mirror of https://git.videolan.org/git/ffmpeg.git
lavfi/thumbnail: add support for named options.
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@ -5251,22 +5251,36 @@ Swap U & V plane.
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@section thumbnail
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Select the most representative frame in a given sequence of consecutive frames.
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It accepts as argument the frames batch size to analyze (default @var{N}=100);
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in a set of @var{N} frames, the filter will pick one of them, and then handle
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the next batch of @var{N} frames until the end.
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The filter accepts parameters as a list of @var{key}=@var{value}
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pairs, separated by ":". If the key of the first options is omitted,
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the arguments are interpreted according to the syntax
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thumbnail[=@var{n}].
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Since the filter keeps track of the whole frames sequence, a bigger @var{N}
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@table @option
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@item n
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Set the frames batch size to analyze; in a set of @var{n} frames, the filter
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will pick one of them, and then handle the next batch of @var{n} frames until
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the end. Default is @code{100}.
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@end table
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Since the filter keeps track of the whole frames sequence, a bigger @var{n}
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value will result in a higher memory usage, so a high value is not recommended.
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The following example extract one picture each 50 frames:
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@subsection Examples
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@itemize
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@item
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Extract one picture each 50 frames:
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@example
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thumbnail=50
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@end example
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@item
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Complete example of a thumbnail creation with @command{ffmpeg}:
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@example
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ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png
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@end example
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@end itemize
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@section tile
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@ -30,7 +30,7 @@
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#define LIBAVFILTER_VERSION_MAJOR 3
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#define LIBAVFILTER_VERSION_MINOR 48
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#define LIBAVFILTER_VERSION_MICRO 101
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#define LIBAVFILTER_VERSION_MICRO 102
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#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
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LIBAVFILTER_VERSION_MINOR, \
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@ -27,6 +27,7 @@
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* @see http://notbrainsurgery.livejournal.com/29773.html
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*/
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#include "libavutil/opt.h"
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#include "avfilter.h"
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#include "internal.h"
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@ -38,27 +39,27 @@ struct thumb_frame {
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};
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typedef struct {
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const AVClass *class;
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int n; ///< current frame
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int n_frames; ///< number of frames for analysis
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struct thumb_frame *frames; ///< the n_frames frames
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AVRational tb; ///< copy of the input timebase to ease access
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} ThumbContext;
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#define OFFSET(x) offsetof(ThumbContext, x)
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#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
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static const AVOption thumbnail_options[] = {
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{ "n", "set the frames batch size", OFFSET(n_frames), AV_OPT_TYPE_INT, {.i64=100}, 2, INT_MAX, FLAGS },
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{ NULL }
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};
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AVFILTER_DEFINE_CLASS(thumbnail);
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static av_cold int init(AVFilterContext *ctx, const char *args)
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{
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ThumbContext *thumb = ctx->priv;
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if (!args) {
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thumb->n_frames = 100;
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} else {
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int n = sscanf(args, "%d", &thumb->n_frames);
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if (n != 1 || thumb->n_frames < 2) {
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thumb->n_frames = 0;
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av_log(ctx, AV_LOG_ERROR,
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"Invalid number of frames specified (minimum is 2).\n");
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return AVERROR(EINVAL);
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}
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}
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thumb->frames = av_calloc(thumb->n_frames, sizeof(*thumb->frames));
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if (!thumb->frames) {
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av_log(ctx, AV_LOG_ERROR,
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@ -226,6 +227,8 @@ static const AVFilterPad thumbnail_outputs[] = {
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{ NULL }
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};
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static const char *const shorthand[] = { "n", NULL };
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AVFilter avfilter_vf_thumbnail = {
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.name = "thumbnail",
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.description = NULL_IF_CONFIG_SMALL("Select the most representative frame in a given sequence of consecutive frames."),
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@ -235,4 +238,6 @@ AVFilter avfilter_vf_thumbnail = {
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.query_formats = query_formats,
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.inputs = thumbnail_inputs,
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.outputs = thumbnail_outputs,
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.priv_class = &thumbnail_class,
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.shorthand = shorthand,
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};
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