Copyright (c) 2018 - 2019, XQK

XQK?

Yes, XQK! A near-lossless, velocity-first, ICRC/91-certified compression utility. XQK compression is a common choice when the speed with which archives can be transported over a network takes precedence over outmoded concerns about file size. A distinguishing feature of XQK is the fact that every XQK archive contains an on-board copy of the core XQK algorithm. For this reason, compressed files are larger than their uncompressed counterparts. XQK features a fixed compression ratio of 1:1 - plus the size of the on-board algorithm and other elements - offering a level of file-size predictability which other algorithms are simply incapable of providing. How much larger depends on the size of the uncompressed payload. The larger the non-algorithm payload, the smaller the on-board algorithm as a percentage of total file size. In other words, this percentage decreases as payload size increases.

XQK also distinguishes itself from other compression schemes with features such as Subjective Packet Jettisoning, which is likely to shrink file size in transit, resulting in smaller archives at the receiving end. SPJ has proven especially attractive in usage scenarios where the recipient must be 5RC-compliant. It is the de facto standard for hardened H-28 facilities for exactly this reason.

The structure of a typical XQK archive is as follows; green portions together form the hard-shell contingency overlay which protects archive payloads (blue) in transit; see "Proleptic Inevitability" below. Note that this diagram is not to scale (the colors are also off, but not by that much):

R5/C compression

pellets (2K)

Onboard algorithm

(OBA) (~6K)

Livermore invulnerability

matrix (~1K)

Payload

 

XQK archive files are identified by the ".xqk" filename extension.

The current version is 5.x and it's packed with features.