libavcodec/vp56.c:498: error: Uninitialized Value
  The value read from alpha_offset was never initialized.

libavcodec/vp56.c:498:5: 
496.     AVFrame *const p = s->frames[VP56_FRAME_CURRENT];
497.     int remaining_buf_size = avpkt->size;
498.     int is_alpha, av_uninit(alpha_offset);
         ^
499.     int res;
500. 
