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