Use av_frame_copy() to simplify code where appropriate.

libavcodec/libwebpenc.c

@@ -161,9 +161,7 @@ static int libwebp_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
             ret = av_frame_get_buffer(alt_frame, 32);
             if (ret < 0)
                 goto end;
-            av_image_copy(alt_frame->data, alt_frame->linesize,
-                          frame->data, frame->linesize,
-                          avctx->pix_fmt, frame->width, frame->height);
+            av_frame_copy(alt_frame, frame);
             frame = alt_frame;
         }
         pic->use_argb  = 0;

libavfilter/vf_copy.c

@@ -37,9 +37,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
         return AVERROR(ENOMEM);
     }
     av_frame_copy_props(out, in);
-    av_image_copy(out->data, out->linesize, in->data, in->linesize,
-                  in->format, in->width, in->height);
-
+    av_frame_copy(out, in);
     av_frame_free(&in);
     return ff_filter_frame(outlink, out);
 }