lavfi: remove AVFilter.init_dict()

Nothing uses it anymore.

All options on all filters can now be set with normal AVOptions
mechanisms, such as av_opt_set*().

libavfilter/avfilter.c

@@ -912,8 +912,6 @@ int avfilter_init_dict(AVFilterContext *ctx, AVDictionary **options)
 
     if (ctx->filter->init)
         ret = ctx->filter->init(ctx);
-    else if (ctx->filter->init_dict)
-        ret = ctx->filter->init_dict(ctx, options);
     if (ret < 0)
         return ret;
 

libavfilter/avfilter.h

@@ -276,19 +276,6 @@ typedef struct AVFilter {
      */
     int (*init)(AVFilterContext *ctx);
 
-    /**
-     * Should be set instead of @ref AVFilter.init "init" by the filters that
-     * want to pass a dictionary of AVOptions to nested contexts that are
-     * allocated during init.
-     *
-     * On return, the options dict should be freed and replaced with one that
-     * contains all the options which could not be processed by this filter (or
-     * with NULL if all the options were processed).
-     *
-     * Otherwise the semantics is the same as for @ref AVFilter.init "init".
-     */
-    int (*init_dict)(AVFilterContext *ctx, AVDictionary **options);
-
     /**
      * Filter uninitialization function.
      *