ISO/IEC 14496-22:2009
(Main)Information technology — Coding of audio-visual objects — Part 22: Open Font Format
Information technology — Coding of audio-visual objects — Part 22: Open Font Format
ISO/IEC 14496-22:2009 specifies the Open Font Format (OFF) specification, the TrueType™ and Compact Font Format (CFF) outline formats, and the TrueType hinting language. It makes references to both TrueType and PostScript, as Open Font Format fonts combine the two technologies. Multimedia applications require a broad range of media-related standards. In addition to the typical audio and video applications, multimedia presentations include scalable 2D graphics and text supporting all languages of the world. Faithful reproduction of scalable multimedia content requires additional components including scalable font technology. The Open Font Format is an extension of the TrueType font format, adding support for PostScript font data. OFF fonts and the operating system services which support OFF fonts provide users with a simple way to install and use fonts, whether the fonts contain TrueType outlines or CFF (PostScript) outlines. The Open Font Format addresses the following goals: broader multi-platform support; excellent support for international character sets; excellent protection for font data; smaller file sizes to make font distribution more efficient; excellent support for advanced typographic control. PostScript® data included in OFF fonts may be directly rasterized or converted to the TrueType outline format for rendering, depending on which rasterizers have been installed in the host operating system. But the user model is the same: OFF fonts just work. Users will not need to be aware of the type of outline data in OFF fonts. And font creators can use whichever outline format they feel provides the best set of features for their work, without worrying about limiting a font's usability. OFF fonts can include the OFF Layout tables, which allow font creators to design broader international and high-end typographic fonts. The OFF Layout tables contain information on glyph substitution, glyph positioning, justification, and baseline positioning, enabling text-processing applications to improve text layout. As with TrueType fonts, OFF fonts allow the handling of large glyph sets using Unicode encoding. Such encoding allows broad international support, as well as support for typographic glyph variants. Additionally, OFF fonts may contain digital signatures, which enable operating systems and browsing applications to identify the source and integrity of font files, including embedded font files obtained in web documents, before using them. Also, font developers can encode embedding restrictions in OFF fonts which cannot be altered in a font signed by the developer.
Technologies de l'information — Codage des objets audiovisuels — Partie 22: Format de police de caractères ouvert
General Information
Relations
Buy Standard
Standards Content (Sample)
INTERNATIONAL ISO/IEC
STANDARD 14496-22
Second edition
2009-08-15
Information technology — Coding of
audio-visual objects —
Part 22:
Open Font Format
Technologies de l'information — Codage des objets audiovisuels —
Partie 22: Format de police de caractères ouvert
Reference number
ISO/IEC 14496-22:2009(E)
©
ISO/IEC 2009
---------------------- Page: 1 ----------------------
ISO/IEC 14496-22:2009(E)
PDF disclaimer
PDF files may contain embedded typefaces. In accordance with Adobe's licensing policy, such files may be printed or viewed but shall
not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading a PDF file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create the PDF file(s) constituting this document can be found in the General Info relative to
the file(s); the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the files are suitable for
use by ISO member bodies. In the unlikely event that a problem relating to them is found, please inform the Central Secretariat at the
address given below.
This CD-ROM contains the publication ISO/IEC 14496-22:2009 in portable document format (PDF), which
can be viewed using Adobe® Acrobat® Reader.
Adobe and Acrobat are trademarks of Adobe Systems Incorporated.
This second edition cancels and replaces the first edition (ISO/IEC 14496-22:2007), which has been
technically revised.
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2009
All rights reserved. Unless required for installation or otherwise specified, no part of this CD-ROM may be reproduced, stored in a retrieval
system or transmitted in any form or by any means without prior permission from ISO. Requests for permission to reproduce this product
should be addressed to
ISO copyright office • C
...
