libavcodec/h264_direct.c:392: error: Uninitialized Value
  The value read from mv[_] was never initialized.

libavcodec/h264_direct.c:392:13: 
390.                 b = mv[1];
391.         } else {
392.             a = mv[0];
                 ^
393.             b = mv[1];
394.         }
