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Re: Fonts WG Charter feedback

From: Jonathan Kew <jonathan@jfkew.plus.com>
Date: Wed, 1 Jul 2009 23:44:35 +0100
Cc: www-font@w3.org
Message-Id: <9BD4FE4B-57C3-450A-9DE2-53356F949620@jfkew.plus.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
On 1 Jul 2009, at 21:56, Tab Atkins Jr. wrote:

> I'm also fine with this sort of proposal (in addition to raw TTF/OTF
> support), though I'd prefer compression be mixed into the proposal as
> well.  The proposal already includes subsetting support for
> bandwidth-conservation reasons, and good compression has been shown to
> have a significant effect on several fonts.  We've already gotten some
> interesting looks at the efficacy of different compression techniques,
> and it shouldn't be difficult to assemble a representative sample of
> fonts and do some direct testing among the different proposals (which
> Vladimir listed).

Testing isn't difficult, although deciding what constitutes a  
"representative sample of fonts" might be trickier. Using gzip to  
compress various fonts, I've seen size reductions varying from around  
36% up to 64%, with most fonts somewhere close to the 50% mark. We  
also know that LZMA and MTX both tend to do better.

> I don't see any good reason to make compression optional in a new
> webfont format.  Using existing uncompressed TTF/OTF has benefits (no
> effort at all, and already works in most major UAs), but if we're
> going to the effort of defining a new standard webfont format as well,
> we might as well make it truly worth it.

Yes, this is my view as well. I believe useful compression can be  
included without significantly greater effort for implementers  
(slightly greater, yes, but not enough to present a hindrance to  
adoption), and of course with no additional burden at all for users,  
and will provide long-term benefits in real-world usage.

And of course, if compression is a standard part of the format (rather  
than optional), there is no longer any need for table-name obfuscation.

> It's been shown that
> standard gzip is significantly less efficient than certain other
> methods,

Agreed. Personally, I think the stability and ease of implementation  
that gzip offers outweigh this; if vendors can support the format with  
a few dozen (ok, maybe a few hundred) lines of code wrapped around  
calls to zlib, this is a considerably lower barrier to adoption than  
adding a dependency on lzmalib (whose license would, I think, prevent  
some browsers using it) or the LZMA SDK (a lower-level and more  
complex interface, as I understand it), or including a considerable  
amount of new code to support MTX.

So my personal preference would be for gzip/zlib-based .zot, but I'd  
be happy to implement any of these that we can agree on.

> so it would be worthwhile in my opinion to standardize on one
> of these and make it part of the proposal.
>
> However, I just saw your most recent email, and agree that including
> compression would be more difficult than not doing so, but I still
> strongly feel that the benefits are worthwhile here.

Having just written up the draft ZOT format this morning, I went ahead  
and wrote a compression tool this evening (of course, virtually all  
the real work is done by freely-available libraries). As a Perl  
script, the .ttf/.otf-to-.zot compressor is less than 50 lines of  
code. A decompressor would be very similar. I don't think that's an  
excessive level of difficulty, for the benefits such a format would  
give us.

Anyone interested is welcome to a copy, of course.

JK
Received on Wednesday, 1 July 2009 22:45:21 GMT

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