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

Re: metadata in the VTT file header, re-starting the conversation

From: Philip Jägenstedt <philipj@opera.com>
Date: Thu, 23 Feb 2012 10:29:07 +0100
To: "Silvia Pfeiffer" <silviapfeiffer1@gmail.com>
Cc: public-texttracks@w3.org
Message-ID: <op.v94kmtm8sr6mfa@kirk>
On Wed, 22 Feb 2012 22:13:55 +0100, Silvia Pfeiffer  
<silviapfeiffer1@gmail.com> wrote:

> On Thu, Feb 23, 2012 at 5:31 AM, Philip Jägenstedt <philipj@opera.com>  
> wrote:
>> On Wed, 22 Feb 2012 00:31:42 +0100, David Singer <singer@apple.com>  
>> wrote:
>>> Hi
>>> this conversation petered out, and we could really do with a way to  
>>> store
>>> attributes in the VTT file header:
>>> a) documented (standard)
>>> b) vendor-specific and experimental, probably
>>> Does anyone have any preferred syntax for doing this?  It's a little
>>> tricky, because one of the values I'd like to support is in-line CSS
>> In my private and humble opinion, a standardized format for metadata in
>> WebVTT overkill and not really something we need for v1. I'd prefer to
>> simply have some form of comment block that people can experiment with
>> before trying to go further.
> The need for this metadata is not with browsers, who can already get
> all the required information from the HTML <track> element. Desktop
> players are in an entirely different situation and lack that
> information. We need to provide a means to deliver that information to
> desktop players and indeed other desktop applications. Putting it
> outside of the WebVTT file is impractical. If we leave the format in
> which this data is given open for experimentation, we will get files
> in all sorts of formats that won't be able to be parsed by typical
> applications.

What information is it that desktop players need? Do any existing players  
do anything at all with metadata contained in any existing text tracks  
formats? The only really useful thing that I can think of is  
language-based font switching, and I've never seen a standalone player  
that does this.

> One such application is indeed the parsing of WebVTT
> files and encapsulation into media files such as WebM and MPEG. There
> is already a spec for parsing such metadata and putting it into WebM
> files right now. We don't want there to be a different and competing
> one for MPEG.
> In fact, this needs to be resolved soon so the WebM and MPEG
> encapsulation specs can go forward.

I'll have to read up on the WebM metadata thread soon, because I don't see  
why it would be dependent on the format WebVTT uses.

Philip Jägenstedt
Core Developer
Opera Software
Received on Thursday, 23 February 2012 09:29:36 UTC

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