INTERNATIONAL ISO/IEC
STANDARD 14496-22
Second edition
2009-08-15
Information technology — Coding of
audio-visual objects —
Part 22:
Open Font Format
Technologies de l'information — Codage des objets audiovisuels —
Partie 22: Format de police de caractères ouvert
Reference number
ISO/IEC 14496-22:2009(E)
©
ISO/IEC 2009
---------------------- Page: 1 ----------------------
ISO/IEC 14496-22:2009(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
COPYRIGHT PROTECTED DOCUMENT
© ISO/IEC 2009
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO/IEC 2009 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/IEC 14496-22:2009(E)
Contents Page
Foreword .vi
Introduction.viii
1 Scope.1
2 Normative references.2
3 Abbreviated terms .2
4 The Open font file format.3
4.1 Description.3
4.2 Filenames .3
4.3 Data types.4
4.4 Table version numbers .5
4.5 Open font structure .5
4.5.1 Table directory.6
4.5.2 Calculating checksums.7
4.6 TrueType collections.7
4.6.1 The TTC file structure .7
4.6.2 TTC header.8
5 Open font tables .9
5.1 General .9
5.2 Required common tables.9
5.2.1 cmap – Character to glyph index mapping table .10
5.2.2 head – Font header.21
5.2.3 hhea – Horizontal header.23
5.2.4 hmtx – Horizontal metrics.24
5.2.5 maxp – Maximum profile.24
5.2.6 name – Naming table.25
5.2.7 OS/2 – Global font information table .45
5.2.8 Font class parameters - see informative Annex B for details.67
5.2.9 post – PostScript .67
5.3 TrueType outline tables .69
5.3.1 cvt – Control value table.69
5.3.2 fpgm – Font program .69
5.3.3 glyf – Glyf data.70
5.3.4 loca – Index to location.73
5.3.5 prep – Control value program .74
5.4 PostScript outline tables .74
5.4.1 CFF – PostScript font program (Compact Font Format) table.74
5.4.2 VORG – Vertical origin table.74
5.5 Bitmap glyph tables .76
5.5.1 EBDT – Embedded bitmap data table.76
5.5.2 EBLC – Embedded bitmap location table .80
5.6 Optional tables.88
5.6.1 DSIG – Digital signature table .88
5.6.2 gasp – Grid-fitting and scan conversion procedure.91
5.6.3 hdmx – Horizontal device metrics .92
5.6.4 kern – Kerning .93
5.6.5 LTSH – Linear threshold.96
5.6.6 PCLT – PCL 5 table.97
5.6.7 VDMX – Vertical device metrics .106
5.6.8 vhea – Vertical header table .108
© ISO/IEC 2009 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/IEC 14496-22:2009(E)
5.6.9 vmtx – Vertical metric table .112
6 Advanced Open Font layout tables.113
6.1 Advanced Open Font layout extensions .113
6.1.1 Overview of advanced typographic layout extensions.113
6.1.2 TrueType versus OFF layout .115
6.1.3 OFF layout terminology .115
6.1.4 Text processing with OFF layout .118
6.2 OFF layout common table formats .119
6.2.1 Overview.119
6.2.2 Table organization .120
6.2.3 Scripts and languages .122
6.2.4 Features and lookups.124
6.2.5 Common table examples .132
6.3 Advanced typographic tables.142
6.3.1 BASE Baseline table.142
6.3.2 GDEF – The glyph definition table .162
6.3.3 GPOS – The glyph positioning table.175
6.3.4 GSUB – The glyph substitution table .233
6.3.5 JSTF – The justification table .272
6.4 Layout tag registry.283
6.4.1 Scripts tags .283
6.4.2 Language tags.288
6.4.3 Feature tags.301
6.4.4 Baseline tags.360
7 Recommendations for OFF fonts.364
Byte ordering.364
'sfnt' version.364
Mixing outline formats.364
Filenames .364
Table alignment and length .365
First four glyphs in fonts .365
Shape of .notdef glyph .365
'BASE' table.366
'cmap' table.366
'cvt' table.366
'fpgm' table .366
'glyf' table.367
'hdmx' table .367
'head' table.367
'hhea' table.367
'hmtx' table .367
'kern' table .367
'loca' table.368
'LTSH' table.368
'maxp' table.368
'name' table.368
'OS/2' table.368
'post' table .369
'prep' table .369
'VDMX' table.369
8 General recommendations .369
8.1 Optimized table ordering .369
8.2 Non-standard (Symbol) fonts .370
8.3 Device resolutions.370
8.4 Baseline to baseline distances.370
8.5 Style bits .371
8.6 Drop-out control.372
8.7 Embedded bitmaps.372
iv © ISO/IEC 2009 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/IEC 14496-22:2009(E)
8.8 OFF CJK font guidelines.372
Annex A (informative) Patent Statements .373
Annex B (informative) Font Class and Font Subclass parameters.374
Annex C (informative) Earlier versions of OS/2 – OS/2 and Windows metrics.385
Annex D (informative) OFF Mirroring Pairs List.460
Bibliography.467
© ISO/IEC 2009 – All rights reserved v
---------------------- Page: 5 ----------------------
ISO/IEC 14496-22:2009(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as
an International Standard requires approval by at least 75 % of the national bodies casting a vote.
