TTML Live Extensions Module

W3C spec for live TTML/EBU-TT-Live subtitle streaming extensions, niche companion to IMSC.

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Related resources

• IMSC 1.2 — TTML Profiles for Internet Media Subtitles and CaptionsLatest stable W3C spec text for IMSC 1.2, the base standard behind most subtitle delivery in streaming.
• EBU Tech 3380: EBU-TT-D Subtitling Distribution FormatEBU's TTML-based subtitling distribution format spec designed for DASH/OTT delivery.
• W3C IMSC Test SuiteOfficial IMSC1 conformance test suite; several tests double as EBU-TT-D conformance tests.
• EBU-TT-D and IMSC1 Convergence (IBC2015)EBU/W3C technical paper documenting the convergence of EBU-TT-D and IMSC1 subtitle standards.
• EBU Tech 3380: EBU-TT-D SpecificationOfficial EBU technical specification document for EBU-TT-D subtitle/caption distribution format.
• Netflix Timed Text Style GuidesNetflix's official hub of subtitle/caption style guide requirements and per-language templates, an industry-standard captioning reference.
• Disney Dolby Vision Best Practices Guide v1.3.1Official Disney mastering spec detailing Dolby Vision L0/L1/L2/L5/L6/L8 metadata layers and trim requirements per content type.
• MPEG-5 Standards Overview (EVC & LCEVC)Overview of MPEG-5 Part 1 (EVC) and Part 2 (LCEVC) codec standards with links to specifications.
• MPEG Basics (Chiariglione)Explanation of MPEG standardization process and organizational structure by MPEG founder Leonardo Chiariglione.
• Video Coding Experts Group (VCEG)Overview of ITU-T's Video Coding Experts Group and its joint work with MPEG (JVET) developing codecs beyond VVC.
• HbbTV Reference ApplicationMIT-licensed reference DASH player with PlayReady/Marlin/ClearKey test material including cbcs streams, from the official HbbTV Association.
• Dolby.io Media APIs — Developer ToolsOfficial Dolby.io reference documentation for Media APIs developer tooling.
• Netflix Dolby Vision HDR Mastering GuidelinesOfficial Netflix delivery specification for Dolby Vision mastering, covering DV 4.0/2.9 profile requirements and IMF packaging.
• SMPTE ST 2110 — Professional Media over Managed IP NetworksOfficial SMPTE standard page for ST 2110, the professional media-over-IP suite (2025 Emmy-winning standard with EBU and VSF).
• AIMS Alliance (Alliance for IP Media Solutions)Industry alliance driving adoption of open IP standards (SMPTE ST 2110, NMOS) for professional media infrastructure interoperability.