On Tue, Dec 6, 2016 at 10:44 AM, Vittorio Giovara
<[email protected]> wrote:
> While no decoder currently exports spherical information, this type
> represents a frame property that has to be passed through from container
> to frames.
>
> Signed-off-by: Vittorio Giovara <[email protected]>
> ---
> The specification got updated while this was in the works. So I updated
> the description of yaw, pitch, roll and added a paragraph about the
> coordinate system.
> Vittorio
>
> doc/APIchanges | 4 ++
> libavutil/Makefile | 2 +
> libavutil/frame.h | 6 +++
> libavutil/spherical.c | 34 +++++++++++++
> libavutil/spherical.h | 136
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 182 insertions(+)
> create mode 100644 libavutil/spherical.c
> create mode 100644 libavutil/spherical.h
>
> diff --git a/doc/APIchanges b/doc/APIchanges
> index dfd1532..01ac90d 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -13,6 +13,10 @@ libavutil: 2015-08-28
>
> API changes, most recent first:
>
> +2016-xx-xx - xxxxxxx - lavu 55.29.0 - spherical.h
> + Add AV_FRAME_DATA_SPHERICAL value, av_spherical_alloc() API and
> + AVSphericalMapping type to export and describe spherical video properties.
> +
> 2016-xx-xx - xxxxxxx - lavf 57.10.0 - avformat.h
> Add av_stream_add_side_data().
>
> diff --git a/libavutil/Makefile b/libavutil/Makefile
> index fbcf1a7..28372c9 100644
> --- a/libavutil/Makefile
> +++ b/libavutil/Makefile
> @@ -48,6 +48,7 @@ HEADERS = adler32.h
> \
> replaygain.h \
> samplefmt.h \
> sha.h \
> + spherical.h \
> stereo3d.h \
> time.h \
> version.h \
> @@ -102,6 +103,7 @@ OBJS = adler32.o
> \
> rc4.o \
> samplefmt.o \
> sha.o \
> + spherical.o \
> stereo3d.o \
> time.o \
> tree.o \
> diff --git a/libavutil/frame.h b/libavutil/frame.h
> index 12624d7..4052199 100644
> --- a/libavutil/frame.h
> +++ b/libavutil/frame.h
> @@ -92,6 +92,12 @@ enum AVFrameSideDataType {
> * enum AVAudioServiceType defined in avcodec.h.
> */
> AV_FRAME_DATA_AUDIO_SERVICE_TYPE,
> +
> + /**
> + * The data represents the AVSphericalMapping structure defined in
> + * libavutil/spherical.h.
> + */
> + AV_FRAME_DATA_SPHERICAL,
> };
>
> enum AVActiveFormatDescription {
> diff --git a/libavutil/spherical.c b/libavutil/spherical.c
> new file mode 100644
> index 0000000..f6e53d1
> --- /dev/null
> +++ b/libavutil/spherical.c
> @@ -0,0 +1,34 @@
> +/*
> + * Copyright (c) 2016 Vittorio Giovara <[email protected]>
> + *
> + * This file is part of Libav.
> + *
> + * Libav 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.
> + *
> + * Libav 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 Libav; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
> USA
> + */
> +
> +#include "mem.h"
> +#include "spherical.h"
> +
> +AVSphericalMapping *av_spherical_alloc(size_t *size)
> +{
> + AVSphericalMapping *spherical = av_mallocz(sizeof(AVSphericalMapping));
> + if (!spherical)
> + return NULL;
> +
> + if (size)
> + *size = sizeof(*spherical);
> +
> + return spherical;
> +}
> diff --git a/libavutil/spherical.h b/libavutil/spherical.h
> new file mode 100644
> index 0000000..b37842e
> --- /dev/null
> +++ b/libavutil/spherical.h
> @@ -0,0 +1,136 @@
> +/*
> + * Copyright (c) 2016 Vittorio Giovara <[email protected]>
> + *
> + * This file is part of Libav.
> + *
> + * Libav 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.
> + *
> + * Libav 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 Libav; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
> USA
> + */
> +
> +/**
> + * @file
> + * Spherical video
> + */
> +
> +#ifndef AVUTIL_SPHERICAL_H
> +#define AVUTIL_SPHERICAL_H
> +
> +/**
> + * @addtogroup lavu_video
> + * @{
> + *
> + * @defgroup lavu_video_spherical Spherical video mapping
> + * @{
> + */
> +
> +/**
> + * @addtogroup lavu_video_spherical
> + * 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,
> +};
> +
> +/**
> + * 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 points the viewer towards the left.
> + * A positive pitch points the viewer downwards.
> + * A positive roll tilts the viewer to the right.
One more version, hopefully final
* 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.
Unless objections, I'll push this version of the set in the next few days.
--
Vittorio
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