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xface.h
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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 #include <stdint.h>
28 
29 /* define the face size - 48x48x1 */
30 #define XFACE_WIDTH 48
31 #define XFACE_HEIGHT 48
32 #define XFACE_PIXELS (XFACE_WIDTH * XFACE_HEIGHT)
33 
34 /* compressed output uses the full range of printable characters.
35  * In ASCII these are in a contiguous block so we just need to know
36  * the first and last. The total number of printables is needed too. */
37 #define XFACE_FIRST_PRINT '!'
38 #define XFACE_LAST_PRINT '~'
39 #define XFACE_PRINTS (XFACE_LAST_PRINT - XFACE_FIRST_PRINT + 1)
40 
41 /*
42  * Image is encoded as a big integer, using characters from '~' to
43  * '!', for a total of 94 symbols. In order to express
44  * 48x48 pixels with the worst case encoding 666 symbols should
45  * be sufficient.
46  */
47 #define XFACE_MAX_DIGITS 666
48 
49 #define XFACE_BITSPERWORD 8
50 #define XFACE_WORDCARRY (1 << XFACE_BITSPERWORD)
51 #define XFACE_WORDMASK (XFACE_WORDCARRY - 1)
52 
53 // This must be larger or equal to log256(94^XFACE_MAX_DIGITS)
54 #define XFACE_MAX_WORDS 546
55 
56 /* Portable, very large unsigned integer arithmetic is needed.
57  * Implementation uses arrays of WORDs. */
58 typedef struct {
59  int nb_words;
61 } BigInt;
62 
63 /**
64  * Add a to b storing the result in b.
65  */
66 void ff_big_add(BigInt *b, uint8_t a);
67 
68 /**
69  * Divide b by a storing the result in b and the remainder in the word
70  * pointed to by r.
71  */
72 void ff_big_div(BigInt *b, uint8_t a, uint8_t *r);
73 
74 /**
75  * Multiply a by b storing the result in b.
76  */
77 void ff_big_mul(BigInt *b, uint8_t a);
78 
79 /* Each face is encoded using 9 octrees of 16x16 each. Each level of the
80  * trees has varying probabilities of being white, grey or black.
81  * The table below is based on sampling many faces */
83 
84 /* Data of varying probabilities are encoded by a value in the range 0 - 255.
85  * The probability of the data determines the range of possible encodings.
86  * Offset gives the first possible encoding of the range. */
87 typedef struct {
90 } ProbRange;
91 
92 extern const ProbRange ff_xface_probranges_per_level[4][3];
93 
94 extern const ProbRange ff_xface_probranges_2x2[16];
95 
96 void ff_xface_generate_face(uint8_t *dst, uint8_t * const src);
uint8_t offset
Definition: xface.h:89
const char * b
Definition: vf_curves.c:109
void ff_big_add(BigInt *b, uint8_t a)
Add a to b storing the result in b.
Definition: xface.c:31
uint8_t
void ff_xface_generate_face(uint8_t *dst, uint8_t *const src)
Definition: xface.c:286
Definition: xface.h:58
uint8_t range
Definition: xface.h:88
XFaceColor
Definition: xface.h:82
#define XFACE_MAX_WORDS
Definition: xface.h:54
const char * r
Definition: vf_curves.c:107
void ff_big_mul(BigInt *b, uint8_t a)
Multiply a by b storing the result in b.
Definition: xface.c:93
AVS_Value src
Definition: avisynth_c.h:482
void ff_big_div(BigInt *b, uint8_t a, uint8_t *r)
Divide b by a storing the result in b and the remainder in the word pointed to by r...
Definition: xface.c:54
const ProbRange ff_xface_probranges_per_level[4][3]
Definition: xface.c:129
const ProbRange ff_xface_probranges_2x2[16]
Definition: xface.c:137
int nb_words
Definition: xface.h:59