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- /*
- * 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.
- */
- #ifndef AVCODEC_XFACE_H
- #define AVCODEC_XFACE_H
- #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);
- #endif /* AVCODEC_XFACE_H */
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