[MPEG-OTSPEC] AHG Zoom Meeting announcement and agenda

Thu Dec 14 20:39:21 CET 2023

Thank you Vlad.

For my own action-items, I filed seven issues for Liam to act on:

https://github.com/harfbuzz/boring-expansion-spec/issues?q=is%3Aissue+in%3Atitle+%22%5BISO%5D%22+

Feedback from others is welcome.

The two other action-items I have are:

  - Change some Coverage/ClassDef offsets to 32bit. I'll do that on a
Google Docs that Liam will then take from.

  - Separate `VARC` table. I hope to have a draft soon. It's currently
being designed in:

    https://github.com/harfbuzz/boring-expansion-spec/issues/103

behdad
http://behdad.org/

On Tue, Dec 12, 2023 at 11:18 AM Vladimir Levantovsky <
vladimir.levantovsky at gmail.com> wrote:

> Dear all,
>
> Thank you for your active participation in the AHG Zoom meeting today.
> Like we discussed during the call, we will continue the discussion of
> remaining issues offline on this email list and on GitHub (see summary
> below) and will reconvene again for another AHG Zoom meeting on January 9,
> 2024 at 15:00 UTC. This will allow us additional time for final corrections
> and clarifications (if needed) to be completed prior to the input
> contribution deadline of Jan. 15 [for the next WG meeting taking place on
> Jan. 22-26, 2024).
>
> Here is a brief summary of the discussion and the resolutions / action
> items (my apologies if I missed anything - please feel free to comment on
> it):
> 1. On "Beyond 64K glyph limit" proposed changes
> - Introduce new 'MAXP' table tag duplicating both table versions (0.5 and
> 1.0) and updating data fields as necessary (considering the outcome of any
> additional discussions we may have);
> - We will not deprecate GSUB contextual substitutions (type 5 and type 7).
> - On glyph substitutions: while the number of glyphs in a ligature won't
> be affected by increased number of glyphs within a font, the number of
> possible ligatures and glyph substitutions may increase as a result of
> glyph limit increase. Coverage tables can become quite large - we discussed
> and agreed that certain counts and offsets need to be revisited
> (potentially changing coverage / classdef offsets from Offset24 to Offset32
> data type.
> - Font collections: in order to enable the use of new / hybrid fonts as
> part of a collection, we agreed to introduce two new TTC header formats
> bumping their minor versions to .1 and adding two new fields "numFonts" and
> "tableDirectoryOffsets" in each header format.
> - COLR table: future changes to accommodate a larger number of base glyphs
> would be needed. As an interim solution, in order to enable the use of a
> larger number of components we agreed to introduce a new PaintFormat.
> - Cubic outlines / control points: while discussing flags (bit 7) we
> agreed that unnecessary constraints can be removed allowing the bit7 flag
> to be set on both off- and on-curve points. In addition, the current
> specification is too concise and may need to clarify runtime behaviour.
> - Variable composites: this section will be moved out of the GLYF table
> into a separate VARC table. to be drafted and presented for review and
> offline discussion by the end of this week (before or on Dec. 15).
> 2. Working Draft updates:
> - Previously discussed and agreed changes for representative instance and
> condition value proposals have been introduced in the last revision; there
> are additional changes needed to address technical issues in the Condition
> Table specification (2nd paragraph, see comment in the WD text). Peter C.
> will review the spec changes that were introduced as part of OT 1.8.4 / 1.9
> updates and prepare an input contribution to address this and other
> portions of the OFF.
> 3. Extra topics:
> - We discussed the possibility of making CPAL optional to allow having
> COLR table without CPAL;
> - There was a brief discussion of a prior attempt to introduce 'dmap' (as
> in delta 'cmap') table for use in TTCs.
> - Previously, we started the discussion of the "Feature variations: New
> substitution mechanism" document as part of the Portland AHG meeting in
> August; we ran out of time and failed to discuss it during the AHG meeting
> in September and postponed it until after the October WG meeting. Skeff
> will prepare a draft proposal outlining the spec changes, and we will
> review and discuss it both offline and at the upcoming Jan. 9 AHG Zoom call.
>
> I will send a new meeting invite with the updated agenda for Jan. 9 Zoom
> call no later than Dec. 22nd.
