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lavfi/thumbnail: add support for named options.

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This commit is contained in:
Clément Bœsch 2013-03-24 20:32:59 +01:00
parent 3b811bcf67
commit 386dc9a3a8
3 changed files with 36 additions and 17 deletions
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24
doc/filters.texi
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@ -5251,22 +5251,36 @@ Swap U & V plane.
@section thumbnail
Select the most representative frame in a given sequence of consecutive frames.
It accepts as argument the frames batch size to analyze (default @var{N}=100);
in a set of @var{N} frames, the filter will pick one of them, and then handle
the next batch of @var{N} frames until the end.
The filter accepts parameters as a list of @var{key}=@var{value}
pairs, separated by ":". If the key of the first options is omitted,
the arguments are interpreted according to the syntax
thumbnail[=@var{n}].
Since the filter keeps track of the whole frames sequence, a bigger @var{N}
@table @option
@item n
Set the frames batch size to analyze; in a set of @var{n} frames, the filter
will pick one of them, and then handle the next batch of @var{n} frames until
the end. Default is @code{100}.
@end table
Since the filter keeps track of the whole frames sequence, a bigger @var{n}
value will result in a higher memory usage, so a high value is not recommended.
The following example extract one picture each 50 frames:
@subsection Examples
@itemize
@item
Extract one picture each 50 frames:
@example
thumbnail=50
@end example
@item
Complete example of a thumbnail creation with @command{ffmpeg}:
@example
ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
@end example
@end itemize
@section tile

2
libavfilter/version.h
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@ -30,7 +30,7 @@
#define LIBAVFILTER_VERSION_MAJOR 3
#define LIBAVFILTER_VERSION_MINOR 48
#define LIBAVFILTER_VERSION_MICRO 101
#define LIBAVFILTER_VERSION_MICRO 102
#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
LIBAVFILTER_VERSION_MINOR, \

27
libavfilter/vf_thumbnail.c
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@ -27,6 +27,7 @@
* @see http://notbrainsurgery.livejournal.com/29773.html
*/
#include "libavutil/opt.h"
#include "avfilter.h"
#include "internal.h"
@ -38,27 +39,27 @@ struct thumb_frame {
};
typedef struct {
const AVClass *class;
int n; ///< current frame
int n_frames; ///< number of frames for analysis
struct thumb_frame *frames; ///< the n_frames frames
AVRational tb; ///< copy of the input timebase to ease access
} ThumbContext;
#define OFFSET(x) offsetof(ThumbContext, x)
#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption thumbnail_options[] = {
{ "n", "set the frames batch size", OFFSET(n_frames), AV_OPT_TYPE_INT, {.i64=100}, 2, INT_MAX, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(thumbnail);
static av_cold int init(AVFilterContext *ctx, const char *args)
{
ThumbContext *thumb = ctx->priv;
if (!args) {
thumb->n_frames = 100;
} else {
int n = sscanf(args, "%d", &thumb->n_frames);
if (n != 1 || thumb->n_frames < 2) {
thumb->n_frames = 0;
av_log(ctx, AV_LOG_ERROR,
"Invalid number of frames specified (minimum is 2).\n");
return AVERROR(EINVAL);
}
}
thumb->frames = av_calloc(thumb->n_frames, sizeof(*thumb->frames));
if (!thumb->frames) {
av_log(ctx, AV_LOG_ERROR,
@ -226,6 +227,8 @@ static const AVFilterPad thumbnail_outputs[] = {
{ NULL }
};
static const char *const shorthand[] = { "n", NULL };
AVFilter avfilter_vf_thumbnail = {
.name = "thumbnail",
.description = NULL_IF_CONFIG_SMALL("Select the most representative frame in a given sequence of consecutive frames."),
@ -235,4 +238,6 @@ AVFilter avfilter_vf_thumbnail = {
.query_formats = query_formats,
.inputs = thumbnail_inputs,
.outputs = thumbnail_outputs,
.priv_class = &thumbnail_class,
.shorthand = shorthand,
};