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e4fe535d12
This will allow to copy the matrix as is and it is just cleaner to keep the matrix in the same order specified by the mov standard (which is also explicitly described in the documentation). In order to preserve compatibility, flip the angle sign in the display API av_display_rotation_set() and av_display_rotation_get(), and improve the documentation mentioning the rotation direction.
87 lines
3.1 KiB
C
87 lines
3.1 KiB
C
/*
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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 Libav.
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*
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* Libav 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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* Libav 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 Libav; 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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#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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* 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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* | 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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*
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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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* | 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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*
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* The transformation can also be more explicitly written in components as
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* follows:
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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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*/
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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 counterclockwise
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* rotation by the specified angle (in degrees).
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*
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* @param matrix an allocated 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 matrix an allocated 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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#endif /* AVUTIL_DISPLAY_H */
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