>
> Thank you,
> Vladimir
>
>
> On Fri, Dec 1, 2023 at 2:43 PM Vladimir Levantovsky <
> vladimir.levantovsky at gmail.com> wrote:
>
>> Dear all,
>>
>> This is just a friendly reminder that we will have the AHG Zoom meeting
>> in just over a week from now, on Dec. 12.
>> Please review the agenda and the documents linked to each agenda item,
>> and prepare your comments ahead of time - this will help us make our
>> meeting time more productive [and, hopefully, shorten the meeting time to
>> better accommodate our Japanese participants who will be joining late at
>> night].
>>
>> Thank you,
>> Vladimir
>>
>>
>> On Wed, Nov 22, 2023 at 1:48 PM Vladimir Levantovsky <
>> vladimir.levantovsky at gmail.com> wrote:
>>
>>> Dear all,
>>>
>>> According to the AHG mandates I shared earlier, we will hold the AHG
>>> Zoom meeting on Dec. 12, 2024 at 15:00 UTC to review the proposed changes
>>> outlined in the "Technologies under consideration for ISO/IEC 14496-22
>>> 5th edition Open Font Format
>>> <https://www.google.com/url?q=https://www.mpeg.org/wp-content/uploads/mpeg_meetings/144_Hannover/w23265.zip&sa=D&source=calendar&usd=2&usg=AOvVaw25m9Ay4YP6_EiDUnFEMAwA>"
>>> document, and review the current version of the Working Draft of the 5th
>>> edition ISO/IEC 14496-22. Please see below the new Zoom meeting info and
>>> agenda, and please review the documents ahead of time to make the use of
>>> AHG meeting time most efficient and productive. (The meeting is scheduled
>>> for two hours but I hope that we will be able to accomplish our goals ahead
>>> of time.)
>>>
>>> The AHG meeting will be held under the following ISO rules and policies:
>>> - Declaration for participants in ISO activities
>>> <https://www.google.com/url?q=https://www.iso.org/declaration-for-participants-in-iso-activities.html&sa=D&source=calendar&usd=2&usg=AOvVaw2n2ZhkFMkQBjPrst6wyAbi>
>>> - ISO Code of Ethics and Conduct
>>> <https://www.google.com/url?q=https://www.iso.org/files/live/sites/isoorg/files/store/en/PUB100011.pdf&sa=D&source=calendar&usd=2&usg=AOvVaw3R7JNkexzilX-qCtg_vrzR>
>>> - Guideline for Implementation of the Common Patent Policy for
>>> ITU‑T/ITU‑R/ISO/IEC
>>> <https://www.google.com/url?q=https://www.iso.org/files/live/sites/isoorg/files/developing_standards/resources/docs/20221216_Guidelines_for_Implementation_of_the_Common_Patent_Policy.pdf&sa=D&source=calendar&usd=2&usg=AOvVaw3236BoeE5tQKR46VIx_R2a>
>>>
>>> Agenda
>>> 1. Overcoming 64K glyph limit and other updates.
>>> The content of the proposal summarized by the "Technologies under
>>> consideration for ISO/IEC 14496-22 5th edition Open Font Format
>>> <https://www.google.com/url?q=https://www.mpeg.org/wp-content/uploads/mpeg_meetings/144_Hannover/w23265.zip&sa=D&source=calendar&usd=2&usg=AOvVaw25m9Ay4YP6_EiDUnFEMAwA>"
>>> document has been updated by authors to accommodate comments and
>>> corrections discussed during the WG Font break-out group session - please
>>> review the changes:
>>> https://github.com/harfbuzz/boring-expansion-spec/blob/main/iso_docs/WG03-beyond-64k-glyphs-2023-11-20.pdf
>>> <https://www.google.com/url?q=https://github.com/harfbuzz/boring-expansion-spec/blob/main/iso_docs/WG03-beyond-64k-glyphs-2023-11-20.pdf&sa=D&source=calendar&usd=2&usg=AOvVaw06F5OqaCXHnNNtH0YMmg7N>
>>>
>>> Goal - review and discuss proposed table changes, and provide AHG
>>> recommendations;
>>>
>>> 2. Review the text of the updated WD of ISO/IEC 14496-22 5th edition
>>> Open font format
>>> <https://www.google.com/url?q=https://www.mpeg.org/wp-content/uploads/mpeg_meetings/144_Hannover/w23170.zip&sa=D&source=calendar&usd=2&usg=AOvVaw20amv1y6ikAAZdkad37arZ> that
>>> incorporates previously adopted changes to Condition Value and
>>> Representative Instance proposals.
>>> - Review tracked changes;
>>> - Review and discuss the current description of the Condition Table
>>> (2nd paragraph in particular, see comment in the WD text in subclause 6.2.9)
>>> that is technically incorrect since it is referring to non-existent
>>> version number of the ConditionSet table.
>>> Goal - provide AHG recommendation / future updates.
>>>
>>>
>>> Zoom meeting info: REDACTED
>>>
>>> Due to public availability of the email list archive, the meeting info
>>> cannot be shared on the list. All AHG members who previously joined AHG
>>> meetings in the past were already invited to attend.
>>> If you did not receive the invitation and would like to attend, please
>>> contact me directly.
>>>
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