note wanna_code_perl <p>Thanks for the suggestions! It took me a few days to think this through and try some things.</p> <p>Indeed, per your suggestion I have tried deltas for x,y,z, although they don't all fit in 8 bits (some deltas will of course overflow 16-bit as well), so I use a variable width int (8, 16, or 32 bit), which was a pretty big win, even after compression.</p> <p>The bitwise transposition you refer to is interesting, but was complex and didn't change things much once xz got ahold of it.</p> 992886 992958