lavfi: add avfilter_pad_get_type() and avfilter_pad_get_name().

This will allow making AVFilterPad opaque for the calling apps, since
those are the only two fields that can be useful to the users.

libavfilter/avfilter.c

@@ -429,6 +429,16 @@ int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque
     return ret;
 }
 
+const char *avfilter_pad_get_name(AVFilterPad *pads, int pad_idx)
+{
+    return pads[pad_idx].name;
+}
+
+enum AVMediaType avfilter_pad_get_type(AVFilterPad *pads, int pad_idx)
+{
+    return pads[pad_idx].type;
+}
+
 #if FF_API_DEFAULT_CONFIG_OUTPUT_LINK
 int avfilter_default_config_output_link(AVFilterLink *link)
 {

libavfilter/avfilter.h

@@ -359,6 +359,28 @@ struct AVFilterPad {
     int (*config_props)(AVFilterLink *link);
 };
 
+/**
+ * Get the name of an AVFilterPad.
+ *
+ * @param pads an array of AVFilterPads
+ * @param pad_idx index of the pad in the array it; is the caller's
+ *                responsibility to ensure the index is valid
+ *
+ * @return name of the pad_idx'th pad in pads
+ */
+const char *avfilter_pad_get_name(AVFilterPad *pads, int pad_idx);
+
+/**
+ * Get the type of an AVFilterPad.
+ *
+ * @param pads an array of AVFilterPads
+ * @param pad_idx index of the pad in the array; it is the caller's
+ *                responsibility to ensure the index is valid
+ *
+ * @return type of the pad_idx'th pad in pads
+ */
+enum AVMediaType avfilter_pad_get_type(AVFilterPad *pads, int pad_idx);
+
 #if FF_API_FILTERS_PUBLIC
 /** default handler for start_frame() for video inputs */
 attribute_deprecated

libavfilter/version.h

@@ -29,7 +29,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  2
-#define LIBAVFILTER_VERSION_MINOR  21
+#define LIBAVFILTER_VERSION_MINOR  22
 #define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \