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Re: AW: Public feedback on HTML5 video

From: Philip Jägenstedt <philipj@opera.com>
Date: Tue, 29 Dec 2009 08:46:52 +0100
To: "Silvia Pfeiffer" <silviapfeiffer1@gmail.com>
Cc: "Aryeh Gregor" <Simetrical+w3c@gmail.com>, "Scheppe, Kai-Dietrich" <k.scheppe@telekom.de>, HTMLwg <public-html@w3.org>
Message-ID: <op.u5ovweguatwj1d@sisko.linkoping.osa>
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.

-- 
Philip Jägenstedt
Core Developer
Opera Software
Received on Tuesday, 29 December 2009 07:47:38 UTC

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