ISO/IEC 14496-22 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia Information.
This second edition cancels and replaces the first edition (ISO/IEC 14496-22:2007) which has been
technically revised.
ISO/IEC 14496 consists of the following parts, under the general title Information technology — Coding of
audio-visual objects:
⎯ Part 1: Systems
⎯ Part 2: Visual
⎯ Part 3: Audio
⎯ Part 4: Conformance testing
⎯ Part 5: Reference software
⎯ Part 6: Delivery Multimedia Integration Framework (DMIF)
⎯ Part 7: Optimized reference software for coding of audio-visual objects
⎯ Part 8: Carriage of ISO/IEC 14496 contents over IP networks
⎯ Part 9: Reference hardware description
⎯ Part 10: Advanced Video Coding
⎯ Part 11: Scene description and application engine
⎯ Part 12: ISO base media file format
⎯ Part 13: Intellectual Property Management and Protection (IPMP) extensions
⎯ Part 14: MP4 file format
vi © ISO/IEC 2009 – All rights reserved
---------------------- Page: 6 ----------------------
ISO/IEC 14496-22:2009(E)
⎯ Part 15: Advanced Video Coding (AVC) file format
⎯ Part 16: Animation Framework eXtension (AFX)
⎯ Part 17: Streaming text format
⎯ Part 18: Font compression and streaming
⎯ Part 19: Synthesized texture stream
⎯ Part 20: Lightweight Application Scene Representation (LASeR) and Simple Aggregation Format (SAF)
⎯ Part 21: MPEG-J Graphics Framework eXtensions (GFX)
⎯ Part 22: Open Font Format
⎯ Part 23: Symbolic Music Representation
⎯ Part 24: Audio and systems interaction
⎯ Part 25: 3D Graphics Compression Model
© ISO/IEC 2009 – All rights reserved vii
---------------------- Page: 7 ----------------------
ISO/IEC 14496-22:2009(E)
Introduction
The International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC)
draw attention to the fact that it is claimed that compliance with this document may involve the use of a patent.
The ISO and IEC take no position concerning the evidence, validity and scope of this patent right.
The holder of this patent right has assured ISO and IEC that he is willing to negotiate licences under
reasonable and non-discriminatory terms and conditions with applicants throughout the world. In this respect,
the statement of the holder of this patent right is registered with ISO and IEC. Information may be obtained
from the companies listed in Annex A.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights other than those identified in Annex A. ISO and IEC shall not be held responsible for identifying any or
all such patent rights.
viii © ISO/IEC 2009 – All rights reserved
---------------------- Page: 8 ----------------------
INTERNATIONAL STANDARD ISO/IEC 14496-22:2009(E)
Information technology — Coding of audio-visual objects —
Part 22:
Open Font Format
1 Scope
i
This part of ISO/IEC 14496 specifies the Open Font Format (OFF) specification, the TrueType™ and
Compact Font Format (CFF) outline formats, and the TrueType hinting language. Many references to both
TrueType and PostScript exist throughout this document, as Open Font Format fonts combine the two
technologies.
ii
NOTE This specification is based on the OpenType® font format specification, and is technically equivalent to that
specification.
Multimedia applications require a broad range of media-related standards. In addition to the typical audio and
video applications, multimedia presentations include scalable 2D graphics and text supporting all languages of
the world. Faithful reproduction of scalable multimedia content requires additional components including
scalable font technology. The Open Font Format is an extension of the TrueType font format, adding support
for PostScript font data. OFF fonts and the operating system services which support OFF fonts provide users
with a simple way to install and use fonts, whether the fonts contain TrueType outlines or CFF (PostScript)
outlines.
