libavcodec/proresenc.c:275: error: Uninitialized Value
  The value read from sign was never initialized.

libavcodec/proresenc.c:275:9: 
273.         delta    = dc - prev_dc;
274.         new_sign = GET_SIGN(delta);
275.         delta    = (delta ^ sign) - sign;
             ^
276.         code     = MAKE_CODE(delta);
277.         encode_vlc_codeword(pb, ff_prores_dc_codebook[codebook], code);
