blob: 39c15ee6b83d552d47adde831665b7b505c10e93
| 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 |