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RE: Compression was: What is wrong with SVG?

From: Leonard Rosenthol <leonardr@lazerware.com>
Date: Mon, 12 Jun 2000 12:15:55 -0400
Message-Id: <a04310106b56abb283283@[207.29.200.50]>
To: Jon Ferraiolo <jferraio@Adobe.COM>, Dave J Woolley <DJW@bts.co.uk>
Cc: www-svg@w3.org
At 7:35 AM -0700 6/12/00, Jon Ferraiolo wrote:
>2) Custom gzip compression dictionaries (e.g., an SVG-specific dictionary)
>doesn't provide any compression benefit in most cases because of how good
>of a job gzip does in creating dictionaries automatically

	Interesting, since my experience in using a "starting table" 
with text data (any type, not specifically SVG or XML) yields a good 
couple of percentage points on compression.  Now, I've done with this 
different algorithms (for example, the one used by StuffIt) than 
gzip, which would also make a difference.


>4) A newer compression scheme, bzip (I think that is its name), looks
>promising as a way to compress XML data even more than gzip. (Howver, bzip
>isn't part of HTTP 1.1)

	bzip has some nice advantages over gzip, but it's still in its infancy.


>Overall, I doubt if an SVG-specific compression scheme would be worth the
>effort.
>
	Especially if you are going to then send it over a compressed 
line (like a full HTTP 1.1 implementation), since compression over 
compression doesn't work well - unless you do something smart like 
the old modem protocols (V.42, etc.) used to in detecting already 
compressed data.


Leonard
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Received on Monday, 12 June 2000 12:51:57 GMT

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