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1 | /* |
2 | * Copyright (c) 2014 Vittorio Giovara <vittorio.giovara@gmail.com> | |
3 | * | |
4 | * This file is part of FFmpeg. | |
5 | * | |
6 | * FFmpeg is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU Lesser General Public | |
8 | * License as published by the Free Software Foundation; either | |
9 | * version 2.1 of the License, or (at your option) any later version. | |
10 | * | |
11 | * FFmpeg is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * Lesser General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU Lesser General Public | |
17 | * License along with FFmpeg; if not, write to the Free Software | |
18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
19 | */ | |
20 | ||
21 | #ifndef AVUTIL_DISPLAY_H | |
22 | #define AVUTIL_DISPLAY_H | |
23 | ||
24 | #include <stdint.h> | |
25 | ||
26 | /** | |
27 | * The display transformation matrix specifies an affine transformation that | |
28 | * should be applied to video frames for correct presentation. It is compatible | |
29 | * with the matrices stored in the ISO/IEC 14496-12 container format. | |
30 | * | |
31 | * The data is a 3x3 matrix represented as a 9-element array: | |
32 | * | |
33 | * | a b u | | |
34 | * (a, b, u, c, d, v, x, y, w) -> | c d v | | |
35 | * | x y w | | |
36 | * | |
37 | * All numbers are stored in native endianness, as 16.16 fixed-point values, | |
38 | * except for u, v and w, which are stored as 2.30 fixed-point values. | |
39 | * | |
40 | * The transformation maps a point (p, q) in the source (pre-transformation) | |
41 | * frame to the point (p', q') in the destination (post-transformation) frame as | |
42 | * follows: | |
43 | * | a b u | | |
44 | * (p, q, 1) . | c d v | = z * (p', q', 1) | |
45 | * | x y w | | |
46 | * | |
47 | * The transformation can also be more explicitly written in components as | |
48 | * follows: | |
49 | * p' = (a * p + c * q + x) / z; | |
50 | * q' = (b * p + d * q + y) / z; | |
51 | * z = u * p + v * q + w | |
52 | */ | |
53 | ||
54 | /** | |
55 | * Extract the rotation component of the transformation matrix. | |
56 | * | |
57 | * @param matrix the transformation matrix | |
58 | * @return the angle (in degrees) by which the transformation rotates the frame. | |
59 | * The angle will be in range [-180.0, 180.0], or NaN if the matrix is | |
60 | * singular. | |
61 | * | |
62 | * @note floating point numbers are inherently inexact, so callers are | |
63 | * recommended to round the return value to nearest integer before use. | |
64 | */ | |
65 | double av_display_rotation_get(const int32_t matrix[9]); | |
66 | ||
67 | /** | |
68 | * Initialize a transformation matrix describing a pure rotation by the | |
69 | * specified angle (in degrees). | |
70 | * | |
71 | * @param matrix an allocated transformation matrix (will be fully overwritten | |
72 | * by this function) | |
73 | * @param angle rotation angle in degrees. | |
74 | */ | |
75 | void av_display_rotation_set(int32_t matrix[9], double angle); | |
76 | ||
77 | /** | |
78 | * Flip the input matrix horizontally and/or vertically. | |
79 | * | |
80 | * @param matrix an allocated transformation matrix | |
81 | * @param hflip whether the matrix should be flipped horizontally | |
82 | * @param vflip whether the matrix should be flipped vertically | |
83 | */ | |
84 | void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip); | |
85 | ||
86 | #endif /* AVUTIL_DISPLAY_H */ |