libavcodec/fmvc.c:153: error: Uninitialized Value
  The value read from opcode was never initialized.

libavcodec/fmvc.c:153:17: 
151.                 bytestream2_skip(gb, 1);
152.                 pos = - ((opcode >> 2) & 7) - 1 - 8 * bytestream2_get_byte(gb);
153.                 len =    (opcode >> 5)      - 1;
                     ^
154. 
155.                 bytestream2_init(&gbc, pb->buffer_start, pb->buffer_end - pb->buffer_start);
