Data Compression


Criteria

Survey Formats

Basics

Compression Methods

Data Formats


Applications and Projects

Freeware Applications

Freeware Libraries

Prof. Applications

Reference Data Sets

Calgary Corpus

Comparisons Calgary


Glossary

Index


Download


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Applications and Projects


Apart from the well-known market leaders there is a large number of suppliers offering their applications to the most different conditions. The following lists do not claim to be complete, but shall offer a rough survey.


A concrete comparison of the applications is difficult because the supported number of data formats strongly increases due to free libraries. Partially the applications support up to 20 or 30 formats and/or subformats.


Moreover some compression methods allow user defined settings for various attributes, e.g.:


dictionary sizes

memory requirements (encoder and/or decoder)

length of sequences to be analyzed

etc.


In addition, the performance varies strongly in dependence of the test environment (original data, hard and software platforms, etc.).


Prerequisite for an objective evaluation of the compression performance of a data format or application is a reference data set. This usually consists of a collection of original files and is arranged with regard to the different application profiles. The so-called "Calgary Text Compression Corpus" is the established quasi-standard.


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Data Compression Comparisons Calgary Corpus Open Source and Freeware Applications