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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 "libavutil/opt.h"
#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)
 
#define OFFSET(x)   offsetof(ThumbContext, x)
 
#define FLAGS   AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
 

Functions

 AVFILTER_DEFINE_CLASS (thumbnail)
 
static av_cold int init (AVFilterContext *ctx)
 
static double frame_sum_square_err (const int *hist, const double *median)
 Compute Sum-square deviation to estimate "closeness".
 
static AVFrameget_best_frame (AVFilterContext *ctx)
 
static int filter_frame (AVFilterLink *inlink, AVFrame *frame)
 
static av_cold void uninit (AVFilterContext *ctx)
 
static int request_frame (AVFilterLink *link)
 
static int config_props (AVFilterLink *inlink)
 
static int query_formats (AVFilterContext *ctx)
 

Variables

static const AVOption thumbnail_options []
 
static const AVFilterPad thumbnail_inputs []
 
static const AVFilterPad thumbnail_outputs []
 
AVFilter ff_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 34 of file vf_thumbnail.c.

Referenced by frame_sum_square_err(), and get_best_frame().

#define OFFSET (   x)    offsetof(ThumbContext, x)

Definition at line 49 of file vf_thumbnail.c.

Definition at line 50 of file vf_thumbnail.c.

Function Documentation

AVFILTER_DEFINE_CLASS ( thumbnail  )
static av_cold int init ( AVFilterContext ctx)
static

Definition at line 59 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
histcolor distribution histogram
medianaverage color distribution histogram
Returns
sum of squared errors

Definition at line 79 of file vf_thumbnail.c.

Referenced by get_best_frame().

static AVFrame* get_best_frame ( AVFilterContext ctx)
static

Definition at line 91 of file vf_thumbnail.c.

Referenced by filter_frame(), and request_frame().

static int filter_frame ( AVFilterLink inlink,
AVFrame frame 
)
static

Definition at line 131 of file vf_thumbnail.c.

static av_cold void uninit ( AVFilterContext ctx)
static

Definition at line 161 of file vf_thumbnail.c.

static int request_frame ( AVFilterLink link)
static

Definition at line 170 of file vf_thumbnail.c.

static int config_props ( AVFilterLink inlink)
static

Definition at line 191 of file vf_thumbnail.c.

static int query_formats ( AVFilterContext ctx)
static

Definition at line 200 of file vf_thumbnail.c.

Variable Documentation

const AVOption thumbnail_options[]
static
Initial value:
= {
{ "n", "set the frames batch size", OFFSET(n_frames), AV_OPT_TYPE_INT, {.i64=100}, 2, INT_MAX, FLAGS },
{ NULL }
}

Definition at line 52 of file vf_thumbnail.c.

const AVFilterPad thumbnail_inputs[]
static
Initial value:
= {
{
.name = "default",
.config_props = config_props,
.filter_frame = filter_frame,
},
{ NULL }
}

Definition at line 212 of file vf_thumbnail.c.

const AVFilterPad thumbnail_outputs[]
static
Initial value:
= {
{
.name = "default",
.request_frame = request_frame,
},
{ NULL }
}

Definition at line 222 of file vf_thumbnail.c.

AVFilter ff_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,
.priv_class = &thumbnail_class,
}

Definition at line 231 of file vf_thumbnail.c.