//! average deltas
        for(int i=0;i<2;i++) {
            if(dif[i].size()) {
                u32 step = (dif[i].size()<<8) / 8;
                u32 pos  = 0;

                for(int j=0;j<8;j++) {
                    s64 total = 1;
                    s64 val   = (s64)(dif[i][(j*step)>>8]);

                    pos += step;
                    for(int k=1;(pos>>8);k++) {
                        val += (s64)(dif[i][j+k]); total++;
                        pos -= 1<<8;
                    }

                    val <<= 16;
                    val  /= total;
                    //if(val < -0x80000000) val = -0x80000000;
                    //if(val >  0x7FFFFFFF) val =  0x7FFFFFFF;

                    ad_Step[i*8 + j] = (s32)val;
                }
            }
        }