ffmpeg.libavutil.display source code

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  * Display matrix
24  */
25 module ffmpeg.libavutil.display;
26 extern (C) @nogc nothrow:
27 
28 /**
29  * @addtogroup lavu_video
30  * @{
31  *
32  * @defgroup lavu_video_display Display transformation matrix functions
33  * @{
34  */
35 
36 /**
37  * @addtogroup lavu_video_display
38  * The display transformation matrix specifies an affine transformation that
39  * should be applied to video frames for correct presentation. It is compatible
40  * with the matrices stored in the ISO/IEC 14496-12 container format.
41  *
42  * The data is a 3x3 matrix represented as a 9-element array:
43  *
44  * @code{.unparsed}
45  *                                  | a b u |
46  *   (a, b, u, c, d, v, x, y, w) -> | c d v |
47  *                                  | x y w |
48  * @endcode
49  *
50  * All numbers are stored in native endianness, as 16.16 fixed-point values,
51  * except for u, v and w, which are stored as 2.30 fixed-point values.
52  *
53  * The transformation maps a point (p, q) in the source (pre-transformation)
54  * frame to the point (p', q') in the destination (post-transformation) frame as
55  * follows:
56  *
57  * @code{.unparsed}
58  *               | a b u |
59  *   (p, q, 1) . | c d v | = z * (p', q', 1)
60  *               | x y w |
61  * @endcode
62  *
63  * The transformation can also be more explicitly written in components as
64  * follows:
65  *
66  * @code{.unparsed}
67  *   p' = (a * p + c * q + x) / z;
68  *   q' = (b * p + d * q + y) / z;
69  *   z  =  u * p + v * q + w
70  * @endcode
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  */
84 double av_display_rotation_get (ref const(int)[9] matrix);
85 
86 /**
87  * Initialize a transformation matrix describing a pure counterclockwise
88  * rotation by the specified angle (in degrees).
89  *
90  * @param matrix an allocated transformation matrix (will be fully overwritten
91  *               by this function)
92  * @param angle rotation angle in degrees.
93  */
94 void av_display_rotation_set (ref int[9] matrix, double angle);
95 
96 /**
97  * Flip the input matrix horizontally and/or vertically.
98  *
99  * @param matrix an allocated transformation matrix
100  * @param hflip whether the matrix should be flipped horizontally
101  * @param vflip whether the matrix should be flipped vertically
102  */
103 void av_display_matrix_flip (ref int[9] matrix, int hflip, int vflip);
104 
105 /**
106  * @}
107  * @}
108  */
109 
110 /* AVUTIL_DISPLAY_H */