Method of producing a checkpoint which describes a box file and a method of generating a difference file defining differences between an updated file and a base file
First Claim
1. A method of producing a checkpoint which describes a base file, the method comprising:
- dividing the base file into a series of segments;
generating for each segment a segment description, wherein each segment description comprises a lossless signature and a plurality of lossey samples each describing the segment at a different level of resolution; and
creating from the generated segment descriptions a segments description structure as the checkpoint, wherein the segments description structure is created by selecting for each segment from among the plural lossey samples and lossless signature a description that adequately distinguishes the segment to the lowest level of resolution.
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Abstract
A checkpoint which describes a base file is produced by dividing the base file into a series of segments; generating for each segment a segment description; and creating from the generated segment descriptions a segment description structure as the checkpoint. The segment descriptions represent segments of the base file at a minimum level of resolution sufficient to represent distinctly the segment. A difference file which defines differences between an updated file and the base file is produced by generating at different levels of resolution segment descriptions for segments in the updated file and comparing the generated segment descriptions with segment descriptions in the checkpoint to identify matching and non-matching segments. Data identifying segments in the updated file that match segments in the base file and data representing portions of the updated file at a minimum level of resolution sufficient to represent distinctly the portion are stored as the difference file.
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Citations
17 Claims
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1. A method of producing a checkpoint which describes a base file, the method comprising:
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dividing the base file into a series of segments;
generating for each segment a segment description, wherein each segment description comprises a lossless signature and a plurality of lossey samples each describing the segment at a different level of resolution; and
creating from the generated segment descriptions a segments description structure as the checkpoint, wherein the segments description structure is created by selecting for each segment from among the plural lossey samples and lossless signature a description that adequately distinguishes the segment to the lowest level of resolution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of producing a morph list that defines an updated version of a base file with reference to the base file and a checkpoint for the base file, the method comprising:
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producing the checkpoint by dividing the base file into a series of segments, generating for each segment a segment description, wherein each segment description comprises a lossless signature and a plurality of lossey samples each describing the segment at a different level of resolution, and creating from the generated segment descriptions a segments description structure as the checkpoint, wherein the segments description structure is created by selecting for each segment from among the plural lossey samples and lossless signature a description that adequately distinguishes the segment to the lowest level of resolution;
defining a first segment at a start position in the updated file;
generating a segment description for the first segment;
comparing the segment description for the first segment with segment descriptions of the checkpoint; and
if a match is found, adding the matched segment description to the morph list and, if no match is found adding data in the first segment to the morph list. - View Dependent Claims (13, 14, 15, 16)
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17. A method of generating a difference file defining differences between an updated file and a base file, the method comprising:
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generating a checkpoint by dividing the base file into a series of segments, generating for each segment a segment description, wherein each segment description comprises a lossless signature and a plurality of lossey samples each describing the segment at a different level of resolution, and creating from the generated segment descriptions a segments description structure as the checkpoint, wherein the segments description structure is created by selecting for each segment from among the plural lossey samples and lossless signature a description that adequately distinguishes the segment to the lowest level of resolution;
generating at different levels of resolution segment descriptions for segments in the updated file and comparing the generated segment descriptions with segment descriptions in the checkpoint to identify matching and non-matching segments; and
storing as the difference file data identifying segments in the updated file that match segments in the base file and data representing portions of the updated file at a minimum level of resolution sufficient to represent distinctly the portion.
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Specification