From bddd8cbf68551f6405b2bf77cc3e212af9fbe834 Mon Sep 17 00:00:00 2001 From: Vittorio Giovara Date: Thu, 15 May 2014 22:06:49 -0400 Subject: Add transformation matrix API. Add AV_PKT_DATA_DISPLAYMATRIX and AV_FRAME_DATA_DISPLAYMATRIX as stream and frame side data (respectively) to describe a display transformation matrix for linear transformation operations on the decoded video. Add functions to easily extract a rotation angle from a matrix and conversely to setup a matrix for a given rotation angle. Signed-off-by: Anton Khirnov --- libavutil/display.h | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+) create mode 100644 libavutil/display.h (limited to 'libavutil/display.h') diff --git a/libavutil/display.h b/libavutil/display.h new file mode 100644 index 0000000000..ea762a4249 --- /dev/null +++ b/libavutil/display.h @@ -0,0 +1,77 @@ +/* + * Copyright (c) 2014 Vittorio Giovara + * + * This file is part of Libav. + * + * Libav is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * Libav is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with Libav; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#ifndef AVUTIL_DISPLAY_H +#define AVUTIL_DISPLAY_H + +#include + +/** + * The display transformation matrix specifies an affine transformation that + * should be applied to video frames for correct presentation. It is compatible + * with the matrices stored in the ISO/IEC 14496-12 container format. + * + * The data is a 3x3 matrix represented as a 9-element array: + * + * | a b u | + * (a, b, u, c, d, v, x, y, w) -> | c d v | + * | x y w | + * + * All numbers are stored in native endianness, as 16.16 fixed-point values, + * except for u, v and w, which are stored as 2.30 fixed-point values. + * + * The transformation maps a point (p, q) in the source (pre-transformation) + * frame to the point (p', q') in the destination (post-transformation) frame as + * follows: + * | a b u | + * (p, q, 1) . | c d v | = z * (p', q', 1) + * | x y w | + * + * The transformation can also be more explicitly written in components as + * follows: + * p' = (a * p + c * q + x) / z; + * q' = (b * p + d * q + y) / z; + * z = u * p + v * q + w + */ + +/** + * Extract the rotation component of the transformation matrix. + * + * @param matrix the transformation matrix + * @return the angle (in degrees) by which the transformation rotates the frame. + * The angle will be in range [-180.0, 180.0], or NaN if the matrix is + * singular. + * + * @note floating point numbers are inherently inexact, so callers are + * recommended to round the return value to nearest integer before use. + */ +double av_display_rotation_get(const int32_t matrix[9]); + +/** + * Initialize a transformation matrix describing a pure rotation by the + * specified angle (in degrees). + * + * @param matrix an allocated transformation matrix (will be fully overwritten + * by this function) + * @param angle rotation angle in degrees. + */ +void av_display_rotation_set(int32_t matrix[9], double angle); + +#endif /* AVUTIL_DISPLAY_H */ -- cgit v1.2.3