FFmpeg/libavfilter/transform.h

/*
 * Copyright (C) 2010 Georg Martius <georg.martius@web.de>
 * Copyright (C) 2010 Daniel G. Taylor <dan@programmer-art.org>
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * transform input video
 *
 * All matrices are defined as a single 9-item block of contiguous memory. For
 * example, the identity matrix would be:
 *
 *     float *matrix = {1, 0, 0,
 *                      0, 1, 0,
 *                      0, 0, 1};
 */

enum InterpolateMethod {
    INTERPOLATE_NEAREST,        //< Nearest-neighbor (fast)
    INTERPOLATE_BILINEAR,       //< Bilinear
    INTERPOLATE_BIQUADRATIC,    //< Biquadratic (best)
    INTERPOLATE_COUNT,          //< Number of interpolation methods
};

// Shortcuts for the fastest and best interpolation methods
#define INTERPOLATE_DEFAULT INTERPOLATE_BILINEAR
#define INTERPOLATE_FAST    INTERPOLATE_NEAREST
#define INTERPOLATE_BEST    INTERPOLATE_BIQUADRATIC

enum FillMethod {
    FILL_BLANK,         //< Fill zeroes at blank locations
    FILL_ORIGINAL,      //< Original image at blank locations
    FILL_CLAMP,         //< Extruded edge value at blank locations
    FILL_MIRROR,        //< Mirrored edge at blank locations
    FILL_COUNT,         //< Number of edge fill methods
};

// Shortcuts for fill methods
#define FILL_DEFAULT FILL_ORIGINAL

/**
 * Get an affine transformation matrix from a given translation, rotation, and
 * zoom factor. The matrix will look like:
 *
 * [ zoom * cos(angle),           -sin(angle),     x_shift,
 *          sin(angle),     zoom * cos(angle),     y_shift,
                     0,                     0,           1 ]
 *
 * Paramters:
 *  x_shift: Horizontal translation
 *  y_shift: Vertical translation
 *    angle: Rotation in radians
 *     zoom: Scale percent (1.0 = 100%)
 *   matrix: 9-item affine transformation matrix
 */
void avfilter_get_matrix(float x_shift, float y_shift, float angle, float zoom, float *matrix);

/**
 * Add two matrices together. result = m1 + m2.
 *
 * Parameters:
 *      m1: 9-item transformation matrix
 *      m2: 9-item transformation matrix
 *  result: 9-item transformation matrix
 */
void avfilter_add_matrix(const float *m1, const float *m2, float *result);

/**
 * Subtract one matrix from another. result = m1 - m2.
 *
 * Parameters:
 *      m1: 9-item transformation matrix
 *      m2: 9-item transformation matrix
 *  result: 9-item transformation matrix
 */
void avfilter_sub_matrix(const float *m1, const float *m2, float *result);

/**
 * Multiply a matrix by a scalar value. result = m1 * scalar.
 *
 * Parameters:
 *      m1: 9-item transformation matrix
 *  scalar: A number
 *  result: 9-item transformation matrix
 */
void avfilter_mul_matrix(const float *m1, float scalar, float *result);

/**
 * Do an affine transformation with the given interpolation method. This
 * multiplies each vector [x,y,1] by the matrix and then interpolates to
 * get the final value.
 *
 * Parameters:
 *          src: Source image
 *          dst: Destination image
 *   src_stride: Source image line size in bytes
 *   dst_stride: Destination image line size in bytes
 *        width: Image width in pixels
 *       height: Image height in pixels
 *       matrix: 9-item affine transformation matrix
 *  interpolate: Pixel interpolation method
 *         fill: Edge fill method
 */
void avfilter_transform(const uint8_t *src, uint8_t *dst,
                        int src_stride, int dst_stride,
                        int width, int height, const float *matrix,
                        enum InterpolateMethod interpolate,
                        enum FillMethod fill);