logo.c File Reference

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdarg.h>
#include <string.h>
#include "common.h"
#include "avformat.h"
#include "avcodec.h"
#include "allformats.h"
#include "framehook.h"
#include "cmdutils.h"

Data Structures
struct	RGBA
struct	RECT
struct	ContextInfo
Defines
#define	MAX_FILEPATH   2048
	Max filepath length.
#define	min(a, b)   ((a < b) ? a : b)
	Return the smaller of 2 values.
#define	max(a, b)   ((a > b) ? a : b)
	Return the larger of 2 values.
Functions
int	Configure (void **ctxp, int argc, char *argv[])
void	Release (void *ctx)
void	Process (void *ctx, AVPicture *picture, enum PixelFormat pix_fmt, int src_width, int src_height, int64_t pts)
int	load_image (ContextInfo *ci)
void	release_image (ContextInfo *ci)
void	calc_bounds (ContextInfo *ci, int vid_width, int vid_height)
int	alpha_merge (int back, int fore, double alpha)

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Detailed Description

Composite an alpha-channel logo with optional drop-shadow onto video.

Sponsored by Fabrik Inc. - bfree(at)fabrikinc.com

Author:

Bob (grafman) Free - bfree(at)graphcomp.com

This vhook demonstrates the use of av_read_image to load still images with alpha/transparency and composite them on video.

Note: PNG support requires that FFMPEG be built with the PNG codec registered/enabled.

EXAMPLE USAGE:

ffmpeg -i INFILE -vhook 'PATH/logo.so -f logo.gif' OUTFILE

Note: the entire vhook argument must be single-quoted.

REQUIRED ARGS:

-f <FILEPATH>

Specifies the image to use for the logo. GIF is supported in normal FFMPEG builds; PNG is supported if enabled in libavcodec and libavformat.

OPTIONAL ARGS:

-x <INT>

Defines a logo offset from the left side of the frame. A negative value (including -0) offsets from the right side.

-y <INT>

Defines a logo offset from the top of the frame. A negative value (including -0) offsets from the bottom.

-w <INT>

Defines a drop shadow to the right of the logo. A negative value shifts the shadow to the left.

-h <INT>

Defines a drop shadow to the bottom of the logo. A negative value shifts the shadow upward.

-d <INT>

Defines the percent opacity of the drop shadow (0 - 100); 100 is opaque. Defaults to 75.

Sample logos and additional notes available at http://graphcomp.com/ffmpeg#plugins

LICENSE:

This library 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 of the License, or (at your option) any later version.

This library 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 this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

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Function Documentation

int alpha_merge	(	int	back,
		int	fore,
		double	alpha
	)

Merges a pixel component onto another using and alpha-channel value.

Parameters:

	back	Background pixel value.
	fore	Foreground pixel value.
	alpha	Alpha-channel value - from 0.0 (transparent) to 1.0 (opaque).

Returns:

Merged component value.

void calc_bounds	(	ContextInfo *	ci,
		int	vid_width,
		int	vid_height
	)

Calculates bounding info for video frame, logo and drop-shadow.

Parameters:

	ci	Context pointer.
	vid_width	Video frame width in pixels.
	vid_height	Video frame height in pixels.

int Configure	(	void **	ctxp,
		int	argc,
		char *	argv[]
	)

Allocate context block and capture user parameters. Called by FFMPEG pipeline.

Parameters:

	ctxp	A handle to receive alloacted context pointer.
	argc	vhook's argument count.
	argv	vhook's argument pointers.

Returns:

0 for success; otherwise failure.

int load_image

(

ContextInfo *

ci

)

Load and cache an image.

Parameters:

ci

Context pointer.

Returns:

0 for success; otherwise failure.

void Process	(	void *	ctx,
		AVPicture *	picture,
		enum PixelFormat	pix_fmt,
		int	src_width,
		int	src_height,
		int64_t	pts
	)

Main video frame proc. Called by FFMPEG pipeline.

Parameters:

	ctx	Context pointer.
	picture	Pointer to video frame.
	pix_fmt	Video frame format constant.
	src_width	Video frame width in pixels.
	src_heigth	Video frame height in pixels.
	pts	Presentation timestamp.

void Release

(

void *

ctx

)

Release context block. Called by FFMPEG pipeline.

Parameters:

ctx

Context pointer.

void release_image

(

ContextInfo *

ci

)

Release an image cache.

Parameters:

ci

Context pointer.

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