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Re: Notify user agent available fragment

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Tue, 4 May 2010 11:22:23 +1000
Message-ID: <v2g2c0e02831005031822t9de15316i728fdf2cb75c1c56@mail.gmail.com>
To: Eric Carlson <eric.carlson@apple.com>
Cc: raphael.troncy@eurecom.fr, Jeroen Wijering <jeroen@longtailvideo.com>, public-media-fragment@w3.org
On Tue, May 4, 2010 at 1:46 AM, Eric Carlson <eric.carlson@apple.com> wrote:
>
> On May 3, 2010, at 6:00 AM, RaphaŽl Troncy wrote:
>
>>> How do you see the user-agent being notified in advance of the
>>> fragmentation possibilities of a certain resource?
>>
>> As Jack said, this is the problem of discovery, and as Davy rightly pointed out, if you are concerned of how a UA can know in advance which tracks (if any) are available in a media resource, then there are at least two ways:
>> †- use the Media Multitrack Javascript API developed by the accessibility task force of the HTML5 WG, http://www.w3.org/WAI/PF/HTML/wiki/Media_MultitrackAPI
>>
>
> †I don't think this will work as the UA will not be able to answer a priori questions about the composition of a media resource. The multitrack API will only work once the media element's readyState reaches HAVE_METADATA, which requires the UA to have loaded enough of the resource to know its duration, dimensions, etc. [1].
>
> [1] http://www.whatwg.org/specs/web-apps/current-work/multipage/video.html#dom-media-have_metadata


Incidentally, reaching the HAVE_METADATA state will also be a
precursor to some of the cases that the MF spec identifies, such as:
http://www.w3.org/2008/WebVideo/Fragments/WD-media-fragments-spec/#processing-protocol-UA-mapped
or http://www.w3.org/2008/WebVideo/Fragments/WD-media-fragments-spec/#processing-protocol-Server-mapped
. Thus it's not unreasonable to deal with this condition for certain
usage cases.

But I agree there needs to be a different means of discovery, too. The
ROE example of Davy deals with this situation well.

Regards,
Silvia.
Received on Tuesday, 4 May 2010 01:23:16 GMT

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