Re: [MSE] Resolving Bug 24370

On Sun, Apr 6, 2014 at 4:12 PM, Glenn Adams <> wrote:
> On Sat, Apr 5, 2014 at 11:55 PM, Silvia Pfeiffer <>
> wrote:
>> On Thu, Apr 3, 2014 at 12:20 AM, Jim Ley <> wrote:
>> > On 2 April 2014 09:26, Silvia Pfeiffer <>
>> > wrote:
>> >>
>> >> On Wed, Apr 2, 2014 at 6:04 PM, Jim Ley <> wrote:
>> >> >
>> >> > Isn't the use case for language being mutable simply live subtitles
>> >> > of a
>> >> > live "channel" that has programmes in different languages and
>> >> > therefore
>> >> > has
>> >> > closed captions / subtitles in different languages.
>> >>
>> >> Each one of those subtitle languages would be a different track, so
>> >> there is no need for mutability.
>> >
>> >
>> > No they're not, some shows are in English, some are in Welsh, the
>> > subtitle
>> > track is a single one for the live broadcast, similarly with audio, the
>> > broadcast audio changes languages.
>> Every show should have its own subtitle track.
> That is an operational policy issue that shouldn't be determined by the
> technology. For example, TTML explicitly supports the presence of multiple
> languages in a single TTML document. The user of TTML decides how to use it:
> whether to create different TTML files for different languages, or whether
> to merge different languages into the same TTML document (allowing selection
> to occur at processing or rendering time).

You can do that if you just deliver content and leave the rendering to
the application.

In the discussed case, the user of the technology is the browser user
and there are certain assumptions under which content is consumed.

I explained the poor consequences that a mid-change of track language
and kind can have on the example of a blind user. Do you disagree with
that example?

> It should not be construed to be poor practice of a TTML author merges
> different languages into the same file,

That may be as is.

> which translates to a single track
> using HTML5 mechanisms.

At the point where you hook into HTML5, you have to deal with the
content consumption approach of HTML5. A TTML file with cues of
multiple languages should be converted into as many tracks as there
are languages in use. This is a requirement of the way in which tracks
are consumed in a HTML5 browser. A TTML mapping into HTML5 would need
to provide for this functionality.


Received on Sunday, 6 April 2014 06:22:05 UTC