let udelta = br.read_gammap_s()? * 2;
let vdelta = br.read_gammap_s()? * 2;
mc!(self.buf, src, dst, mx, my, xpos, ypos, w, h, ydelta, udelta, vdelta, self.width, self.height);
let udelta = br.read_gammap_s()? * 2;
let vdelta = br.read_gammap_s()? * 2;
mc!(self.buf, src, dst, mx, my, xpos, ypos, w, h, ydelta, udelta, vdelta, self.width, self.height);