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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  */
82 typedef 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  */
217 const char *av_spherical_projection_name(enum AVSphericalProjection projection);
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  */
226 int av_spherical_from_name(const char *name);
227 /**
228  * @}
229  * @}
230  */
231 
232 #endif /* AVUTIL_SPHERICAL_H */
int32_t pitch
Rotation around the right vector [-90, 90].
Definition: spherical.h:127
AVSphericalMapping * av_spherical_alloc(size_t *size)
Allocate a AVSphericalVideo structure and initialize its fields to default values.
Definition: spherical.c:24
Video represents a portion of a sphere mapped on a flat surface using equirectangular projection...
Definition: spherical.h:72
Video represents a sphere mapped on a flat surface using equirectangular projection.
Definition: spherical.h:56
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.
Definition: spherical.c:36
#define height
ptrdiff_t size
Definition: opengl_enc.c:101
uint32_t bound_bottom
Distance from the bottom edge.
Definition: spherical.h:170
Video frame is split into 6 faces of a cube, and arranged on a 3x2 layout.
Definition: spherical.h:65
#define width
uint32_t bound_right
Distance from the right edge.
Definition: spherical.h:169
int32_t
int av_spherical_from_name(const char *name)
Get the AVSphericalProjection form a human-readable name.
Definition: spherical.c:68
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
AVSphericalProjection
Projection of the video surface(s) on a sphere.
Definition: spherical.h:51
int32_t roll
Rotation around the forward vector [-180, 180].
Definition: spherical.h:128
const VDPAUPixFmtMap * map
This structure describes how to handle spherical videos, outlining information about projection...
Definition: spherical.h:82
uint32_t bound_top
Distance from the top edge.
Definition: spherical.h:168
enum AVSphericalProjection projection
Projection type.
Definition: spherical.h:86
uint32_t bound_left
Distance from the left edge.
Definition: spherical.h:167
const char * av_spherical_projection_name(enum AVSphericalProjection projection)
Provide a human-readable name of a given AVSphericalProjection.
Definition: spherical.c:60
const char * name
Definition: opengl_enc.c:103