Re: Metadata in the VTT file header (bug 15851), use cases (and a need to close this)

On Thu, Aug 30, 2012 at 9:53 AM, Ian Hickson <ian@hixie.ch> wrote:
>> 2) Use in other embeddings.  MPEG has started work on specifying MP4
>> carriage of WebVTT in a track of the MP4 file. In this context, we need
>> some of the attributes that are carried in the HTML layer.  Some are
>> already covered or partially covered (e.g. all tracks can carry a
>> language in MP4) but not all.  WebM embedding is also under way.

Note: I had made a separate case for @kind in WebVTT:
https://www.w3.org/Bugs/Public/show_bug.cgi?id=18657

But that case can easily extend to @language and @label.

> This should be at the container level, not in VTT, IMHO. It is trivial for
> a container format to define how to include such information; even in the
> case of a format that can only embed data directly, the payload format can
> always be defined as being the data from the <track> element followed by
> the WebVTT data itself.

This is not about the container format. It is about the way in which
caption files get authored and distributed.

When the WebVTT file is authored, there is no <track> attribute to get
the information about @kind or @language out of, or to associate that
information with. The WebVTT file stands alone all by itself.

It may continue directly to the Web from here - in which case the Web
page author has to ask this additional information from the WebVTT
author.

It may also continue directly into a container format from here - in
which case the container encoding has to ask the additional
information from the WebVTT author.

Asking for that information out of band (i.e. outside the WebVTT file)
is an utter pain and prone to error when we already have a text file
that has space to carry this information.

Silvia.

Received on Thursday, 30 August 2012 02:14:36 UTC