- From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- Date: Tue, 4 May 2010 11:22:23 +1000
- 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, Raphaël 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 UTC