libavcodec/vp8dsp.c:122: error: Uninitialized Value
  The value read from p0 was never initialized.

libavcodec/vp8dsp.c:122:5: 
120.     int a, f1, f2;
121. 
122.     a = 3*(q0 - p0);
         ^
123. 
124.     if (is4tap)
