libavcodec/proresenc.c:421: error: Uninitialized Value
  The value read from sign was never initialized.

libavcodec/proresenc.c:421:9: 
419.         delta    = dc - prev_dc;
420.         new_sign = GET_SIGN(delta);
421.         delta    = (delta ^ sign) - sign;
             ^
422.         code     = MAKE_CODE(delta);
423.         bits    += estimate_vlc(ff_prores_dc_codebook[codebook], code);
