libswscale/swscale.c:1022: error: Uninitialized Value
  The value read from A was never initialized.

libswscale/swscale.c:1022:29: 
1020.             int needAlpha = CONFIG_SWSCALE_ALPHA && c->alpPixBuf;
1021.             YSCALE_YUV_2_RGBX_FULL_C(1<<21, needAlpha)
1022.                 dest[aidx]= needAlpha ? A : 255;
                                  ^
1023.                 dest[0]= R>>22;
1024.                 dest[1]= G>>22;
