vf_fieldorder: switch to an AVOptions-based system.

doc/filters.texi

@@ -1037,15 +1037,13 @@ fade=type=in:start_frame=5:nb_frames=20
 
 Transform the field order of the input video.
 
-It accepts one parameter which specifies the required field order that
-the input interlaced video will be transformed to. The parameter can
-assume one of the following values:
+This filter accepts the following options:
 
 @table @option
-@item 0 or bff
-output bottom field first
-@item 1 or tff
-output top field first
+
+@item order
+Output field order. Valid values are @var{tff} for top field first or @var{bff}
+for bottom field first.
 @end table
 
 Default value is "tff".
@@ -1063,7 +1061,7 @@ which is bottom field first.
 
 For example:
 @example
-./avconv -i in.vob -vf "fieldorder=bff" out.dv
+./avconv -i in.vob -vf "fieldorder=order=bff" out.dv
 @end example
 
 @section fifo

libavfilter/vf_fieldorder.c

@@ -30,6 +30,7 @@
 
 #include "libavutil/imgutils.h"
 #include "libavutil/internal.h"
+#include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "avfilter.h"
 #include "formats.h"
@@ -38,36 +39,11 @@
 
 typedef struct
 {
-    unsigned int dst_tff;      ///< output bff/tff
+    const AVClass *class;
+    int dst_tff;               ///< output bff/tff
     int          line_size[4]; ///< bytes of pixel data per line for each plane
 } FieldOrderContext;
 
-static av_cold int init(AVFilterContext *ctx, const char *args)
-{
-    FieldOrderContext *fieldorder = ctx->priv;
-
-    const char *tff = "tff";
-    const char *bff = "bff";
-
-    if (!args) {
-        fieldorder->dst_tff = 1;
-    } else if (sscanf(args, "%u", &fieldorder->dst_tff) == 1) {
-        fieldorder->dst_tff = !!fieldorder->dst_tff;
-    } else if (!strcmp(tff, args)) {
-        fieldorder->dst_tff = 1;
-    } else if (!strcmp(bff, args)) {
-        fieldorder->dst_tff = 0;
-    } else {
-        av_log(ctx, AV_LOG_ERROR, "Invalid argument '%s'.\n", args);
-        return AVERROR(EINVAL);
-    }
-
-    av_log(ctx, AV_LOG_VERBOSE, "output field order: %s\n",
-            fieldorder->dst_tff ? tff : bff);
-
-    return 0;
-}
-
 static int query_formats(AVFilterContext *ctx)
 {
     AVFilterFormats  *formats;
@@ -177,6 +153,22 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
     return ff_filter_frame(outlink, frame);
 }
 
+#define OFFSET(x) offsetof(FieldOrderContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM
+static const AVOption options[] = {
+    { "order", "output field order", OFFSET(dst_tff), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, FLAGS, "order" },
+        { "bff", "bottom field first", 0, AV_OPT_TYPE_CONST, { .i64 = 0 }, .unit = "order" },
+        { "tff", "top field first",    0, AV_OPT_TYPE_CONST, { .i64 = 1 }, .unit = "order" },
+    { NULL },
+};
+
+static const AVClass fieldorder_class = {
+    .class_name = "fieldorder",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
 static const AVFilterPad avfilter_vf_fieldorder_inputs[] = {
     {
         .name             = "default",
@@ -200,8 +192,8 @@ static const AVFilterPad avfilter_vf_fieldorder_outputs[] = {
 AVFilter avfilter_vf_fieldorder = {
     .name          = "fieldorder",
     .description   = NULL_IF_CONFIG_SMALL("Set the field order."),
-    .init          = init,
     .priv_size     = sizeof(FieldOrderContext),
+    .priv_class    = &fieldorder_class,
     .query_formats = query_formats,
     .inputs        = avfilter_vf_fieldorder_inputs,
     .outputs       = avfilter_vf_fieldorder_outputs,