FFmpeg 7.1.1
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display.h
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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/**
22 * @file
23 * @ingroup lavu_video_display
24 * Display matrix
25 */
26
27#ifndef AVUTIL_DISPLAY_H
28#define AVUTIL_DISPLAY_H
29
30#include <stdint.h>
31
32/**
33 * @defgroup lavu_video_display Display transformation matrix functions
34 * @ingroup lavu_video
35 *
36 * The display transformation matrix specifies an affine transformation that
37 * should be applied to video frames for correct presentation. It is compatible
38 * with the matrices stored in the ISO/IEC 14496-12 container format.
39 *
40 * The data is a 3x3 matrix represented as a 9-element array:
41 *
42 * @code{.unparsed}
43 * | a b u |
44 * (a, b, u, c, d, v, x, y, w) -> | c d v |
45 * | x y w |
46 * @endcode
47 *
48 * All numbers are stored in native endianness, as 16.16 fixed-point values,
49 * except for u, v and w, which are stored as 2.30 fixed-point values.
50 *
51 * The transformation maps a point (p, q) in the source (pre-transformation)
52 * frame to the point (p', q') in the destination (post-transformation) frame as
53 * follows:
54 *
55 * @code{.unparsed}
56 * | a b u |
57 * (p, q, 1) . | c d v | = z * (p', q', 1)
58 * | x y w |
59 * @endcode
60 *
61 * The transformation can also be more explicitly written in components as
62 * follows:
63 *
64 * @code{.unparsed}
65 * p' = (a * p + c * q + x) / z;
66 * q' = (b * p + d * q + y) / z;
67 * z = u * p + v * q + w
68 * @endcode
69 *
70 * @{
71 */
72
73/**
74 * Extract the rotation component of the transformation matrix.
75 *
76 * @param matrix the transformation matrix
77 * @return the angle (in degrees) by which the transformation rotates the frame
78 * counterclockwise. The angle will be in range [-180.0, 180.0],
79 * or NaN if the matrix is singular.
80 *
81 * @note floating point numbers are inherently inexact, so callers are
82 * recommended to round the return value to nearest integer before use.
83 */
84double av_display_rotation_get(const int32_t matrix[9]);
85
86/**
87 * Initialize a transformation matrix describing a pure clockwise
88 * rotation by the specified angle (in degrees).
89 *
90 * @param[out] matrix a transformation matrix (will be fully overwritten
91 * by this function)
92 * @param angle rotation angle in degrees.
93 */
94void av_display_rotation_set(int32_t matrix[9], double angle);
95
96/**
97 * Flip the input matrix horizontally and/or vertically.
98 *
99 * @param[in,out] matrix a transformation matrix
100 * @param hflip whether the matrix should be flipped horizontally
101 * @param vflip whether the matrix should be flipped vertically
102 */
103void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip);
104
105/**
106 * @}
107 */
108
109#endif /* AVUTIL_DISPLAY_H */
void av_display_rotation_set(int32_t matrix[9], double angle)
Initialize a transformation matrix describing a pure clockwise rotation by the specified angle (in de...
double av_display_rotation_get(const int32_t matrix[9])
Extract the rotation component of the transformation matrix.
void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip)
Flip the input matrix horizontally and/or vertically.