FFmpeg 6.1.1
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 * @ingroup lavu_video_spherical
24 * Spherical video
25 */
26
27#ifndef AVUTIL_SPHERICAL_H
28#define AVUTIL_SPHERICAL_H
29
30#include <stddef.h>
31#include <stdint.h>
32
33/**
34 * @defgroup lavu_video_spherical Spherical video mapping
35 * @ingroup lavu_video
36 *
37 * A spherical video file contains surfaces that need to be mapped onto a
38 * sphere. Depending on how the frame was converted, a different distortion
39 * transformation or surface recomposition function needs to be applied before
40 * the video should be mapped and displayed.
41 * @{
42 */
43
44/**
45 * Projection of the video surface(s) on a sphere.
46 */
48 /**
49 * Video represents a sphere mapped on a flat surface using
50 * equirectangular projection.
51 */
53
54 /**
55 * Video frame is split into 6 faces of a cube, and arranged on a
56 * 3x2 layout. Faces are oriented upwards for the front, left, right,
57 * and back faces. The up face is oriented so the top of the face is
58 * forwards and the down face is oriented so the top of the face is
59 * to the back.
60 */
62
63 /**
64 * Video represents a portion of a sphere mapped on a flat surface
65 * using equirectangular projection. The @ref bounding fields indicate
66 * the position of the current video in a larger surface.
67 */
69};
70
71/**
72 * This structure describes how to handle spherical videos, outlining
73 * information about projection, initial layout, and any other view modifier.
74 *
75 * @note The struct must be allocated with av_spherical_alloc() and
76 * its size is not a part of the public ABI.
77 */
78typedef struct AVSphericalMapping {
79 /**
80 * Projection type.
81 */
83
84 /**
85 * @name Initial orientation
86 * @{
87 * There fields describe additional rotations applied to the sphere after
88 * the video frame is mapped onto it. The sphere is rotated around the
89 * viewer, who remains stationary. The order of transformation is always
90 * yaw, followed by pitch, and finally by roll.
91 *
92 * The coordinate system matches the one defined in OpenGL, where the
93 * forward vector (z) is coming out of screen, and it is equivalent to
94 * a rotation matrix of R = r_y(yaw) * r_x(pitch) * r_z(roll).
95 *
96 * A positive yaw rotates the portion of the sphere in front of the viewer
97 * toward their right. A positive pitch rotates the portion of the sphere
98 * in front of the viewer upwards. A positive roll tilts the portion of
99 * the sphere in front of the viewer to the viewer's right.
100 *
101 * These values are exported as 16.16 fixed point.
102 *
103 * See this equirectangular projection as example:
104 *
105 * @code{.unparsed}
106 * Yaw
107 * -180 0 180
108 * 90 +-------------+-------------+ 180
109 * | | | up
110 * P | | | y| forward
111 * i | ^ | | /z
112 * t 0 +-------------X-------------+ 0 Roll | /
113 * c | | | | /
114 * h | | | 0|/_____right
115 * | | | x
116 * -90 +-------------+-------------+ -180
117 *
118 * X - the default camera center
119 * ^ - the default up vector
120 * @endcode
121 */
122 int32_t yaw; ///< Rotation around the up vector [-180, 180].
123 int32_t pitch; ///< Rotation around the right vector [-90, 90].
124 int32_t roll; ///< Rotation around the forward vector [-180, 180].
125 /**
126 * @}
127 */
128
129 /**
130 * @name Bounding rectangle
131 * @anchor bounding
132 * @{
133 * These fields indicate the location of the current tile, and where
134 * it should be mapped relative to the original surface. They are
135 * exported as 0.32 fixed point, and can be converted to classic
136 * pixel values with av_spherical_bounds().
