vf_thumbnail.c File Reference

Potential thumbnail lookup filter to reduce the risk of an inappropriate selection (such as a black frame) we could get with an absolute seek. More...

#include "avfilter.h"
#include "internal.h"

Go to the source code of this file.

Data Structures
struct	thumb_frame
struct	ThumbContext

Macros
#define	HIST_SIZE   (3*256)

Functions
static av_cold int	init (AVFilterContext *ctx, const char *args)
static double	frame_sum_square_err (const int *hist, const double *median)
	Compute Sum-square deviation to estimate "closeness".
static int	filter_frame (AVFilterLink *inlink, AVFilterBufferRef *frame)
static av_cold void	uninit (AVFilterContext *ctx)
static int	request_frame (AVFilterLink *link)
static int	poll_frame (AVFilterLink *link)
static int	query_formats (AVFilterContext *ctx)

Variables
static const AVFilterPad	thumbnail_inputs []
static const AVFilterPad	thumbnail_outputs []
AVFilter	avfilter_vf_thumbnail

Detailed Description

Potential thumbnail lookup filter to reduce the risk of an inappropriate selection (such as a black frame) we could get with an absolute seek.

Simplified version of algorithm by Vadim Zaliva lord@.nosp@m.croc.nosp@m.odile.nosp@m..org.

See Also

http://notbrainsurgery.livejournal.com/29773.html

Definition in file vf_thumbnail.c.

Macro Definition Documentation

#define HIST_SIZE   (3*256)

Definition at line 33 of file vf_thumbnail.c.

Referenced by filter_frame(), and frame_sum_square_err().

Function Documentation

static av_cold int init ( AVFilterContext *  ctx, const char *  args  )

static

Definition at line 46 of file vf_thumbnail.c.

static double frame_sum_square_err ( const int *  hist, const double *  median  )

static

Compute Sum-square deviation to estimate "closeness".

Parameters

hist	color distribution histogram
median	average color distribution histogram

Returns

sum of squared errors

Definition at line 77 of file vf_thumbnail.c.

Referenced by filter_frame().

static int filter_frame ( AVFilterLink *  inlink, AVFilterBufferRef *  frame  )

static

Definition at line 89 of file vf_thumbnail.c.

static av_cold void uninit ( AVFilterContext *  ctx )

static

Definition at line 150 of file vf_thumbnail.c.

static int request_frame ( AVFilterLink *  link )

static

Definition at line 159 of file vf_thumbnail.c.

static int poll_frame ( AVFilterLink *  link )

static

Definition at line 173 of file vf_thumbnail.c.

static int query_formats ( AVFilterContext *  ctx )

static

Definition at line 195 of file vf_thumbnail.c.

Variable Documentation

const AVFilterPad thumbnail_inputs[]

static

Initial value:

= {
    {
        .name             = "default",
        .type             = AVMEDIA_TYPE_VIDEO,
        .get_video_buffer = ff_null_get_video_buffer,
        .min_perms        = AV_PERM_PRESERVE,
        .filter_frame     = filter_frame,
    },
    { NULL }
}

Definition at line 205 of file vf_thumbnail.c.

const AVFilterPad thumbnail_outputs[]

static

Initial value:

= {
    {
        .name          = "default",
        .type          = AVMEDIA_TYPE_VIDEO,
        .request_frame = request_frame,
        .poll_frame    = poll_frame,
    },
    { NULL }
}

Definition at line 216 of file vf_thumbnail.c.

AVFilter avfilter_vf_thumbnail

Initial value:

= {
    .name          = "thumbnail",
    .description   = NULL_IF_CONFIG_SMALL("Select the most representative frame in a given sequence of consecutive frames."),
    .priv_size     = sizeof(ThumbContext),
    .init          = init,
    .uninit        = uninit,
    .query_formats = query_formats,
    .inputs        = thumbnail_inputs,
    .outputs       = thumbnail_outputs,
}

Definition at line 226 of file vf_thumbnail.c.