Merge commit 'd1b3fabe'

* commit 'd1b3fabe':
  h264: reset first_field if frame_start() fails for missing refs

See: d7599bd8Merged-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/h264.c

@@ -3751,8 +3751,11 @@ static int decode_slice_header(H264Context *h, H264Context *h0)
                 for(i=0; i<FF_ARRAY_ELEMS(h->last_pocs); i++)
                     h->last_pocs[i] = INT_MIN;
             ret = h264_frame_start(h);
-            if (ret < 0)
+            if (ret < 0) {
+                h0->first_field = 0;
                 return ret;
+            }
+
             h->prev_frame_num++;
             h->prev_frame_num        %= 1 << h->sps.log2_max_frame_num;
             h->cur_pic_ptr->frame_num = h->prev_frame_num;