lavfi/idet: support named parameters.

The parameters are currently not documented in doc/filters.texi, but now
they at least appear in the automatic help.

libavfilter/vf_idet.c

@@ -18,8 +18,11 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include <float.h> /* FLT_MAX */
+
 #include "libavutil/cpu.h"
 #include "libavutil/common.h"
+#include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "avfilter.h"
 #include "internal.h"
@@ -37,6 +40,7 @@ typedef enum {
 } Type;
 
 typedef struct {
+    const AVClass *class;
     float interlace_threshold;
     float progressive_threshold;
 
@@ -54,6 +58,17 @@ typedef struct {
     const AVPixFmtDescriptor *csp;
 } IDETContext;
 
+#define OFFSET(x) offsetof(IDETContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
+
+static const AVOption idet_options[] = {
+    { "intl_thres", "set interlacing threshold", OFFSET(interlace_threshold),   AV_OPT_TYPE_FLOAT, {.dbl = 1.01}, -1, FLT_MAX, FLAGS },
+    { "prog_thres", "set progressive threshold", OFFSET(progressive_threshold), AV_OPT_TYPE_FLOAT, {.dbl = 2.5},  -1, FLT_MAX, FLAGS },
+    { NULL }
+};
+
+AVFILTER_DEFINE_CLASS(idet);
+
 static const char *type2str(Type type)
 {
     switch(type) {
@@ -262,13 +277,15 @@ static int query_formats(AVFilterContext *ctx)
 static av_cold int init(AVFilterContext *ctx, const char *args)
 {
     IDETContext *idet = ctx->priv;
+    static const char *shorthand[] = { "intl_thres", "prog_thres", NULL };
+    int ret;
 
     idet->csp = NULL;
+    idet->class = &idet_class;
+    av_opt_set_defaults(idet);
 
-    idet->interlace_threshold   = 1.01;
-    idet->progressive_threshold = 2.5;
-
-    if (args) sscanf(args, "%f:%f", &idet->interlace_threshold, &idet->progressive_threshold);
+    if ((ret = av_opt_set_from_string(idet, args, shorthand, "=", ":")) < 0)
+        return ret;
 
     idet->last_type = UNDETERMINED;
     memset(idet->history, UNDETERMINED, HIST_SIZE);
@@ -309,4 +326,5 @@ AVFilter avfilter_vf_idet = {
     .query_formats = query_formats,
     .inputs        = idet_inputs,
     .outputs       = idet_outputs,
+    .priv_class    = &idet_class,
 };