FFmpeg 5.1.6
spherical.h
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1/*
2 * Copyright (c) 2016 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 * Spherical video
24 */
25
26#ifndef AVUTIL_SPHERICAL_H
27#define AVUTIL_SPHERICAL_H
28
29#include <stddef.h>
30#include <stdint.h>
31
32/**
33 * @addtogroup lavu_video
34 * @{
35 *
36 * @defgroup lavu_video_spherical Spherical video mapping
37 * @{
38 */
39
40/**
41 * @addtogroup lavu_video_spherical
42 * A spherical video file contains surfaces that need to be mapped onto a
43 * sphere. Depending on how the frame was converted, a different distortion
44 * transformation or surface recomposition function needs to be applied before
45 * the video should be mapped and displayed.
46 */
47
48/**
49 * Projection of the video surface(s) on a sphere.
50 */
52 /**
53 * Video represents a sphere mapped on a flat surface using
54 * equirectangular projection.
55 */
57
58 /**
59 * Video frame is split into 6 faces of a cube, and arranged on a
60 * 3x2 layout. Faces are oriented upwards for the front, left, right,
61 * and back faces. The up face is oriented so the top of the face is
62 * forwards and the down face is oriented so the top of the face is
63 * to the back.
64 */
66
67 /**
68 * Video represents a portion of a sphere mapped on a flat surface
69 * using equirectangular projection. The @ref bounding fields indicate
70 * the position of the current video in a larger surface.
71 */
73};
74
75/**
76 * This structure describes how to handle spherical videos, outlining
77 * information about projection, initial layout, and any other view modifier.
78 *
79 * @note The struct must be allocated with av_spherical_alloc() and
80 * its size is not a part of the public ABI.
81 */
82typedef struct AVSphericalMapping {
83 /**
84 * Projection type.
85 */
87
88 /**
89 * @name Initial orientation
90 * @{
91 * There fields describe additional rotations applied to the sphere after
92 * the video frame is mapped onto it. The sphere is rotated around the
93 * viewer, who remains stationary. The order of transformation is always
94 * yaw, followed by pitch, and finally by roll.
95 *
96 * The coordinate system matches the one defined in OpenGL, where the
97 * forward vector (z) is coming out of screen, and it is equivalent to
98 * a rotation matrix of R = r_y(yaw) * r_x(pitch) * r_z(roll).
99 *
100 * A positive yaw rotates the portion of the sphere in front of the viewer
101 * toward their right. A positive pitch rotates the portion of the sphere
102 * in front of the viewer upwards. A positive roll tilts the portion of
103 * the sphere in front of the viewer to the viewer's right.
104 *
105 * These values are exported as 16.16 fixed point.
106 *
107 * See this equirectangular projection as example:
108 *
109 * @code{.unparsed}
110 * Yaw
111 * -180 0 180
112 * 90 +-------------+-------------+ 180
113 * | | | up
114 * P | | | y| forward
115 * i | ^ | | /z
116 * t 0 +-------------X-------------+ 0 Roll | /
117 * c | | | | /
118 * h | | | 0|/_____right
119 * | | | x
120 * -90 +-------------+-------------+ -180
121 *
122 * X - the default camera center
123 * ^ - the default up vector
124 * @endcode
125 */
126 int32_t yaw; ///< Rotation around the up vector [-180, 180].
127 int32_t pitch; ///< Rotation around the right vector [-90, 90].
128 int32_t roll; ///< Rotation around the forward vector [-180, 180].
129 /**
130 * @}
131 */
132
133 /**
134 * @name Bounding rectangle
135 * @anchor bounding
136 * @{
137 * These fields indicate the location of the current tile, and where
138 * it should be mapped relative to the original surface. They are
139 * exported as 0.32 fixed point, and can be converted to classic
140 * pixel values with av_spherical_bounds().
141 *
142 * @code{.unparsed}
143 * +----------------+----------+
144 * | |bound_top |
145 * | +--------+ |
146 * | bound_left |tile | |
147 * +<---------->| |<--->+bound_right
148 * | +--------+ |
149 * | | |
150 * | bound_bottom| |
151 * +----------------+----------+
152 * @endcode
153 *
154 * If needed, the original video surface dimensions can be derived
155 * by adding the current stream or frame size to the related bounds,
156 * like in the following example:
157 *
158 * @code{c}
159 * original_width = tile->width + bound_left + bound_right;
160 * original_height = tile->height + bound_top + bound_bottom;
161 * @endcode
162 *
163 * @note These values are valid only for the tiled equirectangular
164 * projection type (@ref AV_SPHERICAL_EQUIRECTANGULAR_TILE),
165 * and should be ignored in all other cases.
