SMPTE Timed Text in the UltraViolet™ Common File Format Mike Dolan (TBT)

SMPTE Timed Text in the UltraViolet™ Common File Format

Mike Dolan (TBT)

© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org

SMPTE Timed Text in the UltraViolet™ Common File Format• Requirements & History• Relationship to SMPTE Timed Text• Extensions• Profiles & Constraints• Further Reading


Requirements

• Subtitles– (language translation of dialog)– Comparable to DVD & Blu-ray functionality

• Closed Captions– (transcription of sound)– Comparable to CEA-708 as constrained by

FCC 47CFR79.102


Development History

• Subtitle design started in early 2009• DVB Subpictures first considered• W3C TTML (known as DFXP then) proposed in

late 2009• SMPTE-TT (with TTML) decided in early 2010• W3C TTML published in late 2010• SMPTE-TT published in late 2010• Refinements and constraints developed since


Relationship to TTML & SMPTE-TT

W3C TTML

SMPTE-TT

CFF-TT


The Base “TT” Namespaces (1/3)

• W3C TTML– Designed to be general purpose for many

use cases, not just subtitles and captions– A rich design destined to be subsetted for

applications• SMPTE-TT Extensions

– Images– Metadata



• SMPTE-TT Extensions – Images– Definition inline in the document or by

external URI– PNG format– Inline encoding via “Base64”– Attributes to insert in a region and define

justification



• SMPTE-TT Extensions – Metadata– General metadata defined for television

caption conversion:• Source format (e.g. “CEA-608”)• Conversion attributes

– General data carriage• Inline encoding via “Base64”• Used for “tunneling” data (e.g. exact original CEA-

608 data byte pairs)


CFF-TT Extension

• cff:forcedDisplayMode– Support for “forced” subtitles

• Even when subtitle track is not enabled, some special case text/images are displayed


Example XML

…<div>

<p region="subtitle1" begin="00:05:00" end="00:05:15“ cff:forcedDisplayMode=”true”>

This subtitle text is always displayed even when the subtitle track is not selected.

</p></div>…


Profiles

• Text– 708 FCC subset functionality– Well-defined Unicode for most Western languages– No image support

• Image– SMPTE-TT PNG file support

• Mainly intended for font glyphs

– No text support


Constraints - General

• Some TTML infrastructure complexity not needed to meet requirements

• Root container = video track width and height• Only 4 Active Regions maximum within root container• Simplified attribute syntax and semantics

– e.g. media timebase, text metrics• Detailed Rendering Model

– Maximum document size– Character and Image buffer model– Character and Image rendering throughput


Constraints – Text Profile

• (all image-related attributes and elements forbidden)

• Anamorphic text forbidden• Blurred text forbidden


Constraints – Image Profile

• (all text-related attributes and elements forbidden)


Further Reading

• DECE CFF Specification– http://www.uvvu.com/uv-for-business.php

• SMPTE-TT PDA– https://www.smpte.org/PDA_On-demand/SMPTE-TT

• SMPTE-TT Standards Overview– https://www.smpte.org/sites/default/files/st2052-0-

2010.pdf• W3C TTML 1.0 2nd Edition (draft)

– http://dvcs.w3.org/hg/ttml/raw-file/tip/ttml10/spec/ttaf1-dfxp.html


• Author - Michael Dolan, TBT– DECE Technical Working Group Co-Chair– Member of SMPTE 24TB and W3C TTWG– mailto:[email protected]

• Questions?

The End

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SMPTE Timed Text in the UltraViolet™ Common File Format Mike Dolan (TBT)