SMPTE Timed Text in the
UltraViolet™ Common File
Format
Mike Dolan (TBT)
SMPTE Timed Text in the UltraViolet™
Common File Format
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Requirements & History
Relationship to SMPTE Timed Text
Extensions
Profiles & Constraints
Further Reading
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
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
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
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
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
Relationship to TTML & SMPTE-TT
SMPTE-TT
W3C TTML
CFF-TT
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
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
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
The Base “TT” Namespaces (2/3)
• 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
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
The Base “TT” Namespaces (3/3)
• 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 CEA608 data byte pairs)
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
CFF-TT Extension
• cff:forcedDisplayMode
– Support for “forced” subtitles
• Even when subtitle track is not enabled, some
special case text/images are displayed
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
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>
…
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
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
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
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
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
Constraints – Text Profile
• (all image-related attributes and
elements forbidden)
• Anamorphic text forbidden
• Blurred text forbidden
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
Constraints – Image Profile
• (all text-related attributes and elements
forbidden)
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
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/st2052-02010.pdf
• W3C TTML 1.0 2nd Edition (draft)
– http://dvcs.w3.org/hg/ttml/rawfile/tip/ttml10/spec/ttaf1-dfxp.html
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org
The End
• Author - Michael Dolan, TBT
– DECE Technical Working Group Co-Chair
– Member of SMPTE 24TB and W3C TTWG
– mailto:mdolan@newtbt.com
• Questions?
© 2012 SMPTE · The 2012 Annual Technical Conference & Exhibition · www.smpte2012.org