1 /* 2 * Copyright (c) 2014 Vittorio Giovara <vittorio.giovara@gmail.com> 3 * 4 * This file is part of FFmpeg. 5 * 6 * FFmpeg is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU Lesser General Public 8 * License as published by the Free Software Foundation; either 9 * version 2.1 of the License, or (at your option) any later version. 10 * 11 * FFmpeg is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 * Lesser General Public License for more details. 15 * 16 * You should have received a copy of the GNU Lesser General Public 17 * License along with FFmpeg; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 19 */ 20 21 /** 22 * @file 23 * Display matrix 24 */ 25 26 #ifndef AVUTIL_DISPLAY_H 27 #define AVUTIL_DISPLAY_H 28 29 #include <stdint.h> 30 #include "common.h" 31 32 /** 33 * @addtogroup lavu_video 34 * @{ 35 * 36 * @defgroup lavu_video_display Display transformation matrix functions 37 * @{ 38 */ 39 40 /** 41 * @addtogroup lavu_video_display 42 * The display transformation matrix specifies an affine transformation that 43 * should be applied to video frames for correct presentation. It is compatible 44 * with the matrices stored in the ISO/IEC 14496-12 container format. 45 * 46 * The data is a 3x3 matrix represented as a 9-element array: 47 * 48 * @code{.unparsed} 49 * | a b u | 50 * (a, b, u, c, d, v, x, y, w) -> | c d v | 51 * | x y w | 52 * @endcode 53 * 54 * All numbers are stored in native endianness, as 16.16 fixed-point values, 55 * except for u, v and w, which are stored as 2.30 fixed-point values. 56 * 57 * The transformation maps a point (p, q) in the source (pre-transformation) 58 * frame to the point (p', q') in the destination (post-transformation) frame as 59 * follows: 60 * 61 * @code{.unparsed} 62 * | a b u | 63 * (p, q, 1) . | c d v | = z * (p', q', 1) 64 * | x y w | 65 * @endcode 66 * 67 * The transformation can also be more explicitly written in components as 68 * follows: 69 * 70 * @code{.unparsed} 71 * p' = (a * p + c * q + x) / z; 72 * q' = (b * p + d * q + y) / z; 73 * z = u * p + v * q + w 74 * @endcode 75 */ 76 77 /** 78 * Extract the rotation component of the transformation matrix. 79 * 80 * @param matrix the transformation matrix 81 * @return the angle (in degrees) by which the transformation rotates the frame 82 * counterclockwise. The angle will be in range [-180.0, 180.0], 83 * or NaN if the matrix is singular. 84 * 85 * @note floating point numbers are inherently inexact, so callers are 86 * recommended to round the return value to nearest integer before use. 87 */ 88 double av_display_rotation_get(const int32_t matrix[9]); 89 90 /** 91 * Initialize a transformation matrix describing a pure counterclockwise 92 * rotation by the specified angle (in degrees). 93 * 94 * @param matrix an allocated transformation matrix (will be fully overwritten 95 * by this function) 96 * @param angle rotation angle in degrees. 97 */ 98 void av_display_rotation_set(int32_t matrix[9], double angle); 99 100 /** 101 * Flip the input matrix horizontally and/or vertically. 102 * 103 * @param matrix an allocated transformation matrix 104 * @param hflip whether the matrix should be flipped horizontally 105 * @param vflip whether the matrix should be flipped vertically 106 */ 107 void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip); 108 109 /** 110 * @} 111 * @} 112 */ 113 114 #endif /* AVUTIL_DISPLAY_H */ 115