> - better table analysis with ability to substract successive elements
I'd never seen a single case where a simple delta was the best solution,
actually. Sometimes just a proper 2D context is enough, sometimes its
good to subtract an extrapolation by some previous lines, but never
simple delta was the best.
Btw, I'm currently thinking about a design with dynamic symbol ranking
for unary coding. Well, typical solution is to sort symbols by context
order, then by MtF rank (aka number of different symbols since last
occurence). And it works much better than seemingly "more valid"
solutions like descending probability order. But anyway these are
empiric methods without any foundations.
Well, it might seem unrelated, but its actually the same thing as with
deltas in 2D table encoding. I think its obvious if you consider unary
encoding - delta gives rank0 to the same value as previous etc.
So, my current opinion is that rank0 should be assigned to the symbol
with max codelength in some context (descending codelength order).
Higher (=lesser) rank usually means more complex model and more precise
estimation in unary schemes, so that's why.
> - segmentation (it seriously improves compression for durilca - look at MFC
> results with and without -t1 switch). http://www.compression.ru/ds/seg_file.rar
> is publicshed by DS, durilca's author - i don't know whether it is technique
> actually used there
-t1 - segmentation of file (default: (5,(0-3)));
k - precision of segmentation;
(b1-t1) - apply trick number t1 to block number b1;
(0-t1) - apply trick number t1 to all blocks;
Actually, in first durilca releases was even a hidden "-l" switch
for dumping these segments into separate files... With it I made
a bruteforce optimizer of durilca parameters for Werner