transform.c File Reference

transform input video More...

#include "libavutil/common.h"
#include "libavutil/avassert.h"
#include "transform.h"

Macros
#define	INTERPOLATE_METHOD(name)
#define	PIXEL(img, x, y, w, h, stride, def)

Functions
	INTERPOLATE_METHOD (interpolate_nearest)
	Nearest neighbor interpolation.
	INTERPOLATE_METHOD (interpolate_bilinear)
	Bilinear interpolation.
	INTERPOLATE_METHOD (interpolate_biquadratic)
	Biquadratic interpolation.
void	avfilter_get_matrix (float x_shift, float y_shift, float angle, float zoom, float *matrix)
	Get an affine transformation matrix from a given translation, rotation, and zoom factor. More...
void	avfilter_add_matrix (const float *m1, const float *m2, float *result)
	Add two matrices together. More...
void	avfilter_sub_matrix (const float *m1, const float *m2, float *result)
	Subtract one matrix from another. More...
void	avfilter_mul_matrix (const float *m1, float scalar, float *result)
	Multiply a matrix by a scalar value. More...
int	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)
	Do an affine transformation with the given interpolation method. More...

Detailed Description

transform input video

Macro Definition Documentation

INTERPOLATE_METHOD

#define INTERPOLATE_METHOD

(

name

)

Value:

static uint8_t name(float x, float y, const uint8_t *src, \
                        int width, int height, int stride, uint8_t def)

PIXEL

#define PIXEL	(		img,
			x,
			y,
			w,
			h,
			stride,
			def
	)

Value:

((x) < 0 || (y) < 0) ? (def) : \
    (((x) >= (w) || (y) >= (h)) ? (def) : \
    img[(x) + (y) * (stride)])

Function Documentation

avfilter_add_matrix()

void avfilter_add_matrix	(	const float *	m1,
		const float *	m2,
		float *	result
	)

Add two matrices together.

result = m1 + m2.

Parameters

m1	9-item transformation matrix
m2	9-item transformation matrix
result	9-item transformation matrix

avfilter_get_matrix()

void avfilter_get_matrix	(	float	x_shift,
		float	y_shift,
		float	angle,
		float	zoom,
		float *	matrix
	)

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 ]

Parameters

x_shift	horizontal translation
y_shift	vertical translation
angle	rotation in radians
zoom	scale percent (1.0 = 100%)
matrix	9-item affine transformation matrix

avfilter_mul_matrix()

void avfilter_mul_matrix	(	const float *	m1,
		float	scalar,
		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

avfilter_sub_matrix()

void avfilter_sub_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

avfilter_transform()

int 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
	)

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

Returns

negative on error