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77 lines
2.8 KiB
77 lines
2.8 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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#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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* The angle will be in range [-180.0, 180.0], or NaN if the matrix is |
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* 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 rotation by the |
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* 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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#endif /* AVUTIL_DISPLAY_H */
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