libavcodec/fmvc.c:150: error: Uninitialized Value
  The value read from opcode was never initialized.

libavcodec/fmvc.c:150:17: 
148.             }
149. 
150.             if (opcode >= 0x40) {
                     ^
151.                 bytestream2_skip(gb, 1);
152.                 pos = - ((opcode >> 2) & 7) - 1 - 8 * bytestream2_get_byte(gb);
