libavcodec/ffv1enc.c:321: error: Uninitialized Value
  The value read from a was never initialized.

libavcodec/ffv1enc.c:321:13: 
319. 
320.         for (x = 0; x < w; x++) {
321.             int b, g, r, av_uninit(a);
                 ^
322.             if (lbd) {
323.                 unsigned v = *((const uint32_t *)(src[0] + x * 4 + stride[0] * y));