137 *
138 * @code{.unparsed}
139 * +----------------+----------+
140 * | |bound_top |
141 * | +--------+ |
142 * | bound_left |tile | |
143 * +<---------->| |<--->+bound_right
144 * | +--------+ |
145 * | | |
146 * | bound_bottom| |
147 * +----------------+----------+
148 * @endcode
149 *
150 * If needed, the original video surface dimensions can be derived
151 * by adding the current stream or frame size to the related bounds,
152 * like in the following example:
153 *
154 * @code{c}
155 * original_width = tile->width + bound_left + bound_right;
156 * original_height = tile->height + bound_top + bound_bottom;
157 * @endcode
158 *
159 * @note These values are valid only for the tiled equirectangular
160 * projection type (@ref AV_SPHERICAL_EQUIRECTANGULAR_TILE),
161 * and should be ignored in all other cases.
162 */
163 uint32_t bound_left; ///< Distance from the left edge
164 uint32_t bound_top; ///< Distance from the top edge
165 uint32_t bound_right; ///< Distance from the right edge
166 uint32_t bound_bottom; ///< Distance from the bottom edge
167 /**
168 * @}
169 */
170
171 /**
172 * Number of pixels to pad from the edge of each cube face.
173 *
174 * @note This value is valid for only for the cubemap projection type
175 * (@ref AV_SPHERICAL_CUBEMAP), and should be ignored in all other
176 * cases.
177 */
178 uint32_t padding;
180
181/**
182 * Allocate a AVSphericalVideo structure and initialize its fields to default
183 * values.
184 *
185 * @return the newly allocated struct or NULL on failure
186 */
188
189/**
190 * Convert the @ref bounding fields from an AVSphericalVideo
191 * from 0.32 fixed point to pixels.
192 *
193 * @param map The AVSphericalVideo map to read bound values from.
194 * @param width Width of the current frame or stream.
195 * @param height Height of the current frame or stream.
196 * @param left Pixels from the left edge.
197 * @param top Pixels from the top edge.
198 * @param right Pixels from the right edge.
199 * @param bottom Pixels from the bottom edge.
200 */
202 size_t width, size_t height,
203 size_t *left, size_t *top,
204 size_t *right, size_t *bottom);
205
206/**
207 * Provide a human-readable name of a given AVSphericalProjection.
208 *
209 * @param projection The input AVSphericalProjection.
210 *
211 * @return The name of the AVSphericalProjection, or "unknown".
212 */
214
215/**
216 * Get the AVSphericalProjection form a human-readable name.
217 *
218 * @param name The input string.
219 *
220 * @return The AVSphericalProjection value, or -1 if not found.
221 */
222int av_spherical_from_name(const char *name);
223/**
224 * @}
225 */
226
227#endif /* AVUTIL_SPHERICAL_H */
static int width
Definition: demux_decode.c:40
static int height
Definition: demux_decode.c:40
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:47
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:52
@ AV_SPHERICAL_EQUIRECTANGULAR_TILE
Video represents a portion of a sphere mapped on a flat surface using equirectangular projection.
Definition: spherical.h:68
@ AV_SPHERICAL_CUBEMAP
Video frame is split into 6 faces of a cube, and arranged on a 3x2 layout.
Definition: spherical.h:61
This structure describes how to handle spherical videos, outlining information about projection,...
Definition: spherical.h:78
uint32_t bound_left
Distance from the left edge.
Definition: spherical.h:163
enum AVSphericalProjection projection
Projection type.
Definition: spherical.h:82
uint32_t bound_top
Distance from the top edge.
Definition: spherical.h:164
uint32_t bound_bottom
Distance from the bottom edge.
Definition: spherical.h:166
uint32_t bound_right
Distance from the right edge.
Definition: spherical.h:165
int32_t pitch
Rotation around the right vector [-90, 90].
Definition: spherical.h:123
int32_t roll
Rotation around the forward vector [-180, 180].
Definition: spherical.h:124
int32_t yaw
Rotation around the up vector [-180, 180].
Definition: spherical.h:122
uint32_t padding
Number of pixels to pad from the edge of each cube face.
Definition: spherical.h:178