WebFonts Working Group Teleconference

05 Nov 2010

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<trackbot> Date: 05 November 2010

woff processing model

<jdaggett> discussion about chris l's email

<Vlad> If anyone wnats to join via Zakim bridge, please announce your intention to join in the WG email list

<jdaggett> http://lists.w3.org/Archives/Public/public-webfonts-wg/2010Nov/0010.html

<John> Suggestion to review uses of the term 'original font' and specify 'input font'.

<John> Proposal: change last sentence of first paragraph of introduction to read: 'User agents decode the WOFF file to restore the input font data such that it will display identically to that input font.'

<John> or: 'User agents decode the WOFF file to restore the font data such that it will display identically to the input font.'

<jdaggett> Vlad: based on defn of input file from chris

<jdaggett> Vlad: what if we add "no overlapping tables" to what chris has proposed

<Vlad> I suggest that the input should be defined as a "well-formed sfnt file" which conforms to the following requirements: no hidden data, non-overlapping tables, all tables padded to long boundaries and correct checksums

<jdaggett> John: get rid of "in general" in third para of introduction

<jdaggett> cslye: do we want to restrict woff to truetype, opentype etc.

<jdaggett> chris lilley arrives, bands play

<jdaggett> discussion of how far to push definition of "well-formed" opentype font

<jdaggett> attempting live editing of spec to define processing model

<jdaggett> discussion of whether diagrams are really necessary or not

<John> 'User agents decode the WOFF file to restore the font data such that it will display identically to the input font.'

<jdaggett> working on transforming "original" to "input"

<cslye> Let's define the term "input font" at the top (as any sfnt font, blah blah) and then use that term throughout the spec.

<John> The WOFF format is a container for the table-based sfnt structure used in e.g. TrueType [TrueType], OpenType [OpenType] and Open Font Format [OFF] fonts, hereafter referred to as sfnt fonts.

<John> The structure and contents of decoded font data exactly match those of a well-formed input font file.

<jdaggett> more discussion of round-tripping

<John> Suggested: 'The main body of the file consists of the same collection of font data tables as a well-formed input sfnt font, stored in the same order, except that each table MAY be compressed, and the sfnt table directory is replaced by the WOFF table directory.'

<Vlad> Doing spec edits to replace references to "original" font with input file.

This means that the overall font checksum of a

font decompressed from a conformant WOFF file will always match the checksum

in a well-formed input font

A well-formed input font does not have structural anomalies such as

incorrect padding, overlapping font tables, or

extraneous data between tables (which will be discarded by the WOFF


<jdaggett> break



Registration Template

action chris to write to iesg suggesting font/ top level type

<trackbot> Created ACTION-39 - Write to iesg suggesting font/ top level type [on Chris Lilley - due 2010-11-12].


action chris to add a media type registration remplate for woff, omitting the top level type

<trackbot> Created ACTION-40 - Add a media type registration remplate for woff, omitting the top level type [on Chris Lilley - due 2010-11-12].

<dsinger> have a look at the draft http://tools.ietf.org/html/draft-singer-font-mime-00

<dsinger> have a look at http://www.iana.org/assignments/media-types/index.html


<jfkthame_afk> for the Magic Number field:

<jfkthame_afk> The signature field in the WOFF header MUST contain the "magic number" 0x774F4646

<timeless> fwiw css => application/x-pointplus can be found in http://lists.w3.org/Archives/Public/www-style/1998Mar/0000.html

<Vlad> http://dev.w3.org/webfonts/WOFF/spec/

<dsinger> suggested text: Note that user agents need not necessarily reconstitute the original sfnt as a whole, and may reorder tables when decoding the WOFF file to sfnt form; they may access individual tables directly as needed. Under these circumstances the resulting sfnt will no longer be an exact copy of the original, and checksums or digital signature data may be invalidated as a result.

<jfkthame_afk> No overlapping tables: The offset and length values in the input sfnt table directory must not indicate overlapping byte ranges of the input font.

RESOLUTION: Proceed to Last Call on this document, final review of recent edits by Weds 10 Nov. publication aimed at 11 Nov.

Summary of Action Items

[End of minutes]

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