- From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- Date: Tue, 29 Dec 2009 23:59:12 +1100
- To: Philip Jägenstedt <philipj@opera.com>
- Cc: Aryeh Gregor <Simetrical+w3c@gmail.com>, "Scheppe, Kai-Dietrich" <k.scheppe@telekom.de>, HTMLwg <public-html@w3.org>
On Tue, Dec 29, 2009 at 6:46 PM, Philip Jägenstedt <philipj@opera.com> wrote: > On Tue, 29 Dec 2009 04:17:56 +0100, Silvia Pfeiffer > <silviapfeiffer1@gmail.com> wrote: > >> On Tue, Dec 29, 2009 at 10:23 AM, Philip Jägenstedt <philipj@opera.com> >> wrote: >>> >>> On Mon, 28 Dec 2009 23:56:39 +0100, Aryeh Gregor >>> <Simetrical+w3c@gmail.com> >>> wrote: >>> >>>> On Mon, Dec 28, 2009 at 5:44 PM, Philip Jägenstedt <philipj@opera.com> >>>> wrote: >>>>> >>>>> The only wiggle-room this leaves for implementation is whether to show >>>>> the >>>>> poster frame or the first video frame when the first video frame has >>>>> been >>>>> decoded. I think it should be the poster image, if other browser >>>>> vendors >>>>> agree perhaps the spec should simply say that. >>>> >>>> That seems sensible to me as well. Why would implementations show the >>>> first video frame if a poster is explicitly provided? >>>> >>>>> If the author doesn't want to use a poster image they simply shouldn't >>>>> use >>>>> that attribute. To show a certain frame of video, set .currentTime in a >>>>> script. >>>> >>>> That's not equivalent. In particular, it will change what happens >>>> when the user hits play, and will probably change what gets buffered. >>>> Not to mention it requires script. >>>> >>>> Perhaps someone should suggest to the Media Fragments WG that they >>>> should create a syntax where you can address a frame of a video like a >>>> picture? The current WD doesn't seem to allow it: >>>> >>>> http://www.w3.org/2008/WebVideo/Fragments/WD-media-fragments-spec/ >>> >>> Shouldn't using e.g. #t=10,10 do just that? >> >> No, not if you are expecting it to return an actual image. A media >> fragment can only return the same mime type as the original resource. >> Thus, this will just return the video data for that particular time - >> it's still video data and not converted to jpg or png or anything >> else. It does essentially the same as setting the currentTime to 10. >> >> The media fragment WG recommends using queries where a image is to be >> extracted from a video, >> e.g. ?t=10,10&format=image/png . >> >> URI queries have been identified to be important for addressing media, >> in particular to extract shorter version of videos or retrieve another >> representation of a video (or audio). URI queries create new >> resources, so it is possible to do this with URI queries. URI >> fragments do not create new resources, so they cannot return a >> different mime type. >> >> The possibilities with URI queries are much larger and it is expected >> that media servers will develop a large repertoire of URI query >> parameters, but for now, the focus is on URI fragments and their >> equivalents in URI queries only where the mime type is not changed. >> >> Cheers, >> Silvia. >> > > In theory, the mime type does not need to change, all that matters is that a > single frame can be addressed, the rest is up to the UA. However, I doubt we > will see implementations supporting that very soon. OK, then the media fragment URL will do the job. As for implementations: it should be no more difficult than the network-based seeking approaches that are currently being used by browsers (in particular Firefox) to do the .currentTime offset. So, I am hopeful. Cheers, Silvia.
Received on Tuesday, 29 December 2009 13:00:05 UTC