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Re: timing model of the media resource in HTML5

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Wed, 3 Feb 2010 00:18:50 +1100
Message-ID: <2c0e02831002020518s469936dds510686c664f5e1e2@mail.gmail.com>
To: Philip Jägenstedt <philipj@opera.com>
Cc: Eric Carlson <eric.carlson@apple.com>, HTML Accessibility Task Force <public-html-a11y@w3.org>, Ken Harrenstien <klh@google.com>
On Tue, Feb 2, 2010 at 4:06 AM, Philip Jägenstedt <philipj@opera.com> wrote:
> On Mon, 01 Feb 2010 13:19:59 +0100, Silvia Pfeiffer
>> The argument that the markup may be wrong is a general argument
>> against any element on a HTML page. What if our image element links to
>> a non-existent image file? What if the javascript is broken? What if
>> the markup of the Web page is non-conformant? I think there are a
>> billion things in which a Web page can have errors in its markup and
>> still browsers try to render each and every one of them and even
>> tolerate some errors. They deal with failure. Why is that not possible
>> with video, too?
> I think this is quite similar to an unloaded <img>. For such an image you
> don't know the size and you won't find any (useful) properties in the
> context menu.
> As a side note, it seems that identifying tracks (uniquely, or at all) is
> actually unnecessary for the use case. You just need a list of available
> tracks that browsers can show in the context menu until HAVE_METADATA, at
> which point the actual tracks will be shown (hopefully be the same).

I think Ken might be happy with that. I'm not overly worried about
exposing identifiers in the markup (which may have been all the rage
here) - I was just trying to find a means to address the tracks
generally (eg. through media fragment URIs). But you are right, the
identifier doesn't have to be in the markup.

If we can expose the track composition as markup, it would make it
easier to integrate into a common menu with any externally referenced
subtitle / caption tracks.


>> How would you identify a track if you do not have a unique ID? what
>> would .enable() work on if not a track identifier?
>> video.firstTrack().enable() ? Even this implies that there is an order
>> and that we know what is in the track.
> Presumably the tracks could have language-information and names. But sure,
> id should also be exposed as track.id or similar. Still, the order of tracks
> would have to be well-defined or you'll get cross-browser incompatibilities
> in the blink of an eye.

I'm trying to address that with Ogg - there is no given order of
tracks right now, but we can easily define one - based on either the
order that their BOS pages appear in, or the order that the serial
number creates. Will share more when I know more.

Received on Tuesday, 2 February 2010 13:19:42 UTC

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