7/2/2023 0 Comments Lzip compression![]() ![]() In practical terms, a trivial lossless compression algorithm eliminates those high bits that are so often zero, but even a very advanced lossless algorithm will have trouble getting further compression benefit vs. ![]() In contrast to the high-SNR image and text data used by most of the populace, scientists, and geoscientists in particular have instruments that use a very large dynamic range with high sensitivity.įor the radio science and scientific camera domains (two areas of my expertise), this typically means 16-bit high speed ADCs where most of the time, several bits are uniformly zero, and the rest of the bits are highly random, with a slowly changing bias value. Nature is an incredibly powerful random number generator–the opposite of what compression algorithms need. ![]() Self-similarities, autocorrelation, and the like. Lzip -Ĭompression of very noisy datasets: why is there often little advantage in noisy geoscience datasets for high compression settings?Īt the most basic level, lossless compression is about finding redundancies in the files. It may be possible to tweak further improvements by using dictionary size and match length options, if someone has an extremely large noisy dataset compression problem (e.g. Similar results for LZMA compression options for large datasets of geoscience auroral video. It’s immediately evident that for large, high-entropy (noisy natural geoscience data) that very low compression settings are appropriate. LZIP benchmarks: for a 106.9 MByte 16-bit software defined radio dataset (a short test file) I found the table below. Tar -I didn’t work for lzip: for some reason, on my PC, the -I 'lzip -0' option of tar doesn’t have any effect–it uses the -9 option of lzip regardless. See the benchmark observations for that greatly increased CPU time doesn’t help compress much more. This compresses the files down to 30-50 % of their original size while being as fast as possible. LZIP options: plzip is the multithreaded version of lzip that uses all the virtual cores of your CPU, to go at least N times faster when N is the number of physical CPU cores you have in your PC. Plzip -k -0 my.big -k do NOT have lzip delete the original file ![]()
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