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Re^2: Specialized data compression

by wanna_code_perl (Pilgrim)
on Sep 16, 2012 at 16:37 UTC ( #993930=note: print w/ replies, xml ) Need Help??


in reply to Re: Specialized data compression
in thread Specialized data compression

These suggestions were helpful. Thank you! Using deltas for x,y,z did help quite a bit.

The time delta derivative approach was interesting to think about, but would basically break the lossless compression I have going. At the moment, at least, I need to be able to reconstruct the original input verbatim, and the only way to do that is with fixed point arithmetic.

The one concession I was able to safely (verifiably) make is quantizing the time deltas that are close to the sensor frequency. The clock has a large (+/- 15%!) but predictable jitter pattern I was able to isolate and then basically RLE the result.

With the latest optimizations, I'm sitting at about 9:1 compression, which is acceptable. I was shooting for 10:1, but that last 33 KiB won't come easy.


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