let mbs = self.mb_w * self.mb_h;
let mb_bits = if mbs < 64 { 6 } else { 32 - (mbs - 1).leading_zeros() } as u8;
let _offset = br.read(mb_bits)?;
let mbs = self.mb_w * self.mb_h;
let mb_bits = if mbs < 64 { 6 } else { 32 - (mbs - 1).leading_zeros() } as u8;
let _offset = br.read(mb_bits)?;