2 * Copyright (c) 1990 James Ashton - Sydney University
3 * Copyright (c) 2012 Stefano Sabatini
5 * This file is part of FFmpeg.
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.
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.
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
24 * X-Face common definitions.
27 #ifndef AVCODEC_XFACE_H
28 #define AVCODEC_XFACE_H
32 /* define the face size - 48x48x1 */
33 #define XFACE_WIDTH 48
34 #define XFACE_HEIGHT 48
35 #define XFACE_PIXELS (XFACE_WIDTH * XFACE_HEIGHT)
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)
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
50 #define XFACE_MAX_DIGITS 666
52 #define XFACE_BITSPERWORD 8
53 #define XFACE_WORDCARRY (1 << XFACE_BITSPERWORD)
54 #define XFACE_WORDMASK (XFACE_WORDCARRY - 1)
56 // This must be larger or equal to log256(94^XFACE_MAX_DIGITS)
57 #define XFACE_MAX_WORDS 546
59 /* Portable, very large unsigned integer arithmetic is needed.
60 * Implementation uses arrays of WORDs. */
63 uint8_t words[XFACE_MAX_WORDS];
67 * Add a to b storing the result in b.
69 void ff_big_add(BigInt *b, uint8_t a);
72 * Divide b by a storing the result in b and the remainder in the word
75 void ff_big_div(BigInt *b, uint8_t a, uint8_t *r);
78 * Multiply a by b storing the result in b.
80 void ff_big_mul(BigInt *b, uint8_t a);
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 };
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. */
95 extern const ProbRange ff_xface_probranges_per_level[4][3];
97 extern const ProbRange ff_xface_probranges_2x2[16];
99 void ff_xface_generate_face(uint8_t *dst, uint8_t * const src);
101 #endif /* AVCODEC_XFACE_H */