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Re: Announcing new font compression project

From: Chris Lilley <chris@w3.org>
Date: Mon, 2 Apr 2012 18:11:12 +0200
Message-ID: <1709775321.20120402181112@w3.org>
To: Thomas Phinney <tphinney@cal.berkeley.edu>
CC: www-font@w3.org
On Friday, March 30, 2012, 11:26:57 PM, Thomas wrote:

TP> It will be interesting to see the trade-off of compression gains
TP> versus performance analyzed in detail. Will the ideal tradeoff be
TP> different for mobile devices? They have both (often) lower bandwidth
TP> and usually less powerful CPUs, upping the stakes for finding the
TP> sweet spot in that tradeoff.

Good point.

Some compression schemes are asymmetric (take more effort to compress, but are easier to decompress) - zlib is one of those. This makes sense for content delivery because the compression happens once and the decompression happens multiple times. Where is LZMA on that?

Some compression schemes are CPU intensive while others work best with a large amount of memory. Some need a fixed minimum buffer size while others are adaptable (will work, but slower, with limited memory).

Another tradeoff that occurs to me is that with classic WOFF, tables that are not needed do not have to be decompressed (and in theory do not even have to be downloaded, if client and server support byte ranges, although I haven't seen that implemented for WOFF). With the new proposal, if the option is taken to use one compression stream for all tables, that advantage is lost. Perhaps there might be best practices on which sets of tables to compress together (which in turn requires info on which tables are used by various platforms).

-- 
 Chris Lilley   Technical Director, Interaction Domain                 
 W3C Graphics Activity Lead, Fonts Activity Lead
 Co-Chair, W3C Hypertext CG
 Member, CSS, WebFonts, SVG Working Groups
Received on Monday, 2 April 2012 16:11:43 UTC

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