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101 lines
3.1 KiB
101 lines
3.1 KiB
/* |
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* Copyright (c) 1990 James Ashton - Sydney University |
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* Copyright (c) 2012 Stefano Sabatini |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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/** |
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* @file |
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* X-Face common definitions. |
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*/ |
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#ifndef AVCODEC_XFACE_H |
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#define AVCODEC_XFACE_H |
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#include <stdint.h> |
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/* define the face size - 48x48x1 */ |
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#define XFACE_WIDTH 48 |
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#define XFACE_HEIGHT 48 |
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#define XFACE_PIXELS (XFACE_WIDTH * XFACE_HEIGHT) |
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/* compressed output uses the full range of printable characters. |
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* In ASCII these are in a contiguous block so we just need to know |
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* the first and last. The total number of printables is needed too. */ |
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#define XFACE_FIRST_PRINT '!' |
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#define XFACE_LAST_PRINT '~' |
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#define XFACE_PRINTS (XFACE_LAST_PRINT - XFACE_FIRST_PRINT + 1) |
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/* |
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* Image is encoded as a big integer, using characters from '~' to |
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* '!', for a total of 94 symbols. In order to express |
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* 48x48 pixels with the worst case encoding 666 symbols should |
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* be sufficient. |
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*/ |
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#define XFACE_MAX_DIGITS 666 |
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#define XFACE_BITSPERWORD 8 |
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#define XFACE_WORDCARRY (1 << XFACE_BITSPERWORD) |
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#define XFACE_WORDMASK (XFACE_WORDCARRY - 1) |
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// This must be larger or equal to log256(94^XFACE_MAX_DIGITS) |
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#define XFACE_MAX_WORDS 546 |
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/* Portable, very large unsigned integer arithmetic is needed. |
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* Implementation uses arrays of WORDs. */ |
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typedef struct { |
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int nb_words; |
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uint8_t words[XFACE_MAX_WORDS]; |
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} BigInt; |
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/** |
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* Add a to b storing the result in b. |
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*/ |
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void ff_big_add(BigInt *b, uint8_t a); |
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/** |
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* Divide b by a storing the result in b and the remainder in the word |
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* pointed to by r. |
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*/ |
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void ff_big_div(BigInt *b, uint8_t a, uint8_t *r); |
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/** |
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* Multiply a by b storing the result in b. |
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*/ |
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void ff_big_mul(BigInt *b, uint8_t a); |
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/* Each face is encoded using 9 octrees of 16x16 each. Each level of the |
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* trees has varying probabilities of being white, grey or black. |
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* The table below is based on sampling many faces */ |
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enum XFaceColor { XFACE_COLOR_BLACK = 0, XFACE_COLOR_GREY, XFACE_COLOR_WHITE }; |
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/* Data of varying probabilities are encoded by a value in the range 0 - 255. |
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* The probability of the data determines the range of possible encodings. |
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* Offset gives the first possible encoding of the range. */ |
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typedef struct { |
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uint8_t range; |
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uint8_t offset; |
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} ProbRange; |
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extern const ProbRange ff_xface_probranges_per_level[4][3]; |
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extern const ProbRange ff_xface_probranges_2x2[16]; |
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void ff_xface_generate_face(uint8_t *dst, uint8_t * const src); |
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#endif /* AVCODEC_XFACE_H */
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