W3C home > Mailing lists > Public > public-texttracks@w3.org > September 2012

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

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Sat, 15 Sep 2012 09:25:12 +1000
Message-ID: <CAHp8n2kBDM7ZdHj-44vBatpJYKAZ1_aPv=+Cr0fAekLkFT6cTg@mail.gmail.com>
To: Jean-Baptiste Kempf <jb@videolan.org>
Cc: Philip Jägenstedt <philipj@opera.com>, public-texttracks <public-texttracks@w3.org>, David Singer <singer@apple.com>
On Thu, Sep 13, 2012 at 6:48 PM, Jean-Baptiste Kempf <jb@videolan.org> wrote:
> On Thu, Sep 13, 2012 at 09:00:08AM +0200, Philip Jägenstedt wrote :
>> I don't really see why we should try
>> to accommodate for non-Web users, in particular until they
>> themselves come to ask for it.
> And yet you took SRT, because it was very widely used by non-Web users,
> in order to have an important traction and facility to convert them into
> WebVTT.

>From our discussions at VDD [1] I took away that non-Web tools are
indeed keen for some header data in WebVTT, including kind
(chapters/captions/subtitles/descriptions/metadata), language (ISO
code), inline CSS styles (the limited allowed set for WebVTT),
possibly even label (a human readable string of what the content is).

I've even heard the request that we drop these attributes from the
<track> element and and just rely on this data being inside the WebVTT
file. This latter one we can't do IMO for several reasons:
* not all formats provide this information (and <track> was developed
to allow other formats, too - e.g. IE supports TTML).
* we don't want to have to download and parse a potentially large list
of file headers just to create a menu for the video element when the
user most likely will only need one or two of them.

Since we don't want to drop these attributes from <track> another
alternative for non-Web use would be to create a separate meta-data
file for a collection of WebVTT files and their video(s) that provides
the resource description. Something similar to what we experimented
with at Xiph with the ROE format [2].

Since this does not avoid the duplication of information and
introduced an extra complication by having to deal with yet another
file format, the discussion at VDD came to the conclusion that having
the information duplicated inside the WebVTT file header for non-Web
applications was the better solution.

JB, would you agree?


[1] http://www.videolan.org/videolan/events/vdd12/
[2] http://wiki.xiph.org/ROE
Received on Friday, 14 September 2012 23:26:02 UTC

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