The Open Font Format addresses the following goals:
• broader multi-platform support;
• excellent support for international character sets;
• excellent protection for font data;
• smaller file sizes to make font distribution more efficient;
• excellent support for advanced typographic control.
iii
PostScript® data included in OFF fonts may be directly rasterized or converted to the TrueType outline
format for rendering, depending on which rasterizers have been installed in the host operating system. But the
user model is the same: OFF fonts just work. Users will not need to be aware of the type of outline data in
OFF fonts. And font creators can use whichever outline format they feel provides the best set of features for
their work, without worrying about limiting a font's usability.
OFF fonts can include the OFF Layout tables, which allow font creators to design broader international and
high-end typographic fonts. The OFF Layout tables contain information on glyph substitution, glyph positioning,
justification, and baseline positioning, enabling text-processing applications to improve text layout.
i
TrueType is a trademark of Apple Computer Incorporated.
ii
OPENTYPE is either a registered trademark or trademark of Microsoft Corporation in the United States and/or other
countries.
iii
PostScript is a registered trademark of Adobe Systems Incorporated.
© ISO/IEC 2009 – All rights reserved 1
---------------------- Page: 9 ----------------------
ISO/IEC 14496-22:2009(E)
As with TrueType fonts, OFF fonts allow the handling of large glyph sets using Unicode encoding. Such
encoding allows broad international support, as well as support for typographic glyph variants.
Additionally, OFF fonts may contain digital signatures, which enable operating systems and browsing
applications to identify the source and integrity of font files, including embedded font files obtained in web
documents, before using them. Also, font developers can encode embedding restrictions in OFF fonts which
cannot be altered in a font signed by the developer.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO/IEC 10646, Information technology — Universal Multiple-Octet Coded Character Set (UCS)
ISO/IEC 14496-18, Information technology — Coding of audio-visual objects — Part 18: Font compression
and streaming
TrueType Instruction Set,
Unicode 5.1,
3 Abbreviated terms
List of abbreviated terms.
ACF Average Character Face
ANSI American National Standards Institute
ASCII American Standard Code for Information Interchange
ATM Adobe Type Manager
BMP [Unicode] Basic Multilingual Plane (also known as UCS-2)
BTBD Baseline To Baseline Distance
CFF Compact Font Format
CID Character Identifier
CJK Chinese Japanese Korean [characters, ideographs, fonts, etc.]
CJKV Chinese Japanese Korean and Vietnamese
CV Control Value
CVT Control Value Table
DLL Dynamically Linked Library
FDEF Function Definition
GID Glyph ID
ICF Ideographic Character Face
IDEF Instruction Definition
IETF Internet Engineering Task Force
JIS Japanese Industrial Standard
LTR Left To Right
2 © ISO/IEC 2009 – All rights reserved
---------------------- Page: 10 ----------------------
ISO/IEC 14496-22:2009(E)
NLC National Language Council of Japan
OFF Open Font Format
OMPL OFF Mirroring Pairs List
OTF OpenType Font
PCL Printer Control Language
PPM, PPEM Pixels Per EM
PRC People's Republic of China
RTL Right To Left
TTC TrueType Collection
TTF TrueType Font
UCS Universal Character Set
UTF Unicode Transformation Format
UVS Unicode Variation Sequence
VM Virtual Memory
W3C World Wide Web Consortium
4 The Open font file format
4.1 Description
An Open font file contains data, in table format, that comprises either a TrueType or a PostScript outline font.
Rasterizers use combinations of data from the tables contained in the font to render the TrueType or
PostScript glyph outlines. Some of this supporting data is used no matter which outline format is used; some
of the supporting data is specific to either TrueType or PostScript.
4.2 Filenames
OFF fonts may have the extension .OTF or .TTF, depending on the kind of outlines in the font and the
creator's desire for compatibility on systems without native OFF support.
• In all cases, fonts with only CFF data (no TrueType outlines) always have an .OTF extension.
• Fonts containing TrueType outlines may have either .OTF or .TTF, depending on the desire for
backward compatibility on older systems or with previous versions of the font. TrueType Collection
fonts should have a .TTC extension
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.