Data compression system for successively applying at least two data compression methods to an input data stream
US4988998A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 5, 1989 |
| Grant date | Jan 29, 1991 |
| Priority date | — |
| Expiry date | Sep 5, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M7/3088
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
The improved data compression system concurrently processes both strings of repeated characters and textual substitution of input character strings. In this system, the performance of data compression techniques based on textual substitution are improved by the use of a compact representation for identifying instances in which a character in the input data stream is repeated. This is accomplished by nesting a run length encoding system in the textual substitution system. This structure adds the recognition of runs of a repeated character before the processor performs the textual substituted data compression operation. A further performance improvement is obtained by expanding the alphabet of symbols stored in the compressor's dictionary to include both the characters of the input data stream and repeat counts which indicate the repetition of a character. The handling of these repeat counts by the textual substitution based compression technique is no different than the handling of characters, or certain modifications are made in the handling of repeat counts.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.