vf_deshake.c File Reference

fast deshake / depan video filter More...

#include "avfilter.h"
#include "formats.h"
#include "internal.h"
#include "video.h"
#include "libavutil/common.h"
#include "libavutil/mem.h"
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"
#include "libavutil/qsort.h"
#include "deshake.h"

Macros
#define	OFFSET(x)   offsetof(DeshakeContext, x)
#define	FLAGS   AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
#define	CMP(i, j)

Functions
	AVFILTER_DEFINE_CLASS (deshake)

Variables
AVFilter	ff_vf_deshake

Detailed Description

fast deshake / depan video filter

SAD block-matching motion compensation to fix small changes in horizontal and/or vertical shift. This filter helps remove camera shake from hand-holding a camera, bumping a tripod, moving on a vehicle, etc.

Algorithm:

• For each frame with one previous reference frame
  • For each block in the frame
    • If contrast > threshold then find likely motion vector
  • For all found motion vectors
    • Find most common, store as global motion vector
  • Find most likely rotation angle
  • Transform image along global motion

TODO:

• Fill frame edges based on previous/next reference frames
• Fill frame edges by stretching image near the edges?
  • Can this be done quickly and look decent?

Dark Shikari links to http://wiki.videolan.org/SoC_x264_2010#GPU_Motion_Estimation_2 for an algorithm similar to what could be used here to get the gmv It requires only a couple diamond searches + fast downscaling

Special thanks to Jason Kotenko for his help with the algorithm and my inability to see simple errors in C code.

Macro Definition Documentation

CMP

#define CMP	(		i,
			j
	)

Value:

deshake->sad(src1 + cy  * stride + cx,  stride,\
                                   src2 + (j) * stride + (i), stride)

Variable Documentation

ff_vf_deshake

AVFilter ff_vf_deshake

Initial value:

= {
    .name          = "deshake",
    .description   = NULL_IF_CONFIG_SMALL("Stabilize shaky video."),
    .priv_size     = sizeof(DeshakeContext),
    .init          = init,
    .uninit        = uninit,
    .query_formats = query_formats,
    .inputs        = deshake_inputs,
    .outputs       = deshake_outputs,
    .priv_class    = &deshake_class,
}