Add support for EBU-TTML
The fifty-six (56) member nations of the European Broadcasting Union (http://en.wikipedia.org/wiki/European_Broadcasting_Union) produce and publish digital content enjoyed by users of the VLC Player. Some users of the VLC Player would like to concurrently read the EBU-compliant subtitles while viewing the content. These subtitle files can be characterized as "Timed-Text Markup Language" (TTML) files, and generally are published electronically with the TTML or XML file suffix/identifier.
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A description of such subtitles can be read here: https://tech.ebu.ch/files/live/sites/tech/files/shared/tech/tech3350.pdf.
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The XML schema for such subtitles is available here: https://tech.ebu.ch/files/live/sites/tech/files/shared/ebu-tt/ebu-tt-xml-schema-v.1.0.1.zip
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Sample files are available here: https://tech.ebu.ch/files/live/sites/tech/files/shared/ebu-tt/ebu-tt-samplesuite-for-Tech-3360-v_0_1_3.zip
Subtitles that comply with the EBU TTML family of specifications conform with the corresponding W3C standard: http://www.w3.org/TR/ttaf1-dfxp/.
Information
The following VLC Player general use-cases apply:
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The user is deaf or hearing-impaired.
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The user is not fluent in the original broadcast language, and the content provider enables the display of alternate-language subtitles. (Such usage could be part of a formal academic program, or informal.)
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The playback occurs in an environment in which the volume must be limited, or ambient noise is such that comprehension is difficult.
Currently the VLC Player supports the use-cases principally in its ability to display subtitles in the Subfile-Rip Text (SRT) file-format. An elementary subtitle file-format that was created to extract (rip) textual subtitles from physical media, SRT is less than ideal for the hearing-impaired. For example, differently colored text can not be displayed, with which the dialogue in conversations can be visually bound to the speaking actor.
EBU-Nations have been publishing media via the web that includes EBU-compliant subtitles; this is an outgrowth of the closed-captioning provided by Teletext. These TTML-format files have rich formatting features, as determined by the authoring entity. While the subtitling often results from laws mandating equality in accessibility to electronic media, the richness of formatting is a matter under the broadcasters' determination. When converted to SRT-format -- to enable the viewing of the subtitles within the VLC Player -- all rich text formatting is lost. Comprehension correspondingly suffers.
The need for VLC Player to support the display of TTML-format subtitles has been recognized for some time (for example, https://wiki.videolan.org/OPW_Summer_2014/#Timed_Text_TTML_support). The concept of ripping subtitles from DVD media has become an anachronism with the advent of electronic media delivery. In the same way that MPEG-2 support did not obviate a need for the VLC Player to support MP4-formatted files, VLC's current SRT support should not impede the implementation of functionality to display native TTML-formatted subtitles.
EBU efforts are progressing much more rapidly than the W3 standards, which are largely based on the input of SMEs from EBU-Nations. VLC Player support of EBU-compliant electronic subtitles are at no risk of falling outside of some future W3C standards track.
This page provides a convenient portal for EBU TTML information: https://tech.ebu.ch/ebu-tt
The public television broadcasters in German-speaking countries (like Switzerland's SRF, or Germany's ZDF) are making impressive strides at ensuring all content is accessible to the hearing-impaired. I have attached several real-world subtitle files, electronically published by German-language broadcasters, under the provisions of the Doctrine of Fair Use (academic/research). The copyright for the attached files remains with the (internally visible) original publishers. (Regrettably, I only have access to German-language media. )