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| 4349 | Serge | 1 | /* |
| 2 | * Copyright (c) 1990 James Ashton - Sydney University |
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| 3 | * Copyright (c) 2012 Stefano Sabatini |
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| 4 | * |
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| 5 | * This file is part of FFmpeg. |
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| 6 | * |
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| 7 | * FFmpeg is free software; you can redistribute it and/or |
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| 8 | * modify it under the terms of the GNU Lesser General Public |
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| 9 | * License as published by the Free Software Foundation; either |
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| 10 | * version 2.1 of the License, or (at your option) any later version. |
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| 11 | * |
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| 12 | * FFmpeg is distributed in the hope that it will be useful, |
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| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 15 | * Lesser General Public License for more details. |
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| 16 | * |
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| 17 | * You should have received a copy of the GNU Lesser General Public |
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| 18 | * License along with FFmpeg; if not, write to the Free Software |
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| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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| 20 | */ |
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| 21 | |||
| 22 | /** |
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| 23 | * @file |
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| 24 | * X-Face common definitions. |
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| 25 | */ |
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| 26 | |||
| 27 | #include |
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| 28 | |||
| 29 | /* define the face size - 48x48x1 */ |
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| 30 | #define XFACE_WIDTH 48 |
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| 31 | #define XFACE_HEIGHT 48 |
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| 32 | #define XFACE_PIXELS (XFACE_WIDTH * XFACE_HEIGHT) |
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| 33 | |||
| 34 | /* compressed output uses the full range of printable characters. |
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| 35 | * In ASCII these are in a contiguous block so we just need to know |
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| 36 | * the first and last. The total number of printables is needed too. */ |
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| 37 | #define XFACE_FIRST_PRINT '!' |
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| 38 | #define XFACE_LAST_PRINT '~' |
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| 39 | #define XFACE_PRINTS (XFACE_LAST_PRINT - XFACE_FIRST_PRINT + 1) |
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| 40 | |||
| 41 | /* |
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| 42 | * Image is encoded as a big integer, using characters from '~' to |
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| 43 | * '!', for a total of 92 symbols. In order to express 48x48=2304 |
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| 44 | * bits, we need a total of 354 digits, as given by: |
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| 45 | * ceil(lg_92(2^2304)) = 354 |
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| 46 | */ |
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| 47 | #define XFACE_MAX_DIGITS 354 |
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| 48 | |||
| 49 | #define XFACE_BITSPERWORD 8 |
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| 50 | #define XFACE_WORDCARRY (1 << XFACE_BITSPERWORD) |
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| 51 | #define XFACE_WORDMASK (XFACE_WORDCARRY - 1) |
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| 52 | |||
| 53 | #define XFACE_MAX_WORDS ((XFACE_PIXELS * 2 + XFACE_BITSPERWORD - 1) / XFACE_BITSPERWORD) |
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| 54 | |||
| 55 | /* Portable, very large unsigned integer arithmetic is needed. |
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| 56 | * Implementation uses arrays of WORDs. */ |
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| 57 | typedef struct { |
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| 58 | int nb_words; |
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| 59 | uint8_t words[XFACE_MAX_WORDS]; |
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| 60 | } BigInt; |
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| 61 | |||
| 62 | /** |
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| 63 | * Add a to b storing the result in b. |
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| 64 | */ |
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| 65 | void ff_big_add(BigInt *b, uint8_t a); |
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| 66 | |||
| 67 | /** |
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| 68 | * Divide b by a storing the result in b and the remainder in the word |
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| 69 | * pointed to by r. |
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| 70 | */ |
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| 71 | void ff_big_div(BigInt *b, uint8_t a, uint8_t *r); |
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| 72 | |||
| 73 | /** |
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| 74 | * Multiply a by b storing the result in b. |
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| 75 | */ |
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| 76 | void ff_big_mul(BigInt *b, uint8_t a); |
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| 77 | |||
| 78 | /* Each face is encoded using 9 octrees of 16x16 each. Each level of the |
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| 79 | * trees has varying probabilities of being white, grey or black. |
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| 80 | * The table below is based on sampling many faces */ |
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| 81 | enum XFaceColor { XFACE_COLOR_BLACK = 0, XFACE_COLOR_GREY, XFACE_COLOR_WHITE }; |
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| 82 | |||
| 83 | /* Data of varying probabilities are encoded by a value in the range 0 - 255. |
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| 84 | * The probability of the data determines the range of possible encodings. |
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| 85 | * Offset gives the first possible encoding of the range. */ |
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| 86 | typedef struct { |
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| 87 | int range; |
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| 88 | int offset; |
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| 89 | } ProbRange; |
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| 90 | |||
| 91 | extern const ProbRange ff_xface_probranges_per_level[4][3]; |
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| 92 | |||
| 93 | extern const ProbRange ff_xface_probranges_2x2[16]; |
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| 94 | |||
| 95 | void ff_xface_generate_face(uint8_t *dst, uint8_t * const src); |