Re: Embedding the track kind in WebVTT files

Please note that there are already bugs in the bug tracker for these:

Language: https://www.w3.org/Bugs/Public/show_bug.cgi?id=20853

Kind: https://www.w3.org/Bugs/Public/show_bug.cgi?id=18657 (read the
discussion here, please and re-open with new information)

All, including Style: https://www.w3.org/Bugs/Public/show_bug.cgi?id=15851

And from much earlier:
http://www.w3.org/WAI/PF/HTML/wiki/Media_WebVTT_Changes

We've also made a start at using such headers in:
https://dvcs.w3.org/hg/text-tracks/raw-file/default/608toVTT/608toVTT.html#metadata-xds

We have two options now:

1. We can continue to keep such metadata out of WebVTT and leave it to
authors to use what they see useful. Since the WebVTT spec allows for
such metadata by skipping over it, groups of useful metadata headers
can be specified by other bodies as needed.

2. We can pick a few important metadata headers and include them into
the WebVTT spec. This may be particularly useful for such headers that
are required for stand-alone use of WebVTT (Kind, Language, Label,
Style) and leave the rest to authors / metadata standardising bodies.


I still tend towards the second option.

Regards,
Silvia.




On Thu, Sep 12, 2013 at 7:30 PM, Cyril Concolato
<cyril.concolato@telecom-paristech.fr> wrote:
> Hi all,
>
> WebVTT files are/will be used in environments where there might not be an
> HTML page pointing to it. Some examples are:
> - WebVTT content embedded and multiplexed with video and audio in an MP4
> file
> - Plain text WebVTT files referenced by an adaptive streaming manifest (DASH
> MPD, HLS playlist, ...)
>
> All embedding environments typically enable marking a track with a language
> (e.g. an audio track) but not all can carry the kind types (subtitles,
> captions, metadata). In order to avoid losing that information in those
> environments, I think the WebVTT file should declare its kind. Also, when
> producing WebVTT files, it should be possible to indicate the language, kind
> or even label in the file itself, to avoid mistakes.
>
> I would like to propose to define standard WebVTT metadata headers, as
> follows:
> - WebVTT metadata header name: kind
> - WebVTT metadata header value: as defined by kind attribute of the track
> element in the HTML 5 specification
>
> - WebVTT metadata header name: language
> - WebVTT metadata header value: as defined by srclang attribute of the track
> element in the HTML 5 specification
>
> - WebVTT metadata header name: label
> - WebVTT metadata header value: as defined by label attribute of the track
> element in the HTML 5 specification
>
> Note that some people are already using non standard name/values for that
> (e.g.
> http://wiki.webmproject.org/webm-metadata/temporal-metadata/webvtt-metadata)
>
> Of course, this introduce redundancy when the embedding environment also
> sets those attributes and might be problematic if the values differ.
> Resolving conflicts should be specified by the embedding environment. In
> HTML, the information in the HTML page should probably have precedence, to
> be able to use a caption track as metadata, if the HTML author wants to.
>
> Comments ?
>
> Regards,
> Cyril
>
> --
> Cyril Concolato
> Maître de Conférences/Associate Professor
> Groupe Multimedia/Multimedia Group
> Telecom ParisTech
> 46 rue Barrault
> 75 013 Paris, France
> http://concolato.wp.mines-telecom.fr/
>
>

Received on Monday, 16 September 2013 07:22:30 UTC