let pair_chmap = self.pairs[i].read_hdr_v2(&mut br)?;
self.pairs[i].start_ch = start_ch;
validate!((chmap & pair_chmap) == 0);
let pair_chmap = self.pairs[i].read_hdr_v2(&mut br)?;
self.pairs[i].start_ch = start_ch;
validate!((chmap & pair_chmap) == 0);