ISO/IEC 14496-22:2019

Overview

ISO/IEC 14496-22:2019 - "Information technology - Coding of audio‑visual objects - Part 22: Open Font Format" specifies the Open Font Format (OFF). The standard defines the file organization, data structures and table formats used by Open Font Format fonts, covering both TrueType and Compact Font Format (CFF) outlines. It provides the normative details developers need to implement compliant font rendering, text layout/shaping, and font variation support in operating systems, browsers, typesetting engines and authoring tools.

Key topics and technical requirements

The standard is comprehensive and structured around the OFF file model and individual font tables. Key technical topics include:

• Top-level OFF organization: offset table, table directory, checksums and font collection (TTC) structures.
• Required common tables: character-to-glyph mapping (cmap), font header (head), horizontal metrics (hhea, hmtx), maximum profile (maxp), naming (name), OS/2 global font information, and post.
• TrueType outline support: tables such as glyf, loca, cvt, and bytecode program tables (fpgm, prep).
• CFF/CFF2 outline support: Compact Font Format tables for PostScript-style outlines.
• Glyph formats beyond outlines: SVG table for vector SVG glyphs, color bitmap tables (CBDT/CBLC, sbix), and legacy bitmap tables (EBDT/EBLC).
• Color and palette support: COLR and CPAL for layered color glyphs and palette management.
• Advanced typographic layout: layout tables and engines-GDEF, GSUB (glyph substitution), GPOS (glyph positioning), BASE, JSTF, MATH-including scripts, feature lookups and coverage formats.
• Font variations (variable fonts): variation axes, tuple and item variation stores, interpolation mechanisms and related tables (avar, cvar etc.).
• Optional and auxiliary tables: digital signatures (DSIG), device metrics (hdmx, VDMX), kerning, metadata (meta), and more.

Practical applications and target users

This standard is essential for:

• Font developers and foundries producing OFF/OTF/TTF fonts and variable fonts.
• Browser and OS developers implementing font rendering engines, shaping and layout (harfbuzz, DirectWrite, Core Text).
• Typesetting and desktop publishing software vendors ensuring accurate glyph substitution, positioning and complex script support.
• Digital content creators who rely on consistent text rendering across platforms, including color and SVG glyph support for emojis and icons.
• Tooling authors building font validators, converters, editors and font viewers.

By following ISO/IEC 14496-22:2019 implementers ensure interoperability, predictable shaping/layout behavior, and support for modern features like variable fonts, color glyphs and advanced typographic controls.

Related standards

The OFF standard combines and references TrueType and PostScript/CFF technologies. It is published as Part 22 of the ISO/IEC 14496 series (MPEG‑4 family) and complements platform-specific font APIs and rendering specifications used by operating systems and web engines.