vf_overlay: switch to an AVOptions-based system.

doc/filters.texi

@@ -1485,11 +1485,19 @@ Overlay one video on top of another.
 It takes two inputs and one output, the first input is the "main"
 video on which the second input is overlayed.
 
-It accepts the parameters: @var{x}:@var{y}.
+This filter accepts the following parameters:
 
-@var{x} is the x coordinate of the overlayed video on the main video,
+@table @option
-@var{y} is the y coordinate. The parameters are expressions containing
+
-the following parameters:
+@item x
+The horizontal position of the left edge of the overlaid video on the main video.
+
+@item y
+The vertical position of the top edge of the overlaid video on the main video.
+
+@end table
+
+The parameters are expressions containing the following parameters:
 
 @table @option
 @item main_w, main_h
@@ -1515,15 +1523,15 @@ Follow some examples:
 @example
 # draw the overlay at 10 pixels from the bottom right
 # corner of the main video.
-overlay=main_w-overlay_w-10:main_h-overlay_h-10
+overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10
 
 # insert a transparent PNG logo in the bottom left corner of the input
-avconv -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output
+avconv -i input -i logo -filter_complex 'overlay=x=10:y=main_h-overlay_h-10' output
 
 # insert 2 different transparent PNG logos (second logo on bottom
 # right corner):
 avconv -i input -i logo1 -i logo2 -filter_complex
-'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output
+'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output
 
 # add a transparent color layer on top of the main video,
 # WxH specifies the size of the main input to the overlay filter

libavfilter/vf_overlay.c

@@ -34,6 +34,7 @@
 #include "libavutil/pixdesc.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/mathematics.h"
+#include "libavutil/opt.h"
 #include "internal.h"
 #include "video.h"
 
@@ -63,30 +64,18 @@ enum var_name {
 #define OVERLAY 1
 
 typedef struct {
+    const AVClass *class;
     int x, y;                   ///< position of overlayed picture
 
     int max_plane_step[4];      ///< steps per pixel for each plane
     int hsub, vsub;             ///< chroma subsampling values
 
-    char x_expr[256], y_expr[256];
+    char *x_expr, *y_expr;
 
     AVFrame *main;
     AVFrame *over_prev, *over_next;
 } OverlayContext;
 
-static av_cold int init(AVFilterContext *ctx, const char *args)
-{
-    OverlayContext *over = ctx->priv;
-
-    av_strlcpy(over->x_expr, "0", sizeof(over->x_expr));
-    av_strlcpy(over->y_expr, "0", sizeof(over->y_expr));
-
-    if (args)
-        sscanf(args, "%255[^:]:%255[^:]", over->x_expr, over->y_expr);
-
-    return 0;
-}
-
 static av_cold void uninit(AVFilterContext *ctx)
 {
     OverlayContext *s = ctx->priv;
@@ -358,6 +347,23 @@ static int request_frame(AVFilterLink *outlink)
     return output_frame(ctx);
 }
 
+#define OFFSET(x) offsetof(OverlayContext, x)
+#define FLAGS AV_OPT_FLAG_VIDEO_PARAM
+static const AVOption options[] = {
+    { "x", "Horizontal position of the left edge of the overlaid video on the "
+        "main video.",          OFFSET(x_expr), AV_OPT_TYPE_STRING, { .str = "0" }, .flags = FLAGS },
+    { "y", "Vertical position of the top edge of the overlaid video on the "
+        "main video.",          OFFSET(y_expr), AV_OPT_TYPE_STRING, { .str = "0" }, .flags = FLAGS },
+    { NULL },
+};
+
+static const AVClass overlay_class = {
+    .class_name = "overlay",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+};
+
 static const AVFilterPad avfilter_vf_overlay_inputs[] = {
     {
         .name         = "main",
@@ -391,10 +397,10 @@ AVFilter avfilter_vf_overlay = {
     .name      = "overlay",
     .description = NULL_IF_CONFIG_SMALL("Overlay a video source on top of the input."),
 
-    .init      = init,
     .uninit    = uninit,
 
     .priv_size = sizeof(OverlayContext),
+    .priv_class = &overlay_class,
 
     .query_formats = query_formats,