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 #ifndef AVUTIL_DISPLAY_H 22 #define AVUTIL_DISPLAY_H 23 24 #include <stdint.h> 25 #include "common.h" 26 27 /** 28 * The display transformation matrix specifies an affine transformation that 29 * should be applied to video frames for correct presentation. It is compatible 30 * with the matrices stored in the ISO/IEC 14496-12 container format. 31 * 32 * The data is a 3x3 matrix represented as a 9-element array: 33 * 34 * | a b u | 35 * (a, b, u, c, d, v, x, y, w) -> | c d v | 36 * | x y w | 37 * 38 * All numbers are stored in native endianness, as 16.16 fixed-point values, 39 * except for u, v and w, which are stored as 2.30 fixed-point values. 40 * 41 * The transformation maps a point (p, q) in the source (pre-transformation) 42 * frame to the point (p', q') in the destination (post-transformation) frame as 43 * follows: 44 * | a b u | 45 * (p, q, 1) . | c d v | = z * (p', q', 1) 46 * | x y w | 47 * 48 * The transformation can also be more explicitly written in components as 49 * follows: 50 * p' = (a * p + c * q + x) / z; 51 * q' = (b * p + d * q + y) / z; 52 * z = u * p + v * q + w 53 */ 54 55 /** 56 * Extract the rotation component of the transformation matrix. 57 * 58 * @param matrix the transformation matrix 59 * @return the angle (in degrees) by which the transformation rotates the frame 60 * counterclockwise. The angle will be in range [-180.0, 180.0], 61 * or NaN if the matrix is singular. 62 * 63 * @note floating point numbers are inherently inexact, so callers are 64 * recommended to round the return value to nearest integer before use. 65 */ 66 double av_display_rotation_get(const int32_t matrix[9]); 67 68 /** 69 * Initialize a transformation matrix describing a pure counterclockwise 70 * rotation by the specified angle (in degrees). 71 * 72 * @param matrix an allocated transformation matrix (will be fully overwritten 73 * by this function) 74 * @param angle rotation angle in degrees. 75 */ 76 void av_display_rotation_set(int32_t matrix[9], double angle); 77 78 /** 79 * Flip the input matrix horizontally and/or vertically. 80 * 81 * @param matrix an allocated transformation matrix 82 * @param hflip whether the matrix should be flipped horizontally 83 * @param vflip whether the matrix should be flipped vertically 84 */ 85 void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip); 86 87 #endif /* AVUTIL_DISPLAY_H */ 88