Methods and apparatus for reducing storage size
First Claim
1. A mechanism for reducing storage size needed for information represented by input data present in a randomly accessible memory window, the mechanism comprising:
- (a) a prediction-based entropy encoder operatively coupled to receive an input data stream sourced from the memory window;
(b) a walk generator operatively coupled to the memory window for defining a sequence of address signals supplied to the memory window;
(c) a compression efficiency evaluator operatively coupled to measure a length of encoded output produced by the entropy encoder in response to an input data stream received from the memory window for a given sequence of address signals defined by said walk generator and operatively coupled to measure a length of input data stream supplied to the entropy encoder in response to the given sequence of address signals;
the compression efficiency evaluator calculating a corresponding compression efficiency value as a function of said measured lengths of encoded output and length of input data stream; and
(d) a walk modifier operatively coupled to the compression efficiency evaluator and to the walk generator and structured to supply two or more different walk definitions to the walk generator and structured to determine, by trial and error operation of the walk generator and of the encoder, which of the two or more walk definitions causes the compression efficiency evaluator to calculate a superior compression efficiency value.
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Abstract
Prediction-based compression engines are spoon-fed with sequentially efficiently compressible (SEC) streams of input data that make it possible for the compression engines to more efficiently compress or otherwise compact the incoming data than would be possible with streams of input data accepted on a TV-raster scan basis. Various techniques are disclosed for intentionally forming SEC input data streams. Among these are the tight packing of alike files or fragments into concatenation suitcases and the decomposition of files into substantially predictably consistent (SPC) fragments or segments that are routed to different suitcases according to their type. In a graphics-directed embodiment, image frames are partitioned into segment areas that are internally SPC and multidirectional walks (i.e., U-turning walks) are defined in the segment areas where these defined walks are traced during compression and also during decompression. A variety of pre-compression data transformation methods are disclosed for causing apparently random data sequences to appear more compressibly alike to each other. The methods are usable in systems that permit substantially longer times for data compaction operations than for data decompaction operations.
19 Citations
33 Claims
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1. A mechanism for reducing storage size needed for information represented by input data present in a randomly accessible memory window, the mechanism comprising:
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(a) a prediction-based entropy encoder operatively coupled to receive an input data stream sourced from the memory window; (b) a walk generator operatively coupled to the memory window for defining a sequence of address signals supplied to the memory window; (c) a compression efficiency evaluator operatively coupled to measure a length of encoded output produced by the entropy encoder in response to an input data stream received from the memory window for a given sequence of address signals defined by said walk generator and operatively coupled to measure a length of input data stream supplied to the entropy encoder in response to the given sequence of address signals;
the compression efficiency evaluator calculating a corresponding compression efficiency value as a function of said measured lengths of encoded output and length of input data stream; and(d) a walk modifier operatively coupled to the compression efficiency evaluator and to the walk generator and structured to supply two or more different walk definitions to the walk generator and structured to determine, by trial and error operation of the walk generator and of the encoder, which of the two or more walk definitions causes the compression efficiency evaluator to calculate a superior compression efficiency value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification