rawenc: initialize coded_frame via avcodec_get_frame_defaults.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

libavcodec/rawenc.c

@@ -32,8 +32,8 @@
 static av_cold int raw_init_encoder(AVCodecContext *avctx)
 {
     avctx->coded_frame = (AVFrame *)avctx->priv_data;
+    avcodec_get_frame_defaults(avctx->coded_frame);
     avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
-    avctx->coded_frame->key_frame = 1;
     avctx->bits_per_coded_sample = av_get_bits_per_pixel(&av_pix_fmt_descriptors[avctx->pix_fmt]);
     if(!avctx->codec_tag)
         avctx->codec_tag = avcodec_pix_fmt_to_codec_tag(avctx->pix_fmt);