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109 lines
3.4 KiB
109 lines
3.4 KiB
/*
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* Copyright (c) 2014 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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* @ingroup lavu_video_display
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* Display matrix
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*/
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#ifndef AVUTIL_DISPLAY_H
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#define AVUTIL_DISPLAY_H
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#include <stdint.h>
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/**
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* @defgroup lavu_video_display Display transformation matrix functions
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* @ingroup lavu_video
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*
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* The display transformation matrix specifies an affine transformation that
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* should be applied to video frames for correct presentation. It is compatible
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* with the matrices stored in the ISO/IEC 14496-12 container format.
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*
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* The data is a 3x3 matrix represented as a 9-element array:
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*
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* @code{.unparsed}
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* | a b u |
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* (a, b, u, c, d, v, x, y, w) -> | c d v |
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* | x y w |
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* @endcode
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*
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* All numbers are stored in native endianness, as 16.16 fixed-point values,
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* except for u, v and w, which are stored as 2.30 fixed-point values.
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*
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* The transformation maps a point (p, q) in the source (pre-transformation)
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* frame to the point (p', q') in the destination (post-transformation) frame as
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* follows:
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*
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* @code{.unparsed}
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* | a b u |
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* (p, q, 1) . | c d v | = z * (p', q', 1)
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* | x y w |
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* @endcode
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*
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* The transformation can also be more explicitly written in components as
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* follows:
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*
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* @code{.unparsed}
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* p' = (a * p + c * q + x) / z;
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* q' = (b * p + d * q + y) / z;
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* z = u * p + v * q + w
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* @endcode
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*
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* @{
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*/
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/**
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* Extract the rotation component of the transformation matrix.
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*
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* @param matrix the transformation matrix
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* @return the angle (in degrees) by which the transformation rotates the frame
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* counterclockwise. The angle will be in range [-180.0, 180.0],
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* or NaN if the matrix is singular.
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*
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* @note floating point numbers are inherently inexact, so callers are
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* recommended to round the return value to nearest integer before use.
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*/
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double av_display_rotation_get(const int32_t matrix[9]);
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/**
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* Initialize a transformation matrix describing a pure clockwise
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* rotation by the specified angle (in degrees).
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*
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* @param[out] matrix a transformation matrix (will be fully overwritten
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* by this function)
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* @param angle rotation angle in degrees.
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*/
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void av_display_rotation_set(int32_t matrix[9], double angle);
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/**
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* Flip the input matrix horizontally and/or vertically.
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*
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* @param[in,out] matrix a transformation matrix
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* @param hflip whether the matrix should be flipped horizontally
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* @param vflip whether the matrix should be flipped vertically
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*/
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void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip);
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/**
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* @}
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*/
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#endif /* AVUTIL_DISPLAY_H */
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