Ulrik Mikaelsson authored Feb 02, 2020 and Erik de Castro Lopo committed May 03, 2020

> if the partition order is zero, n = frame's blocksize - predictor order
> else if this is not the first partition of the subframe,
>   n = (frame's blocksize / (2^partition order))
> else n = (frame's blocksize / (2^partition order)) - predictor order

if the partition order is zero, then partition_number can only be zero
if the partition order is zero, then
  (frame's blocksize / (2^partition order))
  is (frame's blocksize / 1) == frame's blocksize