| 0,0 → 1,96 |
|---|
| /* |
| * Copyright (c) 1990 James Ashton - Sydney University |
| * Copyright (c) 2012 Stefano Sabatini |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| /** |
| * @file |
| * X-Face common definitions. |
| */ |
| |
| #include <stdint.h> |
| |
| /* define the face size - 48x48x1 */ |
| #define XFACE_WIDTH 48 |
| #define XFACE_HEIGHT 48 |
| #define XFACE_PIXELS (XFACE_WIDTH * XFACE_HEIGHT) |
| |
| /* compressed output uses the full range of printable characters. |
| * In ASCII these are in a contiguous block so we just need to know |
| * the first and last. The total number of printables is needed too. */ |
| #define XFACE_FIRST_PRINT '!' |
| #define XFACE_LAST_PRINT '~' |
| #define XFACE_PRINTS (XFACE_LAST_PRINT - XFACE_FIRST_PRINT + 1) |
| |
| /* |
| * Image is encoded as a big integer, using characters from '~' to |
| * '!', for a total of 94 symbols. In order to express |
| * 48x48 pixels with the worst case encoding 666 symbols should |
| * be sufficient. |
| */ |
| #define XFACE_MAX_DIGITS 666 |
| |
| #define XFACE_BITSPERWORD 8 |
| #define XFACE_WORDCARRY (1 << XFACE_BITSPERWORD) |
| #define XFACE_WORDMASK (XFACE_WORDCARRY - 1) |
| |
| // This must be larger or equal to log256(94^XFACE_MAX_DIGITS) |
| #define XFACE_MAX_WORDS 546 |
| |
| /* Portable, very large unsigned integer arithmetic is needed. |
| * Implementation uses arrays of WORDs. */ |
| typedef struct { |
| int nb_words; |
| uint8_t words[XFACE_MAX_WORDS]; |
| } BigInt; |
| |
| /** |
| * Add a to b storing the result in b. |
| */ |
| void ff_big_add(BigInt *b, uint8_t a); |
| |
| /** |
| * Divide b by a storing the result in b and the remainder in the word |
| * pointed to by r. |
| */ |
| void ff_big_div(BigInt *b, uint8_t a, uint8_t *r); |
| |
| /** |
| * Multiply a by b storing the result in b. |
| */ |
| void ff_big_mul(BigInt *b, uint8_t a); |
| |
| /* Each face is encoded using 9 octrees of 16x16 each. Each level of the |
| * trees has varying probabilities of being white, grey or black. |
| * The table below is based on sampling many faces */ |
| enum XFaceColor { XFACE_COLOR_BLACK = 0, XFACE_COLOR_GREY, XFACE_COLOR_WHITE }; |
| |
| /* Data of varying probabilities are encoded by a value in the range 0 - 255. |
| * The probability of the data determines the range of possible encodings. |
| * Offset gives the first possible encoding of the range. */ |
| typedef struct { |
| uint8_t range; |
| uint8_t offset; |
| } ProbRange; |
| |
| extern const ProbRange ff_xface_probranges_per_level[4][3]; |
| |
| extern const ProbRange ff_xface_probranges_2x2[16]; |
| |
| void ff_xface_generate_face(uint8_t *dst, uint8_t * const src); |