lavfi/ebur128: use ff_filter_frame() everywhere.

libavfilter/f_ebur128.c

@@ -625,9 +625,8 @@ static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *insamples)
 
                 /* set pts and push frame */
                 pic->pts = pts;
-                if ((ret = ff_start_frame(outlink, avfilter_ref_buffer(pic, ~AV_PERM_WRITE))) < 0 ||
-                    (ret = ff_draw_slice(outlink, 0, outlink->h, 1)) < 0 ||
-                    (ret = ff_end_frame(outlink)) < 0)
+                ret = ff_filter_frame(outlink, avfilter_ref_buffer(pic, ~AV_PERM_WRITE));
+                if (ret < 0)
                     return ret;
             }