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Re: Binary Efficiency

From: Daniel Berlin <dberlin_at_dberlin.org>
Date: 2003-06-27 19:40:00 CEST

> The algorithm we use to create binary deltas is called vdelta. It's a
> block-copy delta algorithm (i.e., the output does not contain context
> information) and it's also a complression algorithm, although the
> compression is not as good as the one used by zip or bzip2 (there's a
> speed vs. compression quality tradeoff here).

It's better than zip, actually.
Not quite as good as *gzip*, however (the range coding + etc changes i
submitted as svndiff1 make it as good as gzip).
The main feature of bzip2 is the burrows-wheeler-transform, which we
could easily apply pre-vdelta, or pre-range coding, if we wanted to, in
order to increase the compression.
It would just be slower to *compress* (unbwt is much faster).

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Received on Fri Jun 27 19:40:55 2003

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