ac_get(ac, gb, prob, &residual);
v = ((predict >> 15) ^ residual) & 1;
dsd[((i >> 3) * channels + ch) << 2] |= v << (7 - (i & 0x7 ));
ac_get(ac, gb, prob, &residual);
v = ((predict >> 15) ^ residual) & 1;
dsd[((i >> 3) * channels + ch) << 2] |= v << (7 - (i & 0x7 ));