qsv: Skip the packet if decoding failure

MediaSDK may fail to decode some frame, just skip it.
Otherwise, it will keep decoding the failure packet repeatedly
without processing any packet afterwards.
Signed-off-by: Ruiling Song <ruiling.song@intel.com>
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavcodec/qsvdec_h2645.c

@@ -153,8 +153,12 @@ static int qsv_decode_frame(AVCodecContext *avctx, void *data,
         }
 
         ret = ff_qsv_process_data(avctx, &s->qsv, frame, got_frame, &s->buffer_pkt);
-        if (ret < 0)
+        if (ret < 0){
+            /* Drop buffer_pkt when failed to decode the packet. Otherwise,
+               the decoder will keep decoding the failure packet. */
+            av_packet_unref(&s->buffer_pkt);
             return ret;
+        }
 
         s->buffer_pkt.size -= ret;
         s->buffer_pkt.data += ret;