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spherical.h
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/*
* Copyright (c) 2016 Vittorio Giovara <[email protected]>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* @ingroup lavu_video_spherical
* Spherical video
*/
#ifndef AVUTIL_SPHERICAL_H
#define AVUTIL_SPHERICAL_H
#include <stddef.h>
#include <stdint.h>
/**
* @defgroup lavu_video_spherical Spherical video mapping
* @ingroup lavu_video
*
* A spherical video file contains surfaces that need to be mapped onto a
* sphere. Depending on how the frame was converted, a different distortion
* transformation or surface recomposition function needs to be applied before
* the video should be mapped and displayed.
* @{
*/
/**
* Projection of the video surface(s) on a sphere.
*/
enum AVSphericalProjection {
/**
* Video represents a sphere mapped on a flat surface using
* equirectangular projection.
*/
AV_SPHERICAL_EQUIRECTANGULAR,
/**
* Video frame is split into 6 faces of a cube, and arranged on a
* 3x2 layout. Faces are oriented upwards for the front, left, right,
* and back faces. The up face is oriented so the top of the face is
* forwards and the down face is oriented so the top of the face is
* to the back.
*/
AV_SPHERICAL_CUBEMAP,
/**
* Video represents a portion of a sphere mapped on a flat surface
* using equirectangular projection. The @ref bounding fields indicate
* the position of the current video in a larger surface.
*/
AV_SPHERICAL_EQUIRECTANGULAR_TILE,
/**
* Video frame displays as a 180 degree equirectangular projection.
*/
AV_SPHERICAL_HALF_EQUIRECTANGULAR,
/**
* Video frame displays on a flat, rectangular 2D surface.
*/
AV_SPHERICAL_RECTILINEAR,
/**
* Fisheye projection (Apple).
* See: https://developer.apple.com/documentation/coremedia/cmprojectiontype/fisheye
*/
AV_SPHERICAL_FISHEYE,
};
/**
* This structure describes how to handle spherical videos, outlining
* information about projection, initial layout, and any other view modifier.
*
* @note The struct must be allocated with av_spherical_alloc() and
* its size is not a part of the public ABI.
*/
typedef struct AVSphericalMapping {
/**
* Projection type.
*/
enum AVSphericalProjection projection;
/**
* @name Initial orientation
* @{
* There fields describe additional rotations applied to the sphere after
* the video frame is mapped onto it. The sphere is rotated around the
* viewer, who remains stationary. The order of transformation is always
* yaw, followed by pitch, and finally by roll.
*
* The coordinate system matches the one defined in OpenGL, where the
* forward vector (z) is coming out of screen, and it is equivalent to
* a rotation matrix of R = r_y(yaw) * r_x(pitch) * r_z(roll).
*
* A positive yaw rotates the portion of the sphere in front of the viewer
* toward their right. A positive pitch rotates the portion of the sphere
* in front of the viewer upwards. A positive roll tilts the portion of
* the sphere in front of the viewer to the viewer's right.
*
* These values are exported as 16.16 fixed point.
*
* See this equirectangular projection as example:
*
* @code{.unparsed}
* Yaw
* -180 0 180
* 90 +-------------+-------------+ 180
* | | | up
* P | | | y| forward
* i | ^ | | /z
* t 0 +-------------X-------------+ 0 Roll | /
* c | | | | /
* h | | | 0|/_____right
* | | | x
* -90 +-------------+-------------+ -180
*
* X - the default camera center
* ^ - the default up vector
* @endcode
*/
int32_t yaw; ///< Rotation around the up vector [-180, 180].
int32_t pitch; ///< Rotation around the right vector [-90, 90].
int32_t roll; ///< Rotation around the forward vector [-180, 180].
/**
* @}
*/
/**
* @name Bounding rectangle
* @anchor bounding
* @{
* These fields indicate the location of the current tile, and where
* it should be mapped relative to the original surface. They are
* exported as 0.32 fixed point, and can be converted to classic
* pixel values with av_spherical_bounds().
*
* @code{.unparsed}
* +----------------+----------+
* | |bound_top |
* | +--------+ |
* | bound_left |tile | |
* +<---------->| |<--->+bound_right
* | +--------+ |
* | | |
* | bound_bottom| |
* +----------------+----------+
* @endcode
*
* If needed, the original video surface dimensions can be derived
* by adding the current stream or frame size to the related bounds,
* like in the following example:
*
* @code{c}
* original_width = tile->width + bound_left + bound_right;
* original_height = tile->height + bound_top + bound_bottom;
* @endcode
*
* @note These values are valid only for the tiled equirectangular
* projection type (@ref AV_SPHERICAL_EQUIRECTANGULAR_TILE),
* and should be ignored in all other cases.
*/
uint32_t bound_left; ///< Distance from the left edge
uint32_t bound_top; ///< Distance from the top edge
uint32_t bound_right; ///< Distance from the right edge
uint32_t bound_bottom; ///< Distance from the bottom edge
/**
* @}
*/
/**
* Number of pixels to pad from the edge of each cube face.
*
* @note This value is valid for only for the cubemap projection type
* (@ref AV_SPHERICAL_CUBEMAP), and should be ignored in all other
* cases.
*/
uint32_t padding;
} AVSphericalMapping;
/**
* Allocate a AVSphericalVideo structure and initialize its fields to default
* values.
*
* @return the newly allocated struct or NULL on failure
*/
AVSphericalMapping *av_spherical_alloc(size_t *size);
/**
* Convert the @ref bounding fields from an AVSphericalVideo
* from 0.32 fixed point to pixels.
*
* @param map The AVSphericalVideo map to read bound values from.
* @param width Width of the current frame or stream.
* @param height Height of the current frame or stream.
* @param left Pixels from the left edge.
* @param top Pixels from the top edge.
* @param right Pixels from the right edge.
* @param bottom Pixels from the bottom edge.
*/
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);
/**
* Provide a human-readable name of a given AVSphericalProjection.
*
* @param projection The input AVSphericalProjection.
*
* @return The name of the AVSphericalProjection, or "unknown".
*/
const char *av_spherical_projection_name(enum AVSphericalProjection projection);
/**
* Get the AVSphericalProjection form a human-readable name.
*
* @param name The input string.
*
* @return The AVSphericalProjection value, or -1 if not found.
*/
int av_spherical_from_name(const char *name);
/**
* @}
*/
#endif /* AVUTIL_SPHERICAL_H */