166 */
167 uint32_t bound_left; ///< Distance from the left edge
168 uint32_t bound_top; ///< Distance from the top edge
169 uint32_t bound_right; ///< Distance from the right edge
170 uint32_t bound_bottom; ///< Distance from the bottom edge
171 /**
172 * @}
173 */
174
175 /**
176 * Number of pixels to pad from the edge of each cube face.
177 *
178 * @note This value is valid for only for the cubemap projection type
179 * (@ref AV_SPHERICAL_CUBEMAP), and should be ignored in all other
180 * cases.
181 */
182 uint32_t padding;
184
185/**
186 * Allocate a AVSphericalVideo structure and initialize its fields to default
187 * values.
188 *
189 * @return the newly allocated struct or NULL on failure
190 */
192
193/**
194 * Convert the @ref bounding fields from an AVSphericalVideo
195 * from 0.32 fixed point to pixels.
196 *
197 * @param map The AVSphericalVideo map to read bound values from.
198 * @param width Width of the current frame or stream.
199 * @param height Height of the current frame or stream.
200 * @param left Pixels from the left edge.
201 * @param top Pixels from the top edge.
202 * @param right Pixels from the right edge.
203 * @param bottom Pixels from the bottom edge.
204 */
206 size_t width, size_t height,
207 size_t *left, size_t *top,
208 size_t *right, size_t *bottom);
209
210/**
211 * Provide a human-readable name of a given AVSphericalProjection.
212 *
213 * @param projection The input AVSphericalProjection.
214 *
215 * @return The name of the AVSphericalProjection, or "unknown".
216 */
218
219/**
220 * Get the AVSphericalProjection form a human-readable name.
221 *
222 * @param name The input string.
223 *
224 * @return The AVSphericalProjection value, or -1 if not found.
225 */
226int av_spherical_from_name(const char *name);
227/**
228 * @}
229 * @}
230 */
231
232#endif /* AVUTIL_SPHERICAL_H */
static int width
static int height
AVSphericalMapping * av_spherical_alloc(size_t *size)
Allocate a AVSphericalVideo structure and initialize its fields to default values.
int av_spherical_from_name(const char *name)
Get the AVSphericalProjection form a human-readable name.
AVSphericalProjection
Projection of the video surface(s) on a sphere.
Definition: spherical.h:51
const char * av_spherical_projection_name(enum AVSphericalProjection projection)
Provide a human-readable name of a given AVSphericalProjection.
void av_spherical_tile_bounds(const AVSphericalMapping *map, size_t width, size_t height, size_t *left, size_t *top, size_t *right, size_t *bottom)
Convert the bounding fields from an AVSphericalVideo from 0.32 fixed point to pixels.
@ AV_SPHERICAL_EQUIRECTANGULAR
Video represents a sphere mapped on a flat surface using equirectangular projection.
Definition: spherical.h:56
@ AV_SPHERICAL_EQUIRECTANGULAR_TILE
Video represents a portion of a sphere mapped on a flat surface using equirectangular projection.
Definition: spherical.h:72
@ AV_SPHERICAL_CUBEMAP
Video frame is split into 6 faces of a cube, and arranged on a 3x2 layout.
Definition: spherical.h:65
This structure describes how to handle spherical videos, outlining information about projection,...
Definition: spherical.h:82
uint32_t bound_left
Distance from the left edge.
Definition: spherical.h:167
enum AVSphericalProjection projection
Projection type.
Definition: spherical.h:86
uint32_t bound_top
Distance from the top edge.
Definition: spherical.h:168
uint32_t bound_bottom
Distance from the bottom edge.
Definition: spherical.h:170
uint32_t bound_right
Distance from the right edge.
Definition: spherical.h:169
int32_t pitch
Rotation around the right vector [-90, 90].
Definition: spherical.h:127
int32_t roll
Rotation around the forward vector [-180, 180].
Definition: spherical.h:128
int32_t yaw
Rotation around the up vector [-180, 180].
Definition: spherical.h:126
uint32_t padding
Number of pixels to pad from the edge of each cube face.
Definition: spherical.h:182