PRINTS (XFACE_LAST_PRINT - XFACE_FIRST_PRINT + 1) |
| 43 | |
| 44 | /* |
| 45 | * Image is encoded as a big integer, using characters from '~' to |
| 46 | * '!', for a total of 94 symbols. In order to express |
| 47 | * 48x48 pixels with the worst case encoding 666 symbols should |
| 48 | * be sufficient. |
| 49 | */ |
| 50 | #define XFACE_MAX_DIGITS 666 |
| 51 | |
| 52 | #define XFACE_BITSPERWORD 8 |
| 53 | #define XFACE_WORDCARRY (1 << XFACE_BITSPERWORD) |
| 54 | #define XFACE_WORDMASK (XFACE_WORDCARRY - 1) |
| 55 | |
| 56 | // This must be larger or equal to log256(94^XFACE_MAX_DIGITS) |
| 57 | #define XFACE_MAX_WORDS 546 |
| 58 | |
| 59 | /* Portable, very large unsigned integer arithmetic is needed. |
| 60 | * Implementation uses arrays of WORDs. */ |
| 61 | typedef struct { |
| 62 | int nb_words; |
| 63 | uint8_t words[XFACE_MAX_WORDS]; |
| 64 | } BigInt; |
| 65 | |
| 66 | /** |
| 67 | * Add a to b storing the result in b. |
| 68 | */ |
| 69 | void ff_big_add(BigInt *b, uint8_t a); |
| 70 | |
| 71 | /** |
| 72 | * Divide b by a storing the result in b and the remainder in the word |
| 73 | * pointed to by r. |
| 74 | */ |
| 75 | void ff_big_div(BigInt *b, uint8_t a, uint8_t *r); |
| 76 | |
| 77 | /** |
| 78 | * Multiply a by b storing the result in b. |
| 79 | */ |
| 80 | void ff_big_mul(BigInt *b, uint8_t a); |
| 81 | |
| 82 | /* Each face is encoded using 9 octrees of 16x16 each. Each level of the |
| 83 | * trees has varying probabilities of being white, grey or black. |
| 84 | * The table below is based on sampling many faces */ |
| 85 | enum XFaceColor { XFACE_COLOR_BLACK = 0, XFACE_COLOR_GREY, XFACE_COLOR_WHITE }; |
| 86 | |
| 87 | /* Data of varying probabilities are encoded by a value in the range 0 - 255. |
| 88 | * The probability of the data determines the range of possible encodings. |
| 89 | * Offset gives the first possible encoding of the range. */ |
| 90 | typedef struct { |
| 91 | uint8_t range; |
| 92 | uint8_t offset; |
| 93 | } ProbRange; |
| 94 | |
| 95 | extern const ProbRange ff_xface_probranges_per_level[4][3]; |
| 96 | |
| 97 | extern const ProbRange ff_xface_probranges_2x2[16]; |
| 98 | |
| 99 | void ff_xface_generate_face(uint8_t *dst, uint8_t * const src); |
| 100 | |
| 101 | #endif /* AVCODEC_XFACE_H */ |
| 102 |