vf_cropdetect: switch to an AVOptions-based system.

doc/filters.texi

@@ -742,10 +742,7 @@ Calculate necessary cropping parameters and prints the recommended
 parameters through the logging system. The detected dimensions
 correspond to the non-black area of the input video.
 
-It accepts the syntax:
-@example
-cropdetect[=@var{limit}[:@var{round}[:@var{reset}]]]
-@end example
+This filter accepts the following options:
 
 @table @option
 

libavfilter/vf_cropdetect.c

@@ -27,12 +27,15 @@
 
 #include "libavutil/imgutils.h"
 #include "libavutil/internal.h"
+#include "libavutil/opt.h"
+
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 
 typedef struct {
+    const AVClass *class;
     int x1, y1, x2, y2;
     int limit;
     int round;
@@ -87,14 +90,8 @@ static av_cold int init(AVFilterContext *ctx, const char *args)
 {
     CropDetectContext *cd = ctx->priv;
 
-    cd->limit = 24;
-    cd->round = 0;
-    cd->reset_count = 0;
     cd->frame_nb = -2;
 
-    if (args)
-        sscanf(args, "%d:%d:%d", &cd->limit, &cd->round, &cd->reset_count);
-
     av_log(ctx, AV_LOG_VERBOSE, "limit:%d round:%d reset_count:%d\n",
            cd->limit, cd->round, cd->reset_count);
 
@@ -196,6 +193,22 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
     return ff_filter_frame(inlink->dst->outputs[0], frame);
 }
 
+#define OFFSET(x) offsetof(CropDetectContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM
+static const AVOption options[] = {
+    { "limit", "Threshold below which the pixel is considered black", OFFSET(limit),       AV_OPT_TYPE_INT, { .i64 = 24 }, 0, INT_MAX, FLAGS },
+    { "round", "Value by which the width/height should be divisible", OFFSET(round),       AV_OPT_TYPE_INT, { .i64 = 0  }, 0, INT_MAX, FLAGS },
+    { "reset", "Recalculate the crop area after this many frames",    OFFSET(reset_count), AV_OPT_TYPE_INT, { .i64 = 0 },  0, INT_MAX, FLAGS },
+    { NULL },
+};
+
+static const AVClass cropdetect_class = {
+    .class_name = "cropdetect",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
 static const AVFilterPad avfilter_vf_cropdetect_inputs[] = {
     {
         .name             = "default",
@@ -220,6 +233,7 @@ AVFilter avfilter_vf_cropdetect = {
     .description = NULL_IF_CONFIG_SMALL("Auto-detect crop size."),
 
     .priv_size = sizeof(CropDetectContext),
+    .priv_class = &cropdetect_class,
     .init      = init,
 
     .query_formats = query_formats,