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141 lines
4.5 KiB
C
141 lines
4.5 KiB
C
/*
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* Copyright (c) 2016 Vittorio Giovara <vittorio.giovara@gmail.com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* Spherical video
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*/
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#ifndef AVUTIL_SPHERICAL_H
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#define AVUTIL_SPHERICAL_H
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#include <stddef.h>
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#include <stdint.h>
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/**
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* @addtogroup lavu_video
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* @{
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*
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* @defgroup lavu_video_spherical Spherical video mapping
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* @{
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*/
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/**
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* @addtogroup lavu_video_spherical
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* A spherical video file contains surfaces that need to be mapped onto a
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* sphere. Depending on how the frame was converted, a different distortion
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* transformation or surface recomposition function needs to be applied before
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* the video should be mapped and displayed.
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*/
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/**
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* Projection of the video surface(s) on a sphere.
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*/
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enum AVSphericalProjection {
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/**
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* Video represents a sphere mapped on a flat surface using
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* equirectangular projection.
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*/
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AV_SPHERICAL_EQUIRECTANGULAR,
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/**
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* Video frame is split into 6 faces of a cube, and arranged on a
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* 3x2 layout. Faces are oriented upwards for the front, left, right,
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* and back faces. The up face is oriented so the top of the face is
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* forwards and the down face is oriented so the top of the face is
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* to the back.
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*/
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AV_SPHERICAL_CUBEMAP,
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};
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/**
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* This structure describes how to handle spherical videos, outlining
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* information about projection, initial layout, and any other view modifier.
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*
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* @note The struct must be allocated with av_spherical_alloc() and
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* its size is not a part of the public ABI.
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*/
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typedef struct AVSphericalMapping {
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/**
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* Projection type.
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*/
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enum AVSphericalProjection projection;
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/**
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* @name Initial orientation
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* @{
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* There fields describe additional rotations applied to the sphere after
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* the video frame is mapped onto it. The sphere is rotated around the
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* viewer, who remains stationary. The order of transformation is always
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* yaw, followed by pitch, and finally by roll.
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*
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* The coordinate system matches the one defined in OpenGL, where the
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* forward vector (z) is coming out of screen, and it is equivalent to
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* a rotation matrix of R = r_y(yaw) * r_x(pitch) * r_z(roll).
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*
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* A positive yaw rotates the portion of the sphere in front of the viewer
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* toward their right. A positive pitch rotates the portion of the sphere
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* in front of the viewer upwards. A positive roll tilts the portion of
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* the sphere in front of the viewer to the viewer's right.
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*
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* These values are exported as 16.16 fixed point.
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*
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* See this equirectangular projection as example:
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*
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* @code{.unparsed}
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* Yaw
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* -180 0 180
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* 90 +-------------+-------------+ 180
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* | | | up
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* P | | | y| forward
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* i | ^ | | /z
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* t 0 +-------------X-------------+ 0 Roll | /
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* c | | | | /
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* h | | | 0|/_____right
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* | | | x
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* -90 +-------------+-------------+ -180
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*
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* X - the default camera center
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* ^ - the default up vector
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* @endcode
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*/
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int32_t yaw; ///< Rotation around the up vector [-180, 180].
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int32_t pitch; ///< Rotation around the right vector [-90, 90].
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int32_t roll; ///< Rotation around the forward vector [-180, 180].
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/**
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* @}
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*/
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} AVSphericalMapping;
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/**
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* Allocate a AVSphericalVideo structure and initialize its fields to default
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* values.
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*
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* @return the newly allocated struct or NULL on failure
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*/
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AVSphericalMapping *av_spherical_alloc(size_t *size);
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/**
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* @}
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* @}
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*/
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#endif /* AVUTIL_SPHERICAL